Abstract
Background and purposeHypothyroidism is a recognized late adverse event following radiotherapy for head and neck cancer (HNC). In the JCOG1008 trial, we treated patients with high-risk HNC with postoperative chemoradiotherapy. We aimed to elucidate factors associated with hypothyroidism by analyzing the JCOG1008 data. Materials and methodsIn 2012–2018, 261 patients from 28 institutions were enrolled in JCOG1008. Thyroid function tests were conducted to assess hypothyroidism, including free thyroxine (FT4) and thyroid-stimulating hormone assays. Hypothyroidism was defined as Grade 2 or higher in CTCAE v4.0. Various clinical and dosimetric parameters were analyzed. In radiotherapy, there were no dose constraints for the thyroid. Multivariable analysis was conducted on these variables to identify predictive factors for hypothyroidism. ResultsThe analysis included 162 patients (57 with 3D-CRT and 105 with IMRT), with a median follow-up of 4.7 years (0.3–9.3 years). Among these, 27 (16.7 %) developed hypothyroidism within 2 years after radiotherapy. In a multivariable analysis, the weekly cisplatin [OR=7.700 (CI: 1.632–36.343, p = 0.010)] and baseline FT4 [OR=0.009 (CI: <0.001–0.313, p = 0.010)] were significantly associated with hypothyroidism in the IMRT group. Regarding dosimetric characteristics, V60Gy [OR=1.069 (CI: 0.999–1.143, p = 0.054)] was potentially associated with the development of hypothyroidism. ConclusionThe study revealed that the incidence of hypothyroidism within 2 years after postoperative chemoradiotherapy for high-risk HNC was 16.7 % based on analytical results from prospective clinical trials.
Published Version
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