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 1996-2010. PARTICIPANTS: A total of 4615 patients with nasopharyngeal carcinoma newly diagnosed in 2000-2003 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 36 919 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 ≈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 9.24-23.4]. 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.
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 1996-2010. PARTICIPANTS: A total of 4615 patients with nasopharyngeal carcinoma newly diagnosed in 2000-2003 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 36 919 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 ≈2-fold higher in nasopharyngeal carcinomapatients 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 carcinomapatients with radiotherapy/chemotherapy [hazard ratio (HR) 14.7, 95% confidence interval 9.24-23.4]. 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 carcinomapatients 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.