Hypothyroidism in patients treated with radiotherapy for head and neck carcinoma: standardised long-term follow-up study.

OBJECTIVE: Hypothyroidism is a common complication when radiotherapy is part of the treatment for head and neck tumours. This study aimed to show the incidence of hypothyroidism and possible risk factors in these patients.
METHODS: Factors related to the population, tumour, treatment and occurrence of hypothyroidism were analysed in 241 patients diagnosed with head and neck carcinoma.
RESULTS: Approximately 53 per cent of patients were diagnosed with radiation-induced hypothyroidism. Its occurrence was related to: tumour location, laryngeal surgery type, neck dissection type, post-operative complications, cervical radiotherapy and radiotherapy unit type (linear particle accelerator or telecobalt therapy technology).
CONCLUSION: Control of thyroid function should be standardised for several years after treatment, particularly in patients with risk factors, such as those treated with telecobalt therapy, those with post-operative complications and for whom the thyroid parenchyma is included in the irradiated area (laryngeal or pharyngeal location and bilateral cervical radiation).