A friend and reader of my health reports is worried about contracting prostate cancer and asked what diet would be best to fight off prostate cancer. Here are the research reports I looked at in this regard:
Statins may slow prostate growth
Statins drugs prescribed to treat high cholesterol may also work to slow prostate growth in men who have elevated PSA levels, according to an analysis led by researchers at Duke University Medical Center.
The finding, presented at the annual meeting of the American Urological Association, provides additional insight into the effects of cholesterol-lowing drugs such as statins on the prostate. Previous studies at Duke and elsewhere had found a link between statins and lower levels of PSA, a protein produced by the prostate that is often elevated by cancer or by non-lethal prostatic diseases.
In the current finding, prostatic growth rate diminished among men with elevated PSA levels who took statins, although that effect was relatively small and tapered off after about two years.
"Given that prostate enlargement is an important health problem in the United States and elsewhere, and will be a larger problem as the population ages, it's important to understand and treat its causes," said Roberto Muller, M.D., a urology fellow at Duke and lead author of the study.
Enlarged prostate, most commonly diagnosed as benign prostate hyperplasia, causes urinary problems that can escalate to bladder and kidney damage. Up to 90 percent of men over the age of 70 have some symptoms associated with enlarged prostate, according to the National Institutes of Health.
Muller and colleagues used data gathered for an unrelated, large trial originally testing whether a drug called dutasteride could help reduce the risk of prostate cancer. To test their hypothesis that statins may be associated with slower prostate growth, the researchers culled the data of more than 6,000 men, including 1,032 who also took statins.
Men on statins tended to be older than non-users, and thus were expected to have greater prostate sizes. But prostate sizes were actually similar between statin users and non-users at the start of the study. That finding provided the first suggestion that statins might affect prostate growth.
When changes in prostate growth were compared two years after the start of the trial, men in the study who took a statin drug had less prostate growth, regardless of whether they had been randomly assigned to take dutasteride or a dummy pill. Prostate growth was an average 5 percent less in men who took both a statin and dutasteride pill compared to men who took only dutasteride. For those taking a statin and a dummy pill, prostate growth was 3.9 percent less than for men taking only the placebo.
Those reductions, however, did not persist after two years.
"We don't yet understand the mechanisms that might be causing this," Muller said. "Some have suggested that statins may have anti-inflammatory properties, and inflammation has been linked to prostate growth, but this needs further study."
Muller said the findings in the current research also suggest that lifestyle choices such diet and exercise may not only affect cholesterol, but also prostate health.
"Prostate enlargement was once considered an inexorable consequence of aging and genetics, but there is growing awareness that prostate growth can be influenced by modifiable risk factors," Muller said. "In this context, the role of blood cholesterol levels and cholesterol-lowering drugs such as statins warrants further study."
Oral Vitamin D Supplements Fight Prostate Cancer
Higher oral doses of plain vitamin D raised levels of calcitriol in prostate tissue. Higher prostate levels of calcitriol, a hormone made from vitamin D, corresponded with lower levels of the proliferation marker Ki67 and increased levels of cancer growth-inhibitory microRNAs in prostate cancer cells.
The results not only point to the mechanisms by which vitamin D affects the rate of prostate cancer growth, but also indicate that vitamin D may slow the growth of prostate cancer cells — a key finding given that the role of vitamin D in prostate cancer has been “controversial, with some suggesting that higher levels of vitamin D should be avoided,” said Reinhold Vieth, Ph.D., professor at the University of Toronto in Toronto, Ontario, Canada.
“This study shows calcitriol makes the foot come off the gas pedal of cancer growth. We are not able to prove that the speed of the car has slowed down, but it certainly is a good sign,” said Vieth. “We expect that this early-phase clinical trial will open the door for more detailed clinical research into the usefulness of vitamin D in the treatment or prevention of prostate cancer.”
Vieth and colleagues previously reported that in men who were being monitored regularly for prostate cancer, higher vitamin D levels slowed the rate of rise in prostate-specific antigen levels. They randomly assigned 66 men scheduled for radical prostatectomy to daily vitamin D in doses of 400, 10,000 or 40,000 IU for three to eight weeks before surgery. Researchers found that calcitriol levels in the prostate increased progressively with each daily dose of vitamin D, with 40,000 IU showing the highest levels. These higher levels of calcitriol corresponded with lower prostate levels of Ki67, a protein that indicates prostate cancer cell growth, as well as higher levels of specific growth-inhibitory microRNAs.
Vieth stressed that he and his colleagues do not advocate vitamin D supplementation in doses higher than 4,000 IU daily. Patients were assigned to the 40,000 IU daily dose because of the short presurgical time frame available for study, not as a regular regimen.
“Plain vitamin D provides the raw material to permit the body to take care of its own needs,” he said. “We showed here that plain vitamin D allows the prostate to regulate its own level of calcitriol, and at the doses we used, for the time frame we used, it has been safe with the hoped-for desirable outcomes.”
The next step in this line of research will be to conduct a phase III clinical trial in which men who are being monitored for prostate cancer progression will be randomly assigned to placebo or to a “high” dose of plain vitamin D.
Oregano Kills Prostate Cancer Cells
Oregano, the common pizza and pasta seasoning herb, has long been known to possess a variety of beneficial health effects, but a new study by researchers at Long Island University (LIU) indicates that an ingredient of this spice could potentially be used to treat prostate cancer, the second leading cause of cancer death in American men.
