Increased risk of cerebrovascular mortality in head and neck cancer survivors aged ≥ 65 years treated with definitive radiotherapy: a population-based cohort study.

Background: To investigate the relationship between radiotherapy (RT) and the risk of cerebrovascular mortality (CVM) in head and neck cancer (HNC) survivors aged ≥ 65 years.

Methods: Patients with HNC survivors aged ≥ 65 years diagnosed between 2000 and 2012 were included from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier analysis, Log-rank tests, and Cox proportional-hazards regression models were performed for statistical analyses.

Results: We included 16,923 patients in this study. Of these patients, 7110 (42.0%) patients received surgery alone, 5041 (29.8%) patients underwent RT alone, and 4772 (28.2%) patients were treated with surgery and RT. With a median follow-up time of 87 months, 1005 patients died with cerebrovascular disease. The 10-years CVM were 13.3%, 10.8%, and 11.2% in those treated with RT alone, surgery alone, and surgery plus RT, respectively (P < 0.001). The mean time for CVM was shorter in RT alone compared to surgery alone and surgery plus RT (52 months vs. 56-60 months). After adjusting for covariates, patients receiving RT alone had a significantly higher risk of developing CVM compared to those receiving surgery alone (hazard ratio [HR] 1.703, 95% confidence interval [CI] 1.398-2.075, P < 0.001), while a comparable risk of CVM was found between those treated with surgery alone and surgery plus RT (HR 1.106, 95% CI 0.923-1.325, P = 0.274). Similar trends were found after stratification age at diagnosis, gender, tumor location, and marital status.

Conclusions: Definitive RT but not postoperative RT can increase the risk of CVM among older HNC survivors. Long-term follow-up and regular screening for CVD are required for HNC patients who received definitive RT to decrease the risk of CVM.