Adherence to World Cancer Research Fund/American Institute for Cancer Research Guidelines and Mortality Among Participants with Colorectal Cancer in the MEC Cohort.

Background: Racial and ethnic minority patients with colorectal cancer (CRC) are underrepresented in studies on health behavior and mortality.

Methods: We examined the association between post-diagnosis health behavior and mortality in the Multiethnic Cohort (MEC), a diverse group of 215,000 participants from Hawai'i and Los Angeles (recruited 1993-1996). Follow-up was through December 31, 2019. Post-diagnosis health behavior was assessed using a modified World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) score (excluding ultra-processed foods). The primary outcome was overall mortality; CRC-specific mortality was secondary.

Results: Among 1,079 eligible participants, 489 (45.3%) were women, and 850 (78.8%) self-identified as racial/ethnically minoritized people. Over a median follow-up of 12.2 years, there were 613 all-cause deaths and 105 CRC-related deaths. Median time from diagnosis to questionnaire completion was 5 years (interquartile range, IQR: 2-8). Higher WCRF/AICR scores (4.5-7) were associated with lower risk of overall mortality compared to lower scores (≤2.25) (HR: 0.63; 95% CI: 0.45, 0.87). Risk of CRC-specific mortality was also lower but not statistically significant. Among individual health behaviors, physical activity was associated with lower risk of all-cause and CRC-specific mortality (reference: <75 min/week), with HRs of 0.59 (95% CI: 0.43, 0.81) for 75-<150 min/week and 0.51 (95% CI: 0.41, 0.64) for ≥150 min/week.

Conclusions: Higher adherence to WCRF/AICR guidelines, particularly engaging in moderate-to-vigorous physical activity, was associated with lower risk of mortality in long-term CRC survivors.

Impact: These findings support the generalizability of prior studies examining adherence to WCRF/AICR guidelines to a broader group of patients with CRC.