Prostate cancer is a type of cancer that starts in the prostate gland and usually occurs in older men. Recent data shows that about 1 in 36 men will die of prostate cancer. Estimated new cases and deaths from this disease condition in the US in 2012 alone are 241,740 and 28,170, respectively. Current treatment options for patients include surgery, radiation therapy, hormone therapy, chemotherapy, and immune therapy. Unfortunately, these are associated with considerable complications and/or severe side effects.
Dr. Supriya Bavadekar, PhD, RPh, Assistant Professor of Pharmacology at LIU's Arnold & Marie Schwartz College of Pharmacy and Health Sciences, is currently testing carvacrol, a constituent of oregano, on prostate cancer cells. The results of her study demonstrate that the compound induces apoptosis in these cells. Apoptosis, Dr. Bavadekar explains, is programmed cell death, or simply "cell suicide." Dr. Bavadekar and her group are presently trying to determine the signaling pathways that the compound employs to bring about cancer cell suicide.
"We know that oregano possesses anti-bacterial as well as anti-inflammatory properties, but its effects on cancer cells really elevate the spice to the level of a super-spice like turmeric," said Dr. Bavadekar. Though the study is at its preliminary stage, she believes that the initial data indicates a huge potential in terms of carvacrol's use as an anti-cancer agent. "A significant advantage is that oregano is commonly used in food and has a 'Generally Recognized As Safe' status in the US. We expect this to translate into a decreased risk of severe toxic effects."
"Some researchers have previously shown that eating pizza may cut down cancer risk. This effect has been mostly attributed to lycopene, a substance found in tomato sauce, but we now feel that even the oregano seasoning may play a role," stated Dr. Bavadekar. "If the study continues to yield positive results, this super-spice may represent a very promising therapy for patients with prostate cancer."
Green Tea Fights Prostate Cancer (White Tea w/ Citrus Should Be Even Better)
Six cups of green tea a day may slow the progression of prostate cancer, a new study suggests.
The finding stems from research that showed prostate patients scheduled for a type of surgery known as a prostatectomy, where the prostate is removed, reduced their levels of some disease-associated inflammation by drinking lots of brewed green tea in the weeks preceding the operation. And that reduction in inflammation may inhibit tumor growth, the researchers suggested.
Their results were to be presented Thursday at the American Association for Cancer Research's annual prevention conference in Anaheim, Calif.
The notion that the polyphenol compounds found in green tea might have a protective effect against prostate cancer has yet to be confirmed outside a laboratory setting. However, this latest report builds on previous Italian research that suggested that consuming green tea extract may help lower the risk that a precancerous condition will develop into full-blown prostate cancer.
And related research that was also presented at the cancer research conference suggested that the flavonoids found in fruits and vegetables may be associated with a lower risk of developing aggressive prostate cancer.
However, at least one urologist, Dr. Mark Soloway, chairman emeritus of urology at the University of Miami Miller School of Medicine, pointed to the new study's limitations, and said it was too soon to say that green tea had any impact on prostate cancer.
Scientific findings presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
In this latest green tea study, men who drank the beverage for three to eight weeks prior to surgery experienced a noticeable drop in both serum prostate-specific antigen (PSA) concentrations and PSA protein expression by the time they went under the knife. The fall-off in such telltale signs of disease was accompanied by reductions in both disease-linked inflammation and oxidative DNA damage, the study authors said.
"To see this effect, you would need to drink a lot of green tea," stressed study author Susanne Henning, a registered dietician and adjunct professor with the University of California, Los Angeles David Geffen School of Medicine. "Two cups a day is not going to help. In fact, we had our men drink six cups spread out all throughout the day, which I think was beneficial because green tea polyphenols are excreted very rapidly, so if you drink it that way you keep your levels up. And that seems to be the important factor in keeping the protection going."
To explore the anti-cancer potential of green tea, the authors focused on 67 prostate cancer patients, all of whom were weeks away from surgery. About half the men were randomly assigned to a six-cup-a-day regimen of green tea leading up to surgery, while the others consumed water instead.
The result: Blood and urine samples analyzed alongside tissue samples taken during surgery revealed that the green tea group fared significantly better on key signs of inflammation, PSA levels and expression and DNA damage.
However, no notable difference was found between the two groups in terms of tumor cell growth.
Henning stressed the need for more research on the potential green-tea/prostate cancer connection, and her team is currently planning new animal investigations involving combinations of green tea and other natural foods.
While this research showed an association between green tea and prostate cancer, it did not prove a cause-and-effect link.
"Actually, several food agents have been under investigation for their protective impact," she noted. "Lycopene and omega-3 fatty acids, for example. So, I would say that if you have cancer and you want to make a decision about all of this, then think of incorporating all of those as a part of a lifestyle change. I know that if I was diagnosed with prostate cancer, I would try to change my lifestyle. And that would mean, in addition to eating lots of fruits and vegetables and trying to lose weight and exercising, that I would definitely drink green tea."
The University of Miami's Soloway said that while drinking green tea probably does not have a downside, this "limited study" does not confirm its impact as a prostate cancer intervention.
"[There's] not much solid data to prove it," he said. "This is a small study, and it would take a longer study with hundreds of patients to 'prove' its benefit."
Soloway also noted that the jury is still out on whether inflammation even plays a significant role in cancer development. "It is very much a question," he said. "Not proven at all."
But, he agreed that until larger studies come along to explore green tea's potential, "it might be worth giving it a shot."
