Adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations and overall mortality among adults with colorectal cancer in a multiethnic cohort study.

29 Background: High adherence to AICR recommendations on diet, adiposity, and physical activity is associated with improved survival among adults with colorectal cancer (CRC). However, over 80% of participants in existing studies self-reported as non-Hispanic White (NHW). We studied the association between adherence to AICR recommendations and overall mortality among adults with CRC in a multiethnic cohort. Methods: This prospective analysis used data from the Multiethnic Cohort (MEC) study. The MEC is a racially/ ethnically diverse cohort of over 200,000 participants residing in Hawaii and Los Angeles. Lifestyle behaviors in the MEC were assessed by questionnaire at enrolment/Q1 (1993-1996) and periodically over follow-up. We included those with incident CRC before completing Q3 (2003-2008). Follow-up was from Q3 survey completion to December 2019. The main exposure was the standardized AICR score [0-7 points] at Q3. The primary outcome was overall mortality; CRC-specific mortality was secondary. We used multivariable Cox proportional hazards regression to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CIs). Results: There were 1127 adults diagnosed with CRC prior to Q3. Of these, 1079 (95.7%) had non-missing data on the AICR score and comprised our study population. Median (IQR) age at diagnosis was 69 (62-75); median (IQR) follow-up was 12.2 (0.1-16.4) years. There were 489 (45.3%) women. By self-reported race/ethnicity, there were: 153 (14.2%) Black/African Americans, 453 (42.0%) Japanese Americans, 79 (7.3%) Latinos, 165 (15.3%) Native Hawaiians, and 229 (21.2%) NHWs. Only 48 (4.4%) adults had high adherence (AICR≥5 points). Those in the highest category of AICR scores (AICR≥4.5) had statistically significant lower risk of overall mortality relative to those in the lowest category (AICR≤2.5) (HR: 0.64, 95% CI, 0.47-0.89). A similar (but non-statistically significant) association was observed with CRC-specific mortality [HR (high vs low): 0.70, 95% CI, 0.31-1.60]. Those who increased their score between Q1&Q3 had lower overall mortality (HR: 0.87, 95% CI,0.79 - 0.96). Similar trends were observed in stratified analysis by race/ethnicity; however, statistical power was limited. Conclusions: High adherence to AICR recommendations was associated with lower risk of overall mortality in this multiethnic population of adults with CRC. Efforts to increase adherence to AICR recommendations in this population are needed.