Late side effects in the thyroid gland in association with transforming growth factor β1 (TGF-β1) levels in patients with head and neck cancers treated with radiation therapy

Introduction. Radiotherapy and radiochemotherapy are, besides surgery, common treatments for head and neck cancers. Despite using advanced modern radiation techniques, the late side effects are a serious problem. From a multitude of cytokines and growth factors shown to contribute to the injury process after cancer therapy, transforming growth factor β1 (TGF-β1) is among the most fundamental ones. The study evaluated if a high level of TGF-β1 before, during, and after treatment can predict thyroid gland fibrosis, which causes hypothyroidism, one of the common late side effects of head and neck cancer irradiation. Material and methods. Fifty-six patients with head and neck cancer who underwent radiation alone or concomitant chemoradiotherapy were included in the study. Analyzed variables included thyroid stimulating hormone (TSH), volume and echogenicity of the thyroid gland, and the level of TGF-β1. Results. In comparison to the initial level, statistically significant increased levels of TSH and statistically significant decreased volume of the thyroid gland were observed 6 and 12 months after irradiation. Moreover, statistically significant decreased levels of TGF-β1 were observed one month after irradiation. High levels of TGF-β1 before treatment or changes in TGF-β1 levels during and after treatment influenced changes neither in TSH levels nor in volume and echogenicity of the thyroid gland one year after radiotherapy. Conclusions. Early evaluation of TSH after radiation is needed to predict hypothyroidism. High TGF-β1 levels before and changes during and after radiation cannot predict hypothyroidism one year after treatment.