Antioxidants in Tea, Fruit, Veggies Might Fight Prostate Cancer
Prostate cancer patients who, before their diagnosis, routinely consumed hefty helpings of the flavonoid compounds found in plant-based foods and drinks may be at lower risk for the most aggressive form of the disease, new research suggests.
But the research has significant limitations, the study authors noted, so it's too soon to say that a plant-based diet protects against prostate cancer.
Flavonoids are found in vegetables and fruits, as well as in tea, wine, juices and cocoa. Researchers have long theorized that these particular antioxidants may help reduce cancer risk by fighting inflammation, oxidation, cell death and tumor cell growth.
The new study did not assess the ability of flavonoids to prevent the onset of cancer as a whole. But the investigation, involving about 1,900 patients newly diagnosed with prostate cancer, found that those whose diets included the highest amount of flavonoids were 25 percent less likely to have been diagnosed with the fastest-moving and harshest form of the disease compared to those who had been taking in the fewest flavonoids.
"We compared men with low-aggressive disease to high aggressive," said study lead author Susan Steck, associate professor at the University of South Carolina's Arnold School of Public Health. "We did not have a healthy comparison group. So while we think that consuming more fruits and vegetables will improve the odds of not getting prostate cancer altogether, we can't say that based on our study results."
"But what we are seeing here is the impact of flavonoids on reducing the risk for aggressive prostate cancer," she added. "They may not affect your risk for getting the cancer, but it may mitigate against the kind of cancer you would get."
Steck and her colleagues are scheduled to discuss their findings Wednesday at the annual cancer prevention meeting of the American Association for Cancer Research, in Anaheim, Calif.
The authors looked at self-reported dietary habits already in place at the time of diagnosis among their patient pool, which included 920 black men and 977 white men. No dietary intervention was imposed after diagnosis.
All the men had been enrolled in the North Carolina-Louisiana Prostate Cancer Project.
The new study found that smokers and men younger than 65 appeared to receive the most protective benefit from fruit and vegetable consumption.
The authors identified green and black tea, as well as orange and grapefruit juice, as the prime sources of flavonoids consumed by study participants. Strawberries, onions, cooked greens, kale and broccoli also were popular flavonoid-rich foods.
No single class of plant-based food was linked on its own to the observed protective effect, leading the team to conclude that the benefit was rooted in a dietary mix of flavonoids.
Dr. Lionel Banez, assistant professor of urologic surgery at Duke University Medical Center in Durham, N.C., said the study design makes it hard to read much into the findings.
It is "difficult to be confident about the conclusions," he said, given that the current study was a backward look at patients' recollections of their pre-diagnosis diets.
Banez suggested that the findings of a flavonoid benefit would be more reliable if they had stemmed from a highly controlled study of risk levels among patients who were proactively placed on a specific dietary plan, and then tracked for the future onset of cancer.
"These results are not enough to warrant recommending plant-based diets as regimens to treat prostate cancer or prevent aggressive prostate cancer," he said.
Although the study found an association between flavonoids and risk for a form of prostate cancer, it did not prove a cause-and-effect relationship. Because the study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
Daily Aspirin May Help Fight Prostate Cancer
Liauw and his team explored the potential benefit of aspirin use among nearly 6,000 men diagnosed with, and undergoing treatment for, prostate cancer.
The men were drawn from 41 different health centers across the United States, and all had undergone either surgery (radical prostatectomy) or radiotherapy.
The team noted that 37 percent of the patients were already taking some type of anticoagulant (aspirin, warfarin (Coumadin), clopidogrel (Plavix), and/or enoxaparin). No aspirin or other anticoagulant was prescribed once the study began.
After more than 10 years of follow-up, the team found that among those taking some type of anticoagulant, the risk of dying from prostate cancer was significantly lower than it was among those not taking one.
Further analysis revealed that most of the benefit came from aspirin use, which Liauw said was responsible for a 57 percent reduction in the risk of prostate cancer death.
Because dosage information was not collected, no conclusions could be drawn about exactly how much aspirin was most beneficial. However, the team noted that the protective effect was strongest among patients with particularly "high-risk" disease.
Both study teams said that more research is needed to confirm their respective findings. And neither study proved a cause-and-effect relationship between aspirin use and its effect on cancer.
"So, at this point, this is just hypothesis-generating," Liauw said. "It may be true, but it needs to be tested more formally."
Zhang added that although aspirin showed little benefit with respect to breast cancer risk, he doesn't see any cancer-related downside to their long-term use. However, for women seeking to reduce their breast cancer risk, "the best strategies remain to maintain an ideal weight, exercise, avoid long-term use of postmenopausal hormones, and minimize alcohol intake," he noted.
Two experts who wrote an accompanying editorial in the journal suggested that aspirin might make a difference among very specific subgroups of people.
"When looking at aspirin's impact on breast cancer risk, looking at all-comers and including all sorts of people who take anti-inflammatory drugs for all sorts of reasons might miss the kernel," said editorial lead author Dr. Clifford Hudis, chief of the breast cancer medicine service at Memorial Sloan-Kettering Cancer Center, in New York City. "That is to say that there may very well be a subset of people for whom taking aspirin can be of protective benefit "
"But," he added, "the answer always is and remains that you should talk to your doctor about this before deciding to take or not take anything, including aspirin, because none of these studies prove anything definitively one way or another."
Editorial co-author Dr. Andrew Dannenberg, director of the Weill Cornell Cancer Center, agreed.
