This study aims to define the optimal surveillance strategy for children exposed to radiotherapy by assessing the incidence, risk factors, and timing of thyroid nodules and differentiated thyroid cancer. It also investigates the genetic features of thyroid tumors in this population to identify predictive biomarkers of onset, malignancy, and aggressiveness. Ultimately, the goal is to support more personalized management, including tailored surgery and targeted therapies.

This study aims to improve our understanding of how best to monitor children who have been exposed to radiotherapy, a group known to be at higher risk of developing thyroid nodules and differentiated thyroid cancer (DTC). Current pediatric guidelines are not fully consistent in defining the most appropriate surveillance strategy for these patients. By implementing an early and intensive clinical and ultrasound follow-up, the study seeks to provide clearