Extent of thyroid resection and thyroid function after postoperative radiotherapy following total laryngectomy or total pharyngo-laryngo-esophagectomy.

OBJECTIVE: Concurrent chemoradiotherapy (CCRT) is often performed after total pharyngo-laryngo-esophagectomy (TPLE) or total laryngectomy (TL). Hypothyroidism is one of the side-effects of CCRT. The objective of this study was to ascertain the timing of onset and severity of latent hypothyroidism among patients who underwent radiotherapy (RT) or CCRT after TPLE or TL, using thyroid-stimulating hormone (TSH) as a biomarker, and to explore methods of preventing its development.

METHODS: Participants comprised 21 patients who underwent these treatments at Tokyo Medical University Hachioji Medical Center between May 2009 and December 2013. TSH, free thyroxine 3, and free thyroxine 4 levels were used as indicators of thyroid function, and thyroid hormone was administered for TSH levels ≥15 µU/mL.

RESULTS: Post-radiotherapeutic TSH levels in 17 of the 21 patients (81%) were not within the reference value, and 10 (48%) required thyroid hormone therapy. Pharmacotherapy was initiated within 1 year in 5 of these 10 patients (50%), and between 1 and 3 years in the remaining 5 patients. No patient who did not undergo thyroidectomy required hormone therapy. Early evaluation of thyroid function appears important when postoperative RT, including CCRT, is performed in combination with TPLE or TL.

CONCLUSION: Our study suggested that postoperative CCRT or RT after TPLE or TL, especially hemithyroidectomy, carries a high risk for hypothyroidism.