Marine ω-3 polyunsaturated fatty acid and fish intake after colon cancer diagnosis and survival: CALGB 89803 (Alliance)

Background: Marine ω-3 polyunsaturated fatty acids (PUFAs), primarily found in dark fish, may prevent colorectal cancer progression, in part through inhibition of prostaglandin-endoperoxide synthase 2 (PTGS2). However, data in humans are limited. Methods: We examined marine ω-3 PUFAs and fish intake and survival among 1,011 colon cancer patients enrolled in Cancer and Leukemia Group B 89803 between 1999 and 2001 and followed through 2009. Diet was assessed during and 6 months after chemotherapy. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for disease-free (DFS), recurrence-free (RFS), and overall survival (OS). Results: We observed 343 recurrences and 305 deaths (median follow-up: 7 years). Patients in the highest vs. lowest quartile of marine ω-3 PUFA intake had an HR for DFS of 0.72 (95% CI, 0.54–0.97; P trend = 0.03). Individuals who consumed dark fish ≥1/week versus never had longer DFS (HR 0.65; 95% CI, 0.48–0.87; P -value = 0.007), RFS (HR 0.61; 95% CI, 0.46–0.86; P trend = 0.007), and OS (HR 0.68; 95% CI, 0.48–0.96; P trend = 0.04). In a subset of 510 patients, the association between marine ω-3 PUFA intake and DFS appeared stronger in patients with high PTGS2 expression (HR 0.32; 95% CI, 0.11–0.95; P trend = 0.01) compared with patients with absent/low PTGS2 expression (HR 0.78; 95% CI, 0.48–1.27; P trend = 0.35; P interaction = 0.19). Conclusions: Patients with high intake of marine ω-3 PUFAs and dark fish after colon cancer diagnosis may have longer DFS. Impact: Randomized controlled trials examining dark fish and/or marine ω-3 PUFA supplements and colon cancer recurrence/survival are needed. Cancer Epidemiol Biomarkers Prev; 27(4); 438–45. ©2018 AACR .