Colon cancer survivors who eat a "Western" diet high in red meat, fats and refined grains are more than three times as likely to have a recurrence as those who consume a "prudent" diet high in fish, poultry, fruits and vegetables, researchers said Tuesday.
Scientists already knew that avoiding a Western diet could reduce the risk of contracting colon cancer in the first place, but this is the first study associating the diet with a recurrence of the disease, Dr. Jeffrey A. Meyerhardt and his colleagues at the Dana-Farber Cancer Institute in Boston reported today in the Journal of the American Medical Assn.
Such diets have not been linked to the recurrence of any other type of cancer, with the possible exception of breast cancer, for which there have been conflicting results.
Many physicians have been telling colon cancer survivors to avoid a Western diet, said Dr. Lily Lai of the City of Hope cancer center, who was not involved in the study. The report "at least gives us some data" to support that recommendation, she said.
Colon and rectal cancer combined are the third most common form of cancer among men and women in the United States, with nearly 154,000 new cases each year and 52,000 deaths. It is curable by surgery if caught early, and the incidence has been declining because of increased screening.
Meyerhardt and his colleagues studied 1,109 patients with Stage III colon cancer, which is localized to the large bowel area and the lymph nodes near the tumor. All had received successful surgery and were participating in a clinical trial that added chemotherapy to the regimen.
Their diets were assessed when they entered the trial and six months later. The patients were studied for an average of more than five years.
Overall, 324 patients had a recurrence and 223 died of their cancers.
The team found that the 20% of patients who had the most Westernized diet were 3.25 times more likely to have a recurrence as those with the most prudent diet. Meyerhardt said that he expected to see a difference between the two groups, but that the magnitude of the difference was surprisingly large.
The results, he said, "suggest that people treated for locally advanced colon cancer can actively improve their odds of survival by their dietary choices."
Meyerhardt and his colleagues speculated that a Western diet increased levels of insulin and insulin-like growth factors, which have been linked to the formation and growth of some types of tumors.