Endocrine Abstracts

Introduction: The increasing risk of thyroid cancer (TC) in patients who underwent radiotherapy is well documented, especially at early ages. In our center, young patients undergoing cancer treatments are referenced to Endocrine Rehabilitation Clinics (ERC). Their risks are initially identified and monitored regularly. We intended to analyze the characteristics and outcomes of patients who developed post-radiotherapy TC.

Methods: Medical records of patients registered in ERC who underwent radiotherapy and developed TC were reviewed.

Results: Ten patients (seven females) were identified. Primary diagnoses: five Hodgkin’s lymphoma, one abdominal lymphosarcoma, three acute lymphoblastic leukemia and one medulloblastoma, mean age at primary diagnosis 9±5.6 years. Radiotherapy sites: one cervical, four cervico-mediastinic, one abdominal, one total body irradiation, two CNS, one CNS + neuro-axis; mean RT dose: 24±8.4 Gy; mean age at last treatment: 10±5.5 years. None showed thyroid dysfunction. Average time until the first thyroid nodule: 14±4.7 years; seven patients with a dominant nodule and three with ≥2 nodules; mean nodule’s size increment: 2.4±1.6 mm/year. First cytology results: six colloid nodules, two papillary thyroid carcinoma (PTC), one follicular neoplasm and one unknown. Colloid nodule ctyologies were reviewed by a pathologist who found no differences from patients without radiotherapy history. Seven patients underwent total thyroidectomy and three thyroidectomy+lymphadenectomy; mean age at surgery: 27.9±9.2 years. All patients with histology of PTC: eight in stage I and two in II. Iodine-ablation therapy was performed in all patients. Currently, they’re all in remission. Median follow-up from primary to histological diagnosis of PTC: 20 years; median PTC follow-up: 3 years.

Conclusion: TC is a late radiotherapy complication, even when the gland is not directly irradiated. These cancer survivors must be regularly monitored once these nodules are at high risk of malignancy.