Diet quality and all-cause and cancer-specific mortality in cancer survivors and non-cancer individuals: the Multiethnic Cohort Study.

PURPOSE: We examined post-diagnostic diet quality in relation to all-cause and cancer-specific mortality among adults diagnosed with invasive cancer between cohort entry (45-75 years) and their 10-year follow-up, in comparison with those without invasive cancer during that period, in the Multiethnic Cohort. METHODS: Data were from 70,045 African Americans, Native Hawaiians, Japanese Americans, Latinos, and Whites (6370 with cancer, 63,675 without cancer). Diet quality was measured by the Healthy Eating Index (HEI)-2015, the Alternative HEI-2010 (AHEI-2010), the alternate Mediterranean Diet (aMED), and the Dietary Approaches to Stop Hypertension (DASH) scores, using a food frequency questionnaire. Multivariable Cox models estimated the association of the dietary indexes at 10-year follow-up and changes since baseline with subsequent mortality. RESULTS: Post-diagnostic scores from all four indexes were associated with lower mortality: for the highest vs. lowest quartiles, hazard ratio (HR) for all-cause mortality was 0.74 (95% CI 0.67-0.82) for HEI-2015, 0.82 (0.74-0.92) for AHEI-2010, 0.74 (0.66-0.84) for aMED, and 0.82 (0.74-0.91) for DASH. The corresponding HRs for cancer mortality were 0.84 (0.71-1.00), 0.85 (0.71-1.00), 0.71 (0.59-0.85), and 0.84 (0.71-1.00). Compared to stable scores over 10 years (< 0.5 SD change), HR for all-cause mortality was 0.87 (0.79-0.97) for ≥ 1 SD increase in HEI-2015 and was 1.22 to 1.29 for ≥ 1 SD decrease in scores across the four indexes. These HRs were similar to those for participants without cancer. CONCLUSION: Post-diagnostic high-quality diet was related to lower all-cause and cancer mortality among adult cancer survivors, with risk reduction comparable to that among participants without cancer.