High-Fat Diets Linked to Stage III Colon Cancer Recurrence

August 14, 2007

BOSTON -- After curative surgery and adjuvant chemotherapy for stage III colon cancer, patients who ate a high-fat diet were more likely to have a recurrence than those who ate a so-called prudent diet, researchers here reported.

BOSTON, Aug. 14 -- After curative surgery and adjuvant chemotherapy for stage III colon cancer, patients who ate a high-fat diet were more likely to have a recurrence than those who ate a so-called prudent diet, found researchers here.

Those with a higher recurrence risk ate more meat, fat, French fries, refined grains, and desserts. Jeffrey A. Meyerhardt, M.D., M.P.H., of the Dana-Farber Cancer Institute, and colleagues, reported in the Aug. 15 issue of the Journal of the American Medical Association.

By contrast, a "prudent diet," high in fruits, vegetables, poultry, and fish, had no effect on cancer recurrence or death.

The findings came from a prospective observational study of 1,009 patients with stage III disease enrolled in a randomized adjuvant chemotherapy trial from April 1999 through May 2001. The NCI-sponsored Cancer and Leukemia Group B (CALGB) trial compared with weekly fluorouracil and leucovorin with weekly irinotecan, fluorouracil, and leucovorin.

Previous epidemiological studies have indicated that dietary factors are associated with the risk of developing colon cancer, the researchers wrote. "However, the influence of diet and other lifestyle factors on the outcome of patients with established colon cancer is largely unknown," they added.

It is possible, they said, that after resection of stage III colon cancer, increasing intake of the high-fat and processed foods in the Western diet may facilitate a milieu that allows residual microscopic disease to proliferate and spread.

Also, they said, patients rated high for consumption of foods in the Western diet after diagnosis may have had a similar diet before diagnosis and consequently may have had more biologically aggressive tumors. Nonetheless, there was no significant association between dietary pattern and tumor-related characteristics, the researchers said.

Patients filled out a semiquantitative food frequency questionnaire during and six months after adjuvant chemotherapy. Using factor analysis, the researchers identified two major dietary patterns, the fat-heavy Western diet and the prudent diet. Patients were then followed up for cancer recurrence or death.

During a median follow-up of 5.3 years for the overall cohort, 324 patients had a cancer recurrence, 223 died as a result, and 28 died without documented cancer recurrence.

Compared with patients in the lowest quintile of the Western pattern, those in the highest quintile had a more than three-fold higher risk of cancer recurrence or death (adjusted hazard ratio hazard ratio for disease-free survival, 3.25, 95% confidence interval 2.04-5.19; P for trend

Higher undesirable Western scores were seen among men, whites, and past or current smokers.

In contrast, other characteristics, particularly tumor types known to predict prognosis, did not vary significantly among the quintiles of either dietary pattern, the researchers reported.

The researchers pointed out that they could not completely exclude the possibility that a higher intake of the Western pattern may have reflected other predictors of poor prognosis.

Nevertheless no significant association between diet and predictors associated with cancer recurrence (extent of invasion into bowel wall, number of positive lymph nodes) was observed.

Because the study was observational, causality cannot and should not be drawn from these data, Dr.Meyerhardt wrote. Nonetheless, the data suggest that eating more red and processed meat, sweets and desserts, French fries, and refined grains increases the risk of recurrence and decreases survival.

"Further analyses are under way to better delineate specific nutrients or food groupings that may have the strongest association," the authors concluded.