"It continues to seem to me that aspirin does have a use for reducing the risk for certain cancers," he said. "However, aspirin also has side effects -- peptic ulcer disease and hemorrhagic stroke, which are real diseases. And therefore I'm still reluctant at this time to make specific recommendations that people take aspirin for the prevention for cancer. And I believe that prospective trials that better define dose and duration are required before anyone should make definitive recommendations for the use of aspirin in this context."
Prostate Cancer: Curcumin Curbs Metastases, Study Shows
Powdered turmeric has been used for centuries to treat osteoarthritis and other illnesses. Its active ingredient, curcumin, inhibits inflammatory reactions. A new study led by a research team at Ludwig-Maximilians-Universität (LMU) in Munich now shows that it can also inhibit formation of metastases.
Prostate cancer is one of the most prevalent malignancies in the Western world, and is often diagnosed only after metastatic tumors have formed in other organs. In three percent of cases, these metastases are lethal. A research team led by PD Dr. Beatrice Bachmeier at LMU Munich has been studying the mode of action of a natural product that inhibits the formation of metastases. The compound is found in turmeric, a plant that has been used for medicinal purposes for thousands of years, and is a major ingredient of curry.
Bachmeier's research centers on curcumin, the polyphenol responsible for the characteristic color of curry. Curcumin is well tolerated and is therefore, in principle, suitable both for prophylactic use (primary prevention) and also for the suppression of metastases in cases where an established tumor is already present (secondary prevention). In a previous study Bachmeier and her colleagues had demonstrated that the substance reduces statistically significantly the formation of lung metastases in an animal model of advanced breast cancer.
Mitigating metastasis The new study was designed to investigate the efficacy of curcumin in the prevention of prostate cancer metastases, and to determine the agent's mechanism of action. The researchers first examined the molecular processes that are abnormally regulated in prostate carcinoma cells. Breast and prostate cancers are often associated with latent or chronic inflammatory reactions, and in both cases, the tumor cells were found to produce pro-inflammatory immunomodulators including the cytokines CXCL1 und CXCL2.
The researchers went on to show that curcumin specifically decreases the expression of these two proteins, and in a mouse model, this effect correlated with a decline in the incidence of metastases. "Due to the action of curcumin, the tumor cells synthesize smaller amounts of cytokines that promote metastasis," says Bachmeier. "As a consequence, the frequency of metastasis formation in the lungs is significantly reduced, in animals with breast cancer, as we showed previously, or carcinoma of the prostate, as demonstrated in our new study."
Bachmeier therefore believes that curcumin may be useful in the prevention of breast and prostate cancers -- which are both linked to inflammation -- and in reducing their metastatic potential. "This does not mean that the compound should be seen as a replacement for conventional therapies. However, it could play a positive role in primary prevention -- before a full-blown tumor arises -- or help to avert formation of metastases. In this context the fact that the substance is well tolerated is very important, because one can safely recommend it to individuals who have an increased tumor risk."
A daily intake of up to 8g of curcumin is regarded as safe, and its anti-inflammatory properties have long been exploited in traditional oriental medicine. Men with benign hyperplasia of the prostate (BHP) are one possible target group for prophylaxis, as are women who have a family history of breast cancer. The agent might also be valuable as a supplement to certain cancer therapies. At all events, curcumin's beneficial effects must first be confirmed in controlled clinical tests. Bachmeier is now planning such a trial in patients who suffer from therapy-resistant carcinoma of the prostate.
Curry Spice Component May Help Slow Prostate Tumor Growth
Curcumin, an active component of the Indian curry spice turmeric, may help slow down tumor growth in castration-resistant prostate cancer patients on androgen deprivation therapy (ADT), a study from researchers at Jefferson's Kimmel Cancer Center suggests.
Reporting in a recent issue of Cancer Research, Karen Knudsen, Ph.D., a Professor of Cancer Biology, Urology and Radiation Oncology at Thomas Jefferson University, and colleagues observed in a pre-clinical study that curcumin suppresses two known nuclear receptor activators, p300 and CPB (or CREB1-binding protein), which have been shown to work against ADT.
ADT aims to inhibit the androgen receptor -- an important male hormone in the development and progression of prostate cancer -- in patients. But a major mechanism of therapeutic failure and progression to advanced disease is inappropriate reactivation of this receptor. Sophisticated tumor cells, with the help of p300 and CPB, sometimes bypass the therapy.
Thus, development of novel targets that act in concert with the therapy would be of benefit to patients with castration-resistant prostate cancer.
For the study, prostate cancer cells were subjected to hormone deprivation in the presence and absence of curcumin with "physiologically attainable' doses. (Previous studies, which found similar results, included doses that were not realistic.)
Curcumin augments the results of ADT, and reduced cell number compared to ADT alone, the researchers found. Moreover, the spice was found to be a potent inhibitor of both cell cycle and survival in prostate cancer cells.
To help support their findings, the researchers also investigated curcumin in mice, which were castrated to mimic ADT. They were randomized into two cohorts: curcumin and control. Tumor growth and mass were significantly reduced in the mice with curcumin, the researchers report.
These data demonstrate for the first time that curcumin not only hampers the transition of ADT-sensitive disease to castration-resistance, but is also effective in blocking the growth of established castrate-resistant prostate tumors.
"This study sets the stage for further development of curcumin as a novel agent to target androgen receptor signaling," said Dr. Knudsen. "It also has implications beyond prostate cancer since p300 and CBP are important in other malignancies, like breast cancer. In tumors where these play an important function, curcumin may prove to be a promising therapeutic agent."
