Association of Dietary Patterns With Cancer Recurrence and Survival in Patients With Stage III Colon Cancer

While dietary factors have been implicated in the risk of developing colon cancer, it is not clear whether diet influences the outcome in patients who have established disease. This question was addressed in a prospective observational study of 1009 patients with stage III colon cancer who enrolled in a randomized trial of adjuvant chemotherapy in 1999–2001. Participants were asked to complete a semiquantitative food frequency questionnaire midway in the course of chemotherapy and again about 6 months after adjuvant therapy ceased. Two major dietary patterns emerged: a prudent pattern with high intakes of fruits and vegetables, poultry, and fish; and a Western pattern with high intakes of meat, fat, refined grains, and deserts. The median follow-up interval was 5.3 years. Recurrent disease developed during follow-up in 324 patients, and 223 of them died with recurrent disease. Another 28 patients died without documented recurrent disease. Higher intake of a Western dietary pattern following diagnosis of colon cancer was associated with significantly worse disease-free survival. Compared with patients in the lowest quintile of the Western pattern, those in the highest quintile had an adjusted hazard ratio (AHR) for disease-free survival of 3.25 (95% confidence interval [CI], 2.04–5.19). The AHR for recurrence-free survival was 2.85 (95% CI, 1.75–4.63). For overall survival, the AHR associated with intake of a Western dietary pattern was 2.32, with a 95% CI of 1.36–3.96. The reduced disease-free survival associated with a Western diet was not significantly altered when adjusted for gender, age, lymph node stage, body mass index, level of physical activity, performance status at baseline, or treatment group. The prudent dietary pattern, in contrast, was not significantly associated with recurrent cancer or cancer mortality. The AHR for disease-free survival, comparing the highest and lowest quintiles of the prudent dietary pattern, was 1.20 (95% CI, 0.83–1.75). There also was no relationship between the prudent pattern and either recurrence-free survival or overall survival. The investigators believe this to be the first study in a potentially cured group of colon cancer survivors to analyze the effects of diet. Further studies hopefully will identify those elements of a Western dietary pattern that are most closely associated with an adverse outcome.