Colon cancer survivors who eat a so-called "Western diet" high in red meat, dairy, sugar and refined flours are more than three times as likely to have their cancer return or to die from it than those who avoid such foods, finds a study in the Journal of the American Medical Association.
Previous studies had shown that a high-fat diet, especially one with lots of red meat, may increase a person's risk of developing colon cancer. This was the first to show how diet affects whether colon cancer returns in people previously treated for it.
Researchers at Dana-Farber Cancer Institute looked at 1,009 patients with Stage 3 colon cancer that had been treated with both surgery and chemotherapy. Stage 3 colon cancer is cancer that has spread from the large bowel area to the lymph nodes but not other organs.
The researchers questioned the patients on their diets during their chemotherapy treatment period and then 6 months after. Their health was then monitored for five years.
Among the group, 324 patients saw their cancer return, while 223 patients died with cancer recurrence.
The researchers found that those who most closely followed a Western diet were three-and-a-half times more likely to have colon cancer recur than those whose diets were more "prudent" and included high intakes of fruits and vegetables, poultry, and fish.
No relationship was found between the prudent diet and colon cancer recurrence or death.
"The message is that patients in this category can improve their prospects by avoiding certain foods," commented the study's lead author, Dr. Jeffrey Meyerhardt, of Dana-Farber.
Investigators speculate that a "Western" diet leads to increased insulin levels and insulin-like growth factors, which have been linked to the formation and growth of some types of tumours.
Meyerhardt adds that more research is needed to better understand what components of the Western diet are most responsible for the study findings.