Omega-3s May Help Slow Prostate Cancer Growth
Research in mice suggests that a diet high in omega-3 fatty acids found in fish oil and certain types of fish could potentially improve the prognosis of men who are genetically prone to develop prostate cancer.
“This study clearly shows that diet can tip the balance toward a good or a bad outcome,” said senior researcher Yong Q. Chen, Ph.D., from Wake Forest University School of Medicine. “It’s possible that a change in diet could mean the difference between dying from the disease and surviving with it.”
In mice that were engineered with a genetic defect that caused prostate cancer, a diet high in omega-3 fatty acids beginning at birth reduced tumor growth, slowed disease progression and increased survival.
Prostate cancer is the most frequently diagnosed cancer and is a leading cause of death in men in the United States. Population studies have suggested that consumption of fish or fish oil reduces prostate cancer incidence. However, these investigations have been hampered by the difficulty people have in accurately reporting their dietary intake.
The goal of the current study was to explore gene-diet interactions in prostate cancer. It involved mice that were engineered with a genetic defect – they lacked a tumor suppressor gene and spontaneously developed prostate cancer. This gene (Pten) is absent in 60 to 70 percent of metastatic cancers in humans.
The engineered mice and “wild-type” (or non-engineered) mice were fed varying levels of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs). Both are “essential” fatty acids, which means the body needs them for proper cell function but cannot produce them. Many vegetable oils contain omega-6 PUFA. Fish like mackerel, lake trout, herring, sardines, albacore tuna and salmon are high in omega-3 fatty acids.
Nutritionists recommend that people consume equal proportions of omega-3 and omega-6 PUFA. However, in current western diets, the proportion of omega-6 to omega-3 is between 30 and 50 to one.
The mice were fed either a diet high in omega-3 (ratio of omega-6 to omega-3 was 1:1) a diet low in omega 3 (ratio omega-6 to omega-3 was 20:1), or a diet high in omega-6 (ratio of omega-6 to omega-3 was 40:1). The scientists compared survival rates and weighed the animals’ prostates to measure tumor progression.
Mice with the tumor suppressor gene remained free of tumors and had 100 percent survival, regardless of diet. In mice with the gene defect, survival was 60 percent in animals on the high omega-3 diet, 10 percent in those on the low omega-3 diet and 0 percent in those on the high omega-6 diet.
“This suggests that if you have good genes, it may not matter too much what you eat,” said Chen, a professor of cancer biology. “But if you have a gene that makes you susceptible to prostate cancer, your diet can tip the balance. Our data demonstrate the importance of gene-diet interactions, and that genetic cancer risk can be modified favorable by omega-3 PUFA.”
Chen said dietary changes may be particularly beneficial in people prone to prostate cancer because the disease is usually diagnosed in older men and the tumors are slow-growing. It’s possible that eating a high omega-3 diet could delay tumor development or progression long enough for the man to live out his natural lifespan with prostate cancer.
“Our data imply a beneficial effect of omega-3 PUFA on delaying the onset of human prostate cancer,” Chen said.
He noted that the mice got lifetime exposure of omega-3 and that some people may not be willing to change their diets until they develop cancer. He hopes to study whether there would be beneficial effects of adding omega-3 PUFA to the diet after tumors have developed.
He cautioned that the effects were obtained with the omega-3s found in fish oil and that omega-3s from flaxseed oil and other plants may not provide the same results.
Flaxseed stunts the growth of prostate tumors
Flaxseed, an edible seed that is rich in omega 3-fatty acids and fiber-related compounds known as lignans, is effective in halting prostate tumor growth, according to a study led by Duke University Medical Center researchers. The seed, which is similar to a sesame seed, may be able to interrupt the chain of events that leads cells to divide irregularly and become cancerous.
"Our previous studies in animals and in humans had shown a correlation between flaxseed supplementation and slowed tumor growth, but the participants in those studies had taken flaxseed in conjunction with a low-fat diet," said Wendy Demark-Wahnefried, Ph.D., a researcher in Duke's School of Nursing and lead investigator on the study. "For this study, we demonstrated that it is flaxseed that primarily offers the protective benefit."
In the study, the researchers examined the effects of flaxseed supplementation on men who were scheduled to undergo prostatectomy -- surgery for the treatment of prostate cancer. The men took 30 grams of flaxseed daily for an average of 30 days prior to surgery. Once the men's tumors were removed, the researchers looked at tumor cells under a microscope, and were able to determine how quickly the cancer cells had multiplied.
Men taking flaxseed, either alone or in conjunction with a low-fat diet, were compared to men assigned to just a low-fat diet, as well as to men in a control group, who did not alter or supplement their daily diet. Men in both of the flaxseed groups had the slowest rate of tumor growth, Demark-Wahnefried said. Each group was made up of about 40 participants.
Study participants took the flaxseed in a ground form because flaxseed in its whole form has an undigestible seed coat, she said. Participants elected to mix it in drinks or sprinkle it on food, such as yogurt.
"The results showed that the men who took just flaxseed as well as those who took flaxseed combined with a low-fat diet did the best, indicating that it is the flaxseed which is making the difference," Demark-Wahnefried said.
Flaxseed is thought to play a part in halting the cellular activity that leads to cancer growth and spread. One reason could be that as a source of omega-3 fatty acids, flaxseed can alter how cancer cells lump together or cling to other body cells, both factors in how fast cancer cells proliferate, Demark-Wahnefried said. The researchers also suspect that lignans may have antiangiogenic properties, meaning they are able to choke off a tumor's blood supply, stunting its growth.
