Mammograms for women in their 40s?

Should all women in their 40s be routinely screened for breast cancer? Not necessarily, according to the American College of Physicians. In a new set of guidelines for clinicians of 40-something patients, the group recommends that mammography screening decisions be made on a case-by-case basis. It advises clinicians to discuss the benefits and harms of screening with the patient, as well as each woman's individual cancer risk and preference about screening.

The organization based its recommendations, which will be published in the April 3 issue of Annals of Internal Medicine, on a rigorous review of evidence showing there is variation in the benefits and harms associated with mammography among women in their 40s. The American College of Physicians is the leading professional organization for internal medicine specialists, with a membership of 120,000.

"There are important benefits to screening mammography, but we believe the decision to be screened should be based on an informed conversation between a patient and her physician," said health policy expert Douglas K. Owens, MD, MS, a researcher with the Veterans Affairs Palo Alto Health Care System and a professor of medicine at the Stanford University School of Medicine, who chaired the committee that developed the guidelines. "In our view, the evidence doesn't support a blanket recommendation for women in this age group."

Breast cancer is the second-leading cause of cancer related death among women in the United States; according to the American Cancer Society, 25 percent of all diagnosed cases are among women younger than age 50. Among these younger women, the risk of breast cancer varies greatly - from less than 1 percent for a 40-year-old woman with no risk factors to 6 percent for a 49-year-old woman with multiple risk factors, which include family history of breast cancer, older age at the birth of her first child and younger age at the onset of menstruation.

Physicians and medical groups have for years debated the merits of screening mammography for women in their 40s. While it is well-established that mammography reduces mortality from breast cancer in 50- to 70-year-old women - and that women in this age-group should be routinely screened - the evidence isn't as clear-cut for younger women.

Five years ago, the U.S. Preventive Services Task Force, an independent panel of experts in primary care and prevention, examined data from numerous clinical trials and estimated that screening mammography every one or two years in women in their 40s resulted in a 15 percent decrease in breast cancer mortality after 14 years of follow-up. But a separate Canadian study published in the same issue of the journal found that women in this age-group received no benefit from mammography.

Past analyses have also made note of the potential harms of screening, including radiation exposure, procedure-associated pain, false-positive results, over-diagnosis and potentially unnecessary treatment.

Based in part on the conflicting evidence, medical groups have differing screening recommendations for women under age 50. The U.S. Preventive Services Task Force and the American College of Obstetricians and Gynecologists both recommend screening mammography every one to two years for women in their 40s, while the 2006 American Cancer Society guideline recommends yearly mammograms starting at age 40.

Because of the ongoing controversy, the American College of Physicians' Clinical Efficacy Assessment Subcommittee decided to take its own look at the evidence related to screening in women in their 40s. After their review, the group concluded that screening mammography for women in this age group likely provides a modest reduction in breast cancer mortality, but - as with any screening intervention - it also comes with the risk of potential harms. Based on this, it recommended that clinicians:

Periodically perform individualized assessment of risk for breast cancer to help guide decisions about screening mammography

Inform women ages 40 to 49 of the potential benefits and harms of screening mammography

Base screening mammography decisions on benefits and harms of screening as well as a woman's preferences and breast cancer risk profile

In the new guidelines, the organization emphasizes the importance of using a woman's concerns about breast cancer and screening to help guide decision-making about mammography. Women's thoughts about mammography or their risks of developing breast cancer will likely vary greatly, the group notes, but it expects the potential reduction in breast cancer mortality associated with screening to outweigh other considerations for many women.

"We still think many women will choose to get mammography, and we're supportive of that," said Owens. "The most important thing is that women be well-informed about the decision they're making."