'Refined' grains implicated in colon cancer recurrence

by Josh Sosland
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CHICAGO — The risk of colon cancer recurrence is strongly associated with foods that make up the Western diet, including refined grains, according to a study published Aug. 15 in the Journal of the American Medical Association.

The study, "Association of Dietary Patterns with Cancer Recurrence and Survival in Patients with Stage 3 Colon Cancer," found that patients with the highest (top quintile) intake of Western diet foods "experienced a tripling in risk of recurrence or death" compared with the lowest intake.

The study was published by a team led by Jeffrey A. Meyerhardt of the Department of Medical Oncology, Dana-Farmer Cancer Institute, Boston.

The authors noted that a considerable body of research already had established a link between diet and the development of colon cancer.

"However, the influence of diet and other lifestyle factors on the outcome of patients with established colon cancer is largely unknown," they said.

The recurrence study was patterned on the earlier studies of the connection between developing colon cancer and eating a western diet or eating a "prudent" diet. Earlier studies found a significant increased risk of developing colon cancer among people with a higher intake of a Western diet, characterized by higher intakes of red meats, processed meats, sweets/desserts, french fries and refined grains. By contrast, the earlier studies found that the prudent diet, characterized by higher intakes of fruits, vegetables, legumes, fish, poultry and whole grains, was nonsignificantly associated with a reduced risk of developing colon cancer.

The 1,009 patients in the study were enrolled in a chemotherapy study at the National Cancer Institute and were enrolled between April 1999 and May 2001. Dietary and lifestyle questionnaires were given to participants four months after their surgery and then 10 months later. The food frequency questionnaires were developed by a team led by Walter Willett of the Harvard School of Public Health and asked about intake of 131 food items and vitamin and mineral supplements. The survey asked about exact cereal eaten for breakfast or vegetable oil used for frying or baking.

The median follow-up from when the first questionnaire was completed was 5.3 years. Of the 1,009 patients, 324 had experienced recurrences and 223 had died. Another 28 died without documented recurrence. The patients in the study had stage 3 cancer, meaning that the cancer had reached lymph nodes but had not metastasized more broadly through the body.

Patients with the highest intakes of Western diet foods "had a significant increase in the risk of cancer recurrence or mortality, and this relationship remained largely unchanged after adjusting for other predictors of cancer recurrence," the study said.

Pitted against patients with the lowest Western dietary pattern quintile, those in the highest quintile were 3.25 times more likely to suffer a recurrence. Those in the second highest quintile were 1.64 times more likely to experience a recurrence.

By contrast, a similar examination of the effects on the same group of their "prudent" diet intake failed to find a significant association with patient outcome. In effect, the researchers found that eating more "unhealthy foods" was associated with a higher risk of recurrence but that eating more "healthy foods" was not associated with reducing the risk of recurrence.

"When we added the prudent diet into the multivariate model for the Western diet, we continued to observe a significantly worse outcome with increasing intake of Western dietary pattern," the researchers said. "Furthermore, the prudent dietary pattern did not modify the effect of the Western dietary pattern."

Importantly, the researchers said further studies are under way to "better delineate specific nutrients or food groupings that may have the strongest associations."

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