"We are excited that this study showed that flaxseed is safe and associated with a protective effect on prostate cancer," Demark-Wahnefried said.
The researchers hope to next test the effectiveness of flaxseed supplementation in patients with recurrent prostate cancer, and ultimately to study its role as a preventive agent.
High-fiber foods show promise against prostate cancer
A dietary component found in most whole grain foods, beans, nuts and other high-fiber items shows promise in animal studies as a potent weapon for preventing prostate cancer. The compound, inositol hexaphosphate (IP6), was fed to animal models of prostate cancer and resulted in up to a 66 percent reduction in tumor size in comparison to control animals that were given water instead, the researchers say. The compound, which is sold in stores as a dietary supplement, adds to a growing number of products — including lycopene, milk thistle extract, vitamin E and selenium — that also have shown promise against prostate cancer, says Rajesh Agarwal, Ph.D., a professor in the Department of Pharmaceutical Sciences at the University of Colorado Health Sciences Center in Denver.
Soy found protective against localized prostate cancer
The largest study examining the relationship between the traditional soy-rich Japanese diet and development of prostate cancer in Japanese men has come to a seemingly contradictory conclusion: intake of isoflavone chemicals, derived largely from soy foods, decreased the risk of localized prostate cancer but increased the risk of advanced prostate cancer.
The prospective study of 43,509 men, published in the March issue of Cancer Epidemiology, Biomarkers & Prevention, suggests that the effects of isoflavones on prostate cancer development may differ according to disease stage, say researchers at the National Cancer Center in Japan.
One possible explanation is that isoflavones may delay the progression of latent prostate cancer only; once tumors lose estrogen-receptor beta expression and become aggressive, isoflavones may fail to protect against the development of advanced cancer, and might even increase the risk of progression, possibly by reducing serum testosterone, researchers say. It is also possible that advanced and localized prostate cancer may be different tumor subtypes, which may react differently to isoflavones.
"The present findings provide no clear understanding of when or how localized cancer will develop to aggressive cancer, and of the related effect of isoflavones," said the study's first author, Norie Kurahashi, M.D., of the Epidemiology and Prevention Division of the National Cancer Center.
"Given that Japanese consume isoflavones regularly throughout life, we do not know the period during which the effects of isoflavones on prostate cancer are preventive, and further research is required to find that out, including well-designed clinical trials," she said.
Until those studies are done, the researchers recommend that Japanese men continue to consume isoflavones through their food and not through supplements.
"Consumption of isoflavones from traditional Japanese food throughout life may protect against the incidence of prostate cancer, but we cannot recommend the use of isoflavones from supplements for people who do not regularly consume these chemicals, because the relationship between isoflavones and the risk of advanced prostate cancer is not yet clear," Kurahashi said.
Isoflavones act as both strong antioxidants and plant-based estrogens. Soybeans are the most common source of isoflavones, especially genistein and daidzein, which have been shown in some animal studies to exert a protective effect against prostate cancer.
Japanese men eat significantly more soy-based foods than do Western men, and the incidence of prostate cancer is much lower in Asian countries than in Western countries. Still, reviews of latent, or clinically insignificant, prostate cancer findings in autopsy reports have revealed no difference between the populations so scientists have theorized that isoflavones stop latent cancers from developing further.
But because smaller epidemiological studies in Japan have reached differing conclusions about the protective effects of soy on prostate cancer development, this research team conducted the most comprehensive analysis to date. They polled thousands of men age 40-69 about their consumption of 147 foods, the most popular of which were miso soup (primarily made from fermented soybeans), natto (also a product of fermented soybeans) and tofu, made from soy milk. Japanese consume miso soup more frequently, usually daily, than other soy foods, and miso, natto, and tofu account for about 90 percent of the population's consumption of daidzein and genistein, according to Kurahashi.
The researchers then followed participants from 1995 through 2004 and found that 307 men were diagnosed with prostate cancer. In this group, 74 cases were advanced, 218 were confined to the prostate organ, and 15 were of undetermined stage.
They concluded that intake of genistein, daidzein, miso soup and soy food had no overall link to diagnosis of prostate cancer. However, they calculated that the risk of developing localized prostate cancer was 50 percent lower in men who ate the most isoflavones compared to men who ate the least _ meaning that men in the top category ate between two and three times as much isoflavone-rich food.
However, in a discovery they cannot explain, they also calculated that the risk of developing advanced prostate cancer was twice as high in men who consumed two or more bowls of miso soup a day than in men who ate less than one bowl of soup.
They also found that the protective effect of isoflavone-rich food was strongest in men who were older than 60: the more isoflavones they ate, the more they reduced their risk of developing localized prostate cancer. "Isoflavone may be protective for localized prostate cancer only in men aged more than 60 years, and may not have a protective effect in the early stage of prostate cancer in younger men," the researchers conclude in their study.
The inconsistencies in the finding- that isoflavones decreased the risk of localized prostate cancer, but not the risk of advanced prostate cancer _ could be errors in food measurement, or could be due to the fact that the number of participants who developed advanced prostate cancer was small, said Kurahashi. Or, as researchers speculate, isoflavones could interact with the estrogen receptor on prostate tissue enough to inhibit production of testosterone, which can fuel prostate cancer. When tumors lose all of their estrogen receptors and stop responding to isoflavone-induced hormonal interference, they grow aggressively.
"A broad body of research is required to clarify the timing and period of isoflavones' preventive effect on prostate cancer development," Kurahashi said.
