在普通人群中，既往缺血性中风 (IS) 是随后发生缺血性中风的危险因素；目前尚不清楚这种关系在癌症患者中是否仍然存在。我们的目标是检查新诊断癌症个体既往 IS 与未来 IS 风险之间的关联。我们对新诊断的成年癌症患者（不包括非黑色素瘤皮肤癌和原发性中枢神经系统肿瘤）进行了一项基于人群的回顾性匹配队列研究2010年至2020年在加拿大安大略省；将既往患有 IS 的患者按照年龄、性别、癌症诊断年份、癌症分期和癌症部位与无中风病史的患者进行匹配 (1:4)。创建累积发生率函数曲线来估计 IS 的发生率。计算了次分布调整风险比 (aHR) 和 95% CI，其中死亡被视为竞争事件。针对不平衡的基线特征对多变量分析进行了调整。我们检查了 65±525 名癌症患者，其中 13±070 名有 IS 病史。中位随访时间为 743 天（四分位数范围，177-1729 天）。在既往有 IS 的队列中，癌症诊断后 IS 的发病率为 261.3/10 000 人年，在没有既往 IS 的人群中为 75.3/10 000 人年。与没有病史的人相比，既往患有 IS 的个体在癌症诊断后患 IS 的风险增加（aHR，2.68 [95% CI，2.41-2.98]）；他们还有更普遍的心血管危险因素。与无 IS 病史的患者相比，妇科癌症 (aHR, 3.84 [95% CI, 2.15-6.85]) 和肺癌 (aHR, 3.18 [95% CI, 2.52-4.02]) 中风风险最高亚组。 IS 的风险与既往卒中的滞后时间呈负相关；那些在癌症诊断前 1 年患有 IS 的人风险最高（aHR，3.68 [95% CI，3.22-4.22]）。在新诊断出癌症的个体中，有 IS 病史的人在诊断癌症后发生中风的可能性几乎高出 3 倍。癌症诊断，特别是如果诊断前中风发生在癌症诊断前 1 年内。

Previous ischemic stroke (IS) is a risk factor for subsequent IS in the general population; it is unclear if this relationship remains true in patients with cancer. Our objective was to examine the association between previous IS and risk for future IS in individuals newly diagnosed with cancer.We conducted a retrospective population-based matched cohort study of newly diagnosed adult cancer patients (excluding nonmelanoma skin cancers and primary central nervous system tumors) in Ontario, Canada from 2010 to 2020; those with prior IS were matched (1:4) by age, sex, year of cancer diagnosis, cancer stage, and cancer site to those without a history of stroke. Cumulative incidence function curves were created to estimate the incidence of IS. Subdistribution adjusted hazard ratios (aHRs) and 95% CIs were calculated, where death was treated as a competing event. Multivariable analysis was adjusted for imbalanced baseline characteristics.We examined 65 525 individuals with cancer, including 13 070 with a history of IS. The median follow-up duration was 743 days (interquartile range, 177-1729 days). The incidence of IS following cancer diagnosis was 261.3/10 000 person-years in the cohort with prior IS and 75.3/10 000 person-years in those without prior IS. Individuals with prior IS had an increased risk for IS after cancer diagnosis compared with those without a history (aHR, 2.68 [95% CI, 2.41-2.98]); they also had more prevalent cardiovascular risk factors. The highest risk for stroke compared with those without a history of IS was observed in the gynecologic cancer (aHR, 3.84 [95% CI, 2.15-6.85]) and lung cancer (aHR, 3.18 [95% CI, 2.52-4.02]) subgroups. The risk of IS was inversely correlated with lag time of previous stroke; those with IS 1 year before their cancer diagnosis had the highest risk (aHR, 3.68 [95% CI, 3.22-4.22]).Among individuals with newly diagnosed cancer, those with IS history were almost 3× more likely to experience a stroke after cancer diagnosis, especially if the prediagnosis stroke occurred within 1 year preceding cancer diagnosis.