Acute Thyroid Profile Changes During External Beam Irradiation of Neck

Area of Science:

• Oncology
• Endocrinology
• Radiotherapy

Background:

• Head and neck cancer radiotherapy frequently involves significant thyroid gland irradiation.
• A notable percentage of patients develop hypothyroidism following this treatment.
• Acute, less-defined thyroid function changes post-irradiation warrant further investigation.

Purpose of the Study:

• To investigate acute changes in thyroid function after radiotherapy for head and neck cancer.
• To define the temporal dynamics of thyroid hormone (T3, T4) and TSH levels post-irradiation.

Main Methods:

• Thyroid function tests (T3, T4, TSH) were measured at multiple time points: pre-treatment, 4 weeks post-irradiation, end of treatment, 1 month post-treatment, and 4 months post-treatment.
• Repeated measures ANOVA with Greenhouse-Geisser correction was employed to analyze changes over time.
• Post hoc analysis utilized Bonferroni correction to identify specific interval differences.

Main Results:

• Statistically significant differences in mean T3, T4, and TSH levels were observed across the measured time points.
• Post hoc tests confirmed significant variations in T3, T4, and TSH values at specific intervals.
• External irradiation at therapeutic doses alters thyroid function, leading to an increase in TSH within normal ranges to maintain thyroxine levels.

Conclusions:

• External beam radiotherapy significantly impacts thyroid function in head and neck cancer patients.
• Thyroid function adjusts to a new equilibrium post-irradiation, characterized by elevated TSH levels.
• Monitoring thyroid function is crucial for managing potential hypothyroidism after head and neck radiotherapy.