Abstract TP209: Effect of Chemotherapy on Stroke Risk in Cancer Patients

Abstract

Introduction: Chemotherapy may be a cause of cancer-associated stroke, but whether it increases stroke risk remains uncertain. We aimed to clarify the impact of chemotherapy on stroke risk in cancer patients. Methods: We investigated 27,932 patients enrolled in a hospital-based cancer registry at Osaka University Hospital between 2007 and 2015. The registry collects clinical data, including cancer status (site and stage), on all patients treated for cancer. Of them, 19,006 patients with complete data were included. A validated algorithm was used to identify stroke events within 2 years of cancer diagnosis. Patients were divided based on whether their initial treatment plan included chemotherapy. The association between chemotherapy and stroke was analyzed using the Kaplan-Meier method and stratified Cox regression. Results: Of the 19,006 patients, 5,887 (31%) patients were in the chemotherapy group. Non-targeted chemotherapy was used in 5,371 patients. Stroke occurred in 44 patients (0.75%) in the chemotherapy group and 51 patients (0.39%) in the no-chemotherapy group. Kaplan-Meier curve analysis showed that patients in the chemotherapy group had a higher stroke risk than patients in the no-chemotherapy group (HR 1.84; 95% CI 1.23-2.75; Figure [A]). However, this difference was insignificant after adjustment for cancer status using inverse probability of treatment weighting with propensity scores (HR 1.20; 95% CI 0.76-1.91; Figure [B]). Similarly, in the stratified Cox regression model, chemotherapy was not associated with stroke after adjustment for cancer status (HR 1.26; 95% CI 0.78-2.03). These findings were consistent with analysis wherein the effect of chemotherapy was treated as a time-dependent covariate (HR 1.02; 95% CI 0.55-1.88). Conclusions: In this population, the elevated stroke risk in cancer patients who received chemotherapy was presumably due to advanced cancer stage; chemotherapy was not associated with the increased risk of stroke.