Pre-diagnosis diabetes, life-course body mass index and physical activity, and pancreatic cancer survival in older adults

Background Diabetes and excess body-weight are established risk factors for pancreatic ductal adenocarcinoma (PDAC); however, few studies have evaluated their association with PDAC survival. None have examined pre-diagnosis body size and physical activity across the adult life-course with PDAC survival. Methods We evaluated survival by pre-diagnosis self-reported diabetes, and adult life-course body mass index (BMI, kg/m2) and leisure-time physical activity (LTPA) from late adolescence to older age. We determined trajectories for BMI and LTPA using latent-class modeling. We included 2,522 participants diagnosed with PDAC in the National Institutes of Health (NIH)-AARP cohort between 1996 and 2018. Vital status was followed through December 31, 2019. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for PDAC survival using multivariable Cox proportional hazard models. Significance tests were 2-sided. Results Diabetes (vs without diabetes) was associated with reduced PDAC survival (HR = 1.36; 95% CI: 1.17, 1.59) with similar associations by sex. BMI and LTPA and their trajectories were not associated with PDAC survival. Among patients with unknown cancer stage (n = 1385), compared to low-normal BMI (≥18.5-<22.5), obesity at age 18 (HR = 1.56; 95% CI: 1.09, 2.22) and high normal, overweight, and obese BMI at ages 51-70 (HRs=1.33-1.56) were associated with reduced PDAC survival. Conclusions Pre-diagnosis diabetes was associated with reduced PDAC survival. Life-course BMI and LTPA were not associated with PDAC survival overall. Higher early- and older-adulthood BMIs were associated with poorer survival among unstaged patients; however, stage is an important determinant of survival that we were unable to control for in this group.