Radiation-induced complication after radiotherapy in patients with head-and-neck cancers

Background: Exposure of nontarget organs such as the thyroid gland (as a normal and high radiosensitive tissue) to radiation during radiotherapy for patients with head-and-neck cancers remains unavoidable. Hypothyroidism is the most common radiation side effect on the thyroid gland. In this study, we used the parameters of thyroid gland (triiodothyronine [T3], thyroxine [T4], and thyroid-stimulating hormone [TSH]) measurements before and after radiotherapy for patients with head-and-neck cancers. Materials and Methods: In the first step, descriptive statistics for predictors and response variables were performed. In the next step of data analysis, a multivariate linear mixed-effects model was fitted simultaneously for three response variables in order to study the trend of thyroid gland parameters. Results: The results indicated that there was a significant decreasing trend in TSH from 1.74 at baseline to 0.65 at the end of the study, and there was a significant increasing trend in T4 from 8.63 at baseline to 9.38 at the end of the study. Conclusions: There were significant changes in thyroid gland parameters after radiotherapy treatment for patients with head-and-neck cancers. Thus, preventative strategies are needed to reduce this complication. The patients with head-and-neck cancers who received radiotherapy treatment should be evaluated regularly and repeatedly during the radiotherapy treatment period.