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Thyroid dysfunction following radiotherapy for head and neck cancer
S L Turner1, K W Tiver, S C Boyages
1Department of Radiation Oncology, Westmead Hospital, N.S.W., Australia.
International Journal of Radiation Oncology, Biology, Physics
|January 15, 1995
Summary
External beam radiotherapy for head and neck cancers frequently causes hypothyroidism. Routine thyroid function testing is recommended post-treatment to monitor for this common complication.
Area of Science:
- Endocrinology
- Oncology
- Radiotherapy
Background:
- Head and neck cancers are often treated with external beam radiotherapy.
- Thyroid gland radiation can lead to endocrine dysfunction.
- Hypothyroidism is a potential long-term complication of thyroid radiotherapy.
Purpose of the Study:
- To assess the incidence of hypothyroidism after whole-thyroid external beam radiotherapy.
- To evaluate both subclinical and clinical hypothyroidism.
- To determine the frequency in squamous cell cancers of the head and neck.
Main Methods:
- Serum-free thyroxine and thyroid-stimulating hormone levels were measured.
- 104 patients were studied: 84 post-radiotherapy and 20 pre-treatment.
- Data collected between August 1991 and May 1992.
Main Results:
- No pre-treatment thyroid dysfunction observed.
- 23.8% of previously treated patients had hypothyroidism (9.5% subclinical, 14.3% clinical).
- Hypothyroidism risk increases over time, potentially reaching 40% by 5 years; more common with combined laryngectomy and radiotherapy.
Conclusions:
- Hypothyroidism is a frequent complication of head and neck radiotherapy.
- Clinical suspicion was low, highlighting the need for systematic screening.
- Routine thyroid function tests are crucial for post-treatment follow-up.