Background: In patients with head and neck cancer, radiation treatment (RT) is a risk factor for hypothyroidism. However, the specific magnitude of risk after RT in older patients is not known.
Methods: We identified 5916 patients (age > 65 years) from SEER-Medicare diagnosed with head and neck cancer from 1992 to 2002. Proportional hazards models compared hypothyroidism risk after any RT versus surgery alone.
Results: In patients treated with RT, 5-year incidence of hypothyroidism was 20% and 10-year incidence was 59%; in patients treated with surgery alone, incidence was 7% and 39% (p < .001). Patients treated with RT had increased adjusted risk (hazard ratio [HR] = 2.14; 95% confidence interval [CI] = 1.74-2.62), persisting for up to 10 years of follow-up (HR = 1.85, 95% CI = 1.39-2.44 from 5 to 10 years).
Conclusion: In older patients with head and neck cancer, RT is associated with elevated hypothyroidism risk. As onset may be delayed for years, patients may require lifelong thyroid function screening after treatment.
Copyright 2009 Wiley Periodicals, Inc.