Worried about prostate cancer? Tomato-broccoli combo shown to be effective
A new University of Illinois study shows that tomatoes and broccoli--two vegetables known for their cancer-fighting qualities--are better at shrinking prostate tumors when both are part of the daily diet than when they're eaten alone.
"When tomatoes and broccoli are eaten together, we see an additive effect. We think it's because different bioactive compounds in each food work on different anti-cancer pathways," said University of Illinois food science and human nutrition professor John Erdman.
In a study published in the January 15 issue of Cancer Research, Erdman and doctoral candidate Kirstie Canene-Adams fed a diet containing 10 percent tomato powder and 10 percent broccoli powder to laboratory rats that had been implanted with prostate cancer cells. The powders were made from whole foods so the effects of eating the entire vegetable could be compared with consuming individual parts of them as a nutritional supplement.
Other rats in the study received either tomato or broccoli powder alone; or a supplemental dose of lycopene, the red pigment in tomatoes thought to be the effective cancer-preventive agent in tomatoes; or finasteride, a drug prescribed for men with enlarged prostates. Another group of rats was castrated.
After 22 weeks, the tumors were weighed. The tomato/broccoli combo outperformed all other diets in shrinking prostate tumors. Biopsies of tumors were evaluated at The Ohio State University, confirming that tumor cells in the tomato/broccoli-fed rats were not proliferating as rapidly. The only treatment that approached the tomato/broccoli diet's level of effectiveness was castration, said Erdman.
Aspirin may help prevent prostate cancer
Common painkillers like aspirin and ibuprofen appear to lower a man's PSA level, the blood biomarker widely used by physicians to help gauge whether a man is at risk of prostate cancer.
But the authors of the study caution that men shouldn't take the painkillers in an effort to prevent prostate cancer just yet.
"We showed that men who regularly took certain medications like aspirin and other non-steroidal anti-inflammatory drugs, or NSAIDS, had a lower serum PSA level," said first author Eric A. Singer, M.D., M.A., a urology resident at the University of Rochester Medical Center. "But there's not enough data to say that men who took the medications were less likely to get prostate cancer. This was a limited study, and we do not know how many of those men actually got prostate cancer."
Singer's team studied the records of 1319 men over the age of 40 who took part in the 2001-2002 National Health and Nutrition Examination Survey (NHANES), a health census conducted by the Centers for Disease Control and Prevention. The team looked at the men's use of NSAIDs such as aspirin and ibuprofen, as well as the painkiller acetaminophen, and at their PSA levels. A man's level of PSA, or prostate-specific antigen, is one of many clues that physicians watch to gauge a man's risk of getting prostate cancer.
The team found that men who used NSAIDs regularly had PSA levels about 10 percent lower compared to men who did not. The team made a similar observation with acetaminophen, but the result was not statistically significant due to the lower number of men in the study taking the medication.
While it might be easy to assume that a lowered PSA level automatically translates to a lowered risk of prostate cancer, the authors stress that it's too soon to draw that conclusion.
"While our results are consistent with other research that indicates that certain painkillers may reduce a man's risk of getting prostate cancer, the new findings are preliminary and don't prove a link," said corresponding author Edwin van Wijngaarden, Ph.D., assistant professor in the Department of Community and Preventive Medicine.
Singer said that a man's PSA level can be elevated for reasons unrelated to cancer. Sometimes, for instance, while inflammation is part of a cancer process, sometimes it is not, and so it's possible that a lowered PSA reflects reduced inflammation without affecting a man's risk of prostate cancer. Another possibility is that a PSA level lowered by NSAIDs might artificially mask a man's risk of getting prostate cancer: The medications might lower the PSA, but a man's risk might stay precisely the same.
"These findings underscore the importance for doctors to know what medications their patients are on," said Singer, who is chief Urology resident at the University of Rochester Medical Center. "For instance, there are medications commonly used to treat an enlarged prostate that can result in a decreased PSA, and most physicians know that. Doctors should also be asking about patients' use of NSAIDs such as aspirin and ibuprofen.
"The data is very interesting, but it will take more research to determine how to interpret the findings. In the meantime, this shouldn't change men's behavior or prompt them to take these medications to try to prevent prostate cancer."
"As nutritionists, it was very exciting to compare this drastic surgery to diet and see that tumor reduction was similar. Older men with slow-growing prostate cancer who have chosen watchful waiting over chemotherapy and radiation should seriously consider altering their diets to include more tomatoes and broccoli," said Canene-Adams.
How much tomato and broccoli should a 55-year-old man concerned about prostate health eat in order to receive these benefits? The scientists did some conversions.
"To get these effects, men should consume daily 1.4 cups of raw broccoli and 2.5 cups of fresh tomato, or 1 cup of tomato sauce, or _ cup of tomato paste. I think it's very doable for a man to eat a cup and a half of broccoli per day or put broccoli on a pizza with _ cup of tomato paste," said Canene-Adams.
Erdman said the study showed that eating whole foods is better than consuming their components. "It's better to eat tomatoes than to take a lycopene supplement," he said. "And cooked tomatoes may be better than raw tomatoes. Chopping and heating make the cancer-fighting constituents of tomatoes and broccoli more bioavailable."
"When tomatoes are cooked, for example, the water is removed and the healthful parts become more concentrated. That doesn't mean you should stay away from fresh produce. The lesson here, I think, is to eat a variety of fruits and vegetables prepared in a variety of ways," Canene-Adams added.
