Thyroid dysfunction after radiotherapy in children with Hodgkin's disease.

Area of Science:

• Pediatric Oncology
• Endocrinology
• Radiation Oncology

Background:

• External beam radiotherapy (XRT) is a common treatment for pediatric Hodgkin's disease.
• The thyroid gland is often within the radiation field, posing a risk for dysfunction.
• Long-term monitoring of thyroid function is crucial in childhood cancer survivors.

Purpose of the Study:

• To investigate the incidence and characteristics of thyroid dysfunction in children treated with radiotherapy for Hodgkin's disease.
• To determine the relationship between radiation dose and the development of thyroid abnormalities.
• To assess factors influencing thyroid dysfunction post-treatment.

Main Methods:

• Prospective measurement of thyroid function in 119 children (≤16 years) post-radiotherapy for Hodgkin's disease.
• Analysis of thyroid stimulating hormone (TSH) levels in relation to radiation dose (≤2600 rad vs. >2600 rad).
• Evaluation of age, sex, chemotherapy, and lymphangiogram (LAG) as potential contributing factors.

Main Results:

• Thyroid abnormalities, primarily elevated TSH (occult hypothyroidism), were significantly higher in children receiving >2600 rad (78%) compared to ≤2600 rad (17%).
• No significant influence of age, sex, or chemotherapy on thyroid dysfunction was observed.
• The mean interval to dysfunction was 18 months (low-dose) and 31 months (high-dose), with most cases appearing within 3-5 years.
• Spontaneous TSH normalization or improvement occurred in a subset of patients.

Conclusions:

• Childhood external neck irradiation for Hodgkin's disease is associated with a dose-dependent risk of occult hypothyroidism.
• Thyroid function monitoring is essential for early detection and management of radiation-induced thyroid dysfunction in pediatric survivors.
• The findings highlight the importance of optimizing radiation doses to minimize long-term endocrine sequelae.