Risk of Stroke in Cancer Survivors: A Meta-analysis of Population-Based Cohort Studies.

Objective: Accumulating evidence suggests that cancer survivors may have a relatively higher risk of stroke. The aim of this meta-analysis was to determine whether cancer survivors have a relatively higher risk of stroke than cancer-free populations on the basis of published data from population-based cohort studies.

Methods: PubMed, Embase, and Cochrane Library were searched from inception to February 8, 2020, for population-based cohort studies. Effect estimates with 95% confidence intervals (CIs) were pooled using the random-effects model. We conducted subgroup analyses and meta-regression to explore sources of heterogeneity and the stability of the results.

Results: Twenty population-based cohort studies involving 10,479,530 participants were identified. Overall, the relative risk (RR) for stroke in cancer survivors was 1.66 (95% CI 1.35-2.04; < 0.001) compared with that in cancer-free controls; survivors of head and neck, hematologic, lung, pancreas, and stomach cancer (all < 0.05) showed consistently significant results, whereas no significant increased risk was observed for patients with other cancer types. The effects were more prominent in cancer survivors with female sex (RR 1.38, 95% CI 1.18-1.61; < 0.001), younger age at cancer diagnosis (<45 years) (RR 2.57, 95% CI 1.27-5.19; = 0.009), and shorter cancer survival duration (≥1-2 years) (RR 1.69, 95% CI 1.18-2.42; = 0.004). Moreover, cancer survivors had a significantly increased risk of ischemic stroke (RR 1.53, 95% CI 1.28-1.84; < 0.001) compared with hemorrhagic stroke.

Conclusions: Cancer plays a critical role in the etiologic of stroke. Due to the existence of substantial heterogeneity among the included studies, the results should be interpreted with caution. However, early prevention and effective intervention of stroke in cancer survivors require attention from health policy makers.