Hypothyroidism following radiotherapy for head and neck cancer: multivariate analysis of risk factors.
The incidence of hypothyroidism following radiotherapy for head and neck cancer is 10-45% in several series. In order to identify possible risk factors a multivariate analysis was performed in 221 patients previously treated with either radiotherapy alone or combined with surgery or chemotherapy. Diagnostic procedures included: total T3 and T4, free T4 and TSH measured by radioimmunoassay, and thyroid scintigraphy. The absolute rate of hypothyroidism was 41.17% (subclinical 26.24%, clinical 14.93%). No thyroid nodules were detected in any patient. By multivariate analysis, risk factors that significantly influenced a higher incidence of hypofunction were: high radiation dose (p = 0.000), combination of radiotherapy and cervical surgery (p = 0.003), time from therapy (p = 0.022) and no shielding of midline (p = 0.026).
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Department of Radiation Oncology, Asturias General Hospital, Oviedo, Spain.
D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology / Q000209:etiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011867:Radioisotope Teletherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000009:adverse effects*; D012307:Risk Factors; D013961:Thyroid Gland / Q000528:radiation effects
D003037:Cobalt Radioisotopes