Young nasopharyngeal cancer patients with radiotherapy and chemotherapy are most prone to ischaemic risk of stroke: a national database, controlled cohort study

Objectives This population-based cohort study investigated the ischaemic stroke risk of patients with nasopharyngeal carcinoma (NPC) by treatment. Design Controlled cohort study. Setting Based on claims data of National Health Research Insurance Database in years 19962010. Participants A total of 4615 patients with nasopharyngeal carcinoma newly diagnosed in 20002003 were divided into three subgroups: patients received radiotherapy only, patients received both radiotherapy/chemotherapy and patients received neither radiotherapy nor chemotherapy (non-radio/chemotherapy). They were compared with 36919 reference persons without stroke and cancer, frequency matched with demographic characteristics. Main outcome measures Study subjects were followed up until 2010 to measure ischaemic stroke incidences. Risks associated with treatment and comorbidity were evaluated using Cox proportional hazards regression analysis incorporated with the competing risk of deaths. Results Ischaemic stroke incidence rates were approximate to 2-fold higher in nasopharyngeal carcinoma patients with radiotherapy, radiotherapy/chemotherapy and non-radio/chemotherapy than in references (13.8, 12.8 and 12.6 versus 6.07 per 1000 person-years, respectively). The risk was much higher for 20- to 39-year-old nasopharyngeal carcinoma patients with radiotherapy/chemotherapy [hazard ratio (HR) 14.7, 95% confidence interval 9.2423.4]. Hypertension, diabetes, hyperlipidaemia and alcoholism also enhanced the risk with hazard ratios ranging from 2.4 to 9.3. The overall adjusted ischaemic stroke risk was higher in nasopharyngeal carcinoma patients with the two types of treatment than those without, but not significant. Conclusions Patients with nasopharyngeal carcinoma are at an elevated risk of ischaemic stroke, without significant difference among treatment modalities. The relative risk is more prominent in younger patients. Comorbidity may enhance the risk.