Association between physical activity changes and risk of incident ischemic stroke following cancer diagnosis: A nationwide retrospective cohort study

Abstract Background Physical inactivity is prevalent after cancer treatment, which could increase ischemic stroke risk in cancer survivors. This study investigated the association between physical activity change from pre‐ to post‐diagnosis and ischemic stroke risk among cancer survivors. Methods Using data from the Korean National Health Insurance Service database, 269,943 cancer survivors (mean [SD] age, 56.3 [12.1] years; 45.7% male) with no history of cardiovascular disease were evaluated based on changes in physical activity from pre‐ to post‐diagnosis. Using the Fine‐Gray model, subdistribution hazard ratios (sHRs) and 95% confidence intervals (CIs) for ischemic stroke risk were calculated, considering death as a competing risk. Results After cancer diagnosis, 62.0% remained inactive, 10.1% remained active, 16.6% became active, and 11.4% became inactive. During a mean (SD) follow‐up of 4.1 (2.0) years, being active both pre‐ and post‐diagnosis was associated with a 15% decreased risk of ischemic stroke (sHR, 0.85; 95% CI, 0.75–0.96), compared with those who remained inactive. Cancer survivors who became active and inactive post‐diagnosis showed a 16% and 11% lower ischemic stroke risk (sHR, 0.84; 95% CI, 0.75–0.93; sHR, 0.89; 95% CI, 0.79–0.99), respectively, than those who remained inactive. Analysis by the primary cancer site did not substantially differ from the main findings. Conclusions Physical activity is associated with reduced ischemic stroke risk among cancer survivors. The potential benefits of physical activity are not limited to individuals who were physically active before cancer diagnosis, thus preventive strategies against ischemic stroke should emphasize physical activity throughout the cancer journey.