Increased Risk of Ischemic Stroke After Radiotherapy on the Neck in Patients Younger Than 60 Years

Abstract

PURPOSE: To estimate the risk of ischemic stroke in patients irradiated for head and neck tumors. PATIENTS AND METHODS: The incidence of ischemic stroke was determined in 367 patients with head and neck tumors (162 larynx carcinomas, 114 pleomorphic adenomas, and 91 parotid carcinomas) who had been treated with local radiotherapy (RT) at an age younger than 60 years. Relative risk (RR) of ischemic stroke was determined by comparison with population rates from a stroke-incidence register, adjusted for sex and age. Other risk factors for stroke (hypertension, smoking, hypercholesterolemia, diabetes mellitus [DM]) were registered. The median follow-up time after RT was 7.7 years (3,011 person-years of follow-up). RESULTS: Fourteen cases of stroke occurred (expected, 2.5; RR, 5.6; 95% confidence interval [CI], 3.1 to 9.4): eight in patients with laryngeal carcinoma (expected ,1.56; RR, 5.1; 95% CI, 2.2 to 10.1), four in pleomorphic adenoma patients (expected, 0.71; RR, 5.7; 95% CI, 1.5 to 14.5), and two in parotid carcinoma patients (expected, 0.24; RR, 8.5, 95% CI, 1.0 to 30.6). Five of six strokes in patients irradiated for a parotid tumor occurred at the ipsilateral side. Analysis of other risk factors for cerebrovascular disease showed hypertension and DM to cause an increase of the RR after RT. After more than 10 years’ follow-up, the RR was 10.1 (95% CI, 4.4 to 20.0). The 15-year cumulative risk of stroke after RT on the neck was 12.0% (95% CI, 6.5% to 21.4%). CONCLUSION: This is the first study to demonstrate an increased risk of stroke after RT on the neck. During medical follow-up, preventive measures should be taken to reduce the impact of the risk factors for cerebrovascular disease, to decrease stroke in these patients.