Hypothyroidism after radiotherapy

M. F. Ronjom, C. Brink, L. Hegedus, J. Overgaard, Jørgen Johansen

Research output: Contribution to journalConference abstract in journalResearchpeer-review


Introduction: Radiation-induced hypothyroidism (RIHT) is a well-known late effect after radiotherapy (RT) to the neck in head and neck squamous cell carcinoma (HNSCC), Hodgkin lymphoma, and breast cancer. Objectives: To investigate the reported incidence and risk factors for development of RIHT as well as normal tissue complication probability (NTCP) models and dose constraints for radiation treatment planning. Methods: Review of the literature on RIHT and data extraction from our studies of two independent cohorts of patients with HNSCC treated with definitive RT without surgery. Results: Subclinical hypothyroidism has been reported in 24-50 % and overt hypothyroidism in 6-20 % of patients. We found an estimated 5-year incidence of biochemical hypothyroidism of 26 %. A high radiation dose to the thyroid gland and a small volume were significant risk factors for RIHT, which is supported by other studies. In the literature, surgery to the neck and sex have also been found to be significant risk factors whereas chemotherapy does not seem to be of importance in patients with HNSCC. NTCP models taking both thyroid volume and mean dose to the gland have been proposed for prediction of RIHTas well as threshold values for thyroid dose for RT planning. Conclusions: Radiation-induced hypothyroidism is a frequent late effect after RT to the neck. Surgery, radiation dose, and thyroid volume seem to affect the risk of RIHT. Considering the frequency of RIHT and the possible consequences of hypothyroidism, thyroid dose constraints are needed in RT planning. Furthermore, thyroid function should be monitored after RT to the neck.
Original languageEnglish
Article numberIS-05
JournalSupportive Care in Cancer
Issue numberSUPPL. 1
Pages (from-to)S24
Number of pages1
Publication statusPublished - 2015
EventMASCC/ISOO International Symposium - Bella Center, Copenhagen, Denmark
Duration: 25. Jun 201527. Jun 2015


SeminarMASCC/ISOO International Symposium
LocationBella Center

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