Background: There is inconsistent evidence on the association between physical activity and pancreatic cancer risk\nand few studies have investigated early life or life-course physical activity. The objective of this study was to\nevaluate the association between trajectories of physical activity across the life-course and pancreatic cancer risk.\nMethods: A population-based case-control study was conducted (2011â??2013) using cases (n = 315) from the\nOntario Pancreas Cancer Study and controls (n = 1254) from the Ontario Cancer Risk Factor Study. Self-reported\nrecall of moderate and vigorous physical activity was measured at three time points: young adulthood (20sâ??30s),\nmid-adulthood (40sâ??50s) and older-adulthood (1 year prior to questionnaire completion). Physical activity\ntrajectories were identified using latent class analysis. Odds ratios (OR) and 95% confidence intervals (CI) were\nestimated from multivariable logistic regression adjusted for covariates: age, sex, race, alcohol, smoking, vegetable,\nfruit and meat consumption, and family history of pancreatic cancer.\nResults: Six life-course physical activity trajectories were identified: inactive at all ages (41.2%), low activity at all\nages (31.9%), increasingly active (3.6%), high activity in young adulthood with substantial decrease (13.0%), high\nactivity in young adulthood with slight decrease (5.0%), and persistent high activity (5.3%). Compared to the\ninactive at all ages trajectory, the associations between each trajectory and pancreatic cancer after confounder\nadjustment were: low activity at all ages (OR: 1.11; 95% CI: 0.75, 1.66), increasingly active (OR: 1.11; 95% CI: 0.56,\n2.21), high activity in young adulthood with substantial decrease in older adulthood (OR: 0.76; 95% CI: 0.47, 1.23),\nhigh activity in young adulthood with slight decrease in older adulthood (OR: 0.98; 95% CI: 0.62, 1.53), and\npersistently high activity (OR: 1.50; 95% CI: 0.86, 2.62). When time periods were evaluated separately, the OR for the\nassociation between high moderate activity in the 20sâ??30s and pancreatic cancer was 0.89 (95% CI: 0.64, 1.25) and\nsome sex differences were observed.\nConclusion: Distinct life-course physical activity trajectories were identified, but there was no evidence that any of\nthe trajectories were associated with pancreatic cancer. Future studies with larger sample sizes are needed to\nunderstand the associations between physical activity trajectories over the life-course and pancreatic cancer risk.
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