Hypothyroidism in older patients with head and neck cancer after treatment with radiation: a population-based study.
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).


CONCLUSIONS
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.
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Grace L
GL
Smith
Benjamin D
BD
Smith
Adam S
AS
Garden
David I
DI
Rosenthal
Steven I
SI
Sherman
William H
WH
Morrison
David L
DL
Schwartz
Randal S
RS
Weber
Thomas A
TA
Buchholz
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016001:Confidence Intervals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology; D015994:Incidence; D008297:Male; D011336:Probability; D016016:Proportional Hazards Models; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects; D012042:Registries; D018426:SEER Program; D012720:Severity of Illness Index; D016019:Survival Analysis