Healthy diets linked to better outcomes in colorectal cancer

Colorectal cancer patients who followed healthy diets had a lower risk of death from colorectal cancer and all causes, even those who improved their diets after being diagnosed, according to a new American Cancer Society study.

There are more than 1.4 million colorectal cancer (CRC) survivors in the United States. Previous studies have suggested a strong influence of diet quality in disease outcomes, and that some pre- and postdiagnosis dietary components are related to survival in men and women with CRC. But studies of dietary patterns to assess overall diet quality in relation to overall and CRC-specific mortality are inconsistent, making the development of evidence-based recommendations for CRC survivors difficult.

To learn more, investigators led by Mark A. Guinter, PhD, MPH, American Cancer Society post-doctoral fellow, reviewed data from 2,801 men and women diagnosed with CRC in the American Cancer Society's large, prospective Cancer Prevention Study-II (CPS-II) Nutrition Cohort. They found those whose pre- and postdiagnosis diets were consistent with the American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention had lower all-cause and CRC specific mortality.
Pre-diagnosis diets that most closely aligned with ACS dietary recommendations were associated with a 22% lower risk of all-cause mortality compared to those on the other end of the spectrum. Significant inverse trends were observed for CRC specific mortality, as well. For the highest quartile of pre-diagnosis Western dietary pattern, which is characterized by high intakes of red meat and other animal products, there was a 30% higher risk of CRC death compared with the lowest quartile.
Postdiagnosis dietary patterns were also significantly associated with the risk of death. The highest compared with the lowest ACS-score showed a 65% lower risk of CRC mortality and a 38% lower risk of mortality from all causes.
The study authors say additional diet patterns and scores that also were based on plant foods and low red and processed meat consumption corroborated their main findings. They conclude that the results suggest the importance of diet quality as a potentially modifiable tool to improve prognosis among men and women with CRC.
"This study is this first to our knowledge that considered change in diet quality across the CRC continuum," said Guinter. "These results suggest that high diet quality after diagnosis, even if poor before, may be associated with a lower risk of death."