Another recent Erdman study shows that rats fed the tomato carotenoids phytofluene, lycopene, or a diet containing 10 percent tomato powder for four days had significantly reduced testosterone levels. "Most prostate cancer is hormone-sensitive, and reducing testosterone levels may be another way that eating tomatoes reduces prostate cancer growth," Erdman said.
Erdman said the tomato/broccoli study was a natural to be carried out at Illinois because of the pioneering work his colleague Elizabeth Jeffery has done on the cancer-fighting agents found in broccoli and other cruciferous vegetables. Jeffery has discovered sulfur compounds in broccoli that enhance certain enzymes in the human body, which then act to degrade carcinogens.
"For ten years, I've been learning how the phytochemicals in tomatoes affect the progression of prostate cancer. Meanwhile Dr. Jeffery has been investigating the ways in which the healthful effects of broccoli are produced. Teaming up to see how these vegetables worked together just made sense and certainly contributes to our knowledge about dietary treatments for prostate cancer," said Erdman.
Coffee Consumption Associated with Reduced Risk of Advanced Prostate Cancer
While it is too early for physicians to start advising their male patients to take up the habit of regular coffee drinking, data presented at the American Association for Cancer Research Frontiers in Cancer Prevention Research Conference revealed a strong inverse association between coffee consumption and the risk of lethal and advanced prostate cancers.
“Coffee has effects on insulin and glucose metabolism as well as sex hormone levels, all of which play a role in prostate cancer. It was plausible that there may be an association between coffee and prostate cancer,” said Kathryn M. Wilson, Ph.D., a postdoctoral fellow at the Channing Laboratory, Harvard Medical School and the Harvard School of Public Health.
In a prospective investigation, Wilson and colleagues found that men who drank the most coffee had a 60 percent lower risk of aggressive prostate cancer than men who did not drink any coffee. This is the first study of its kind to look at both overall risk of prostate cancer and risk of localized, advanced and lethal disease.
“Few studies have looked prospectively at this association, and none have looked at coffee and specific prostate cancer outcomes,” said Wilson. “We specifically looked at different types of prostate cancer, such as advanced vs. localized cancers or high-grade vs. low-grade cancers.”
Caffeine is actually not the key factor in this association, according to Wilson. The researchers are unsure which components of the beverage are most important, as coffee contains many biologically active compounds like antioxidants and minerals.
Using the Health Professionals’ Follow-Up Study, the researchers documented the regular and decaffeinated coffee intake of nearly 50,000 men every four years from 1986 to 2006; 4,975 of these men developed prostate cancer over that time. They also examined the cross-sectional association between coffee consumption and levels of circulating hormones in blood samples collected from a subset of men in the cohort.
“Very few lifestyle factors have been consistently associated with prostate cancer risk, especially with risk of aggressive disease, so it would be very exciting if this association is confirmed in other studies,” said Wilson. “Our results do suggest there is no reason to stop drinking coffee out of any concern about prostate cancer.”
This association might also help understand the biology of prostate cancer and possible chemoprevention measures.
Walnuts good for the heart & prostate
Walnut consumption slows the growth of prostate cancer in mice and has beneficial effects on multiple genes related to the control of tumor growth and metabolism, UC Davis and the U.S. Department of Agriculture Western Regional Research Center in Albany, Calif. have found.
The study, by Paul Davis, nutritionist in the Department of Nutrition and a researcher with the UC Davis Cancer Center, announced the findings today at the annual national meeting of the American Chemical Society in San Francisco.
Davis said the research findings provide additional evidence that walnuts, although high in fat, are healthful.
"This study shows that when mice with prostate tumors consume an amount of walnuts that could easily be eaten by a man, tumor growth is controlled," he said. "This leaves me very hopeful that it could be beneficial in patients."
Prostate cancer affects one in six American men. It is one in which environmental factors, especially diet, play an important role. Numerous clinical studies have demonstrated that eating walnuts -- rich in omega-3 polyunsaturated fats, antioxidants and other plant chemicals -- decreases the risk of cardiovascular disease. These findings prompted the U.S. Food & Drug Administration in 2004 to approve, for the first time, a qualified health claim for reducing heart disease risk for a whole food.
Davis fed a diet with whole walnuts to mice that had been genetically programmed to get prostate cancer. After 18 weeks, they found that consuming the human equivalent of 2.4 ounces of walnuts per day resulted in significantly smaller, slower-growing prostate tumors compared to mice consuming the same diet with an equal amount of fat, but not from walnuts. They also found that not only was prostate cancer growth reduced by 30 to 40 percent, but that the mice had lower blood levels of a particular protein, insulin-like growth factor (IGF-1), which has been strongly associated with prostate cancer. Additionally, Davis and his research colleagues looked at the effect of walnuts on gene activity in the prostate tumors using whole mouse gene chip technology, and found beneficial effects on multiple genes related to controlling tumor growth and metabolism.
"This is another exciting study from UC Davis nutrition researchers, where truly promising results that have a molecular footprint are having beneficial effects against cancer," said Ralph deVere White, UC Davis Cancer Center director and a prostate cancer researcher. "We have to find a way to get these kinds of studies on nutritional products funded so that we can truly evaluate their effects on cancer patients."
Davis, whose research was funded by a grant to UC Davis from the California Walnut Board, said additional research is needed to further explore how walnuts reduce tumor cell growth.
"The bottom line is that what is good for the heart -- walnuts -- may be good for the prostate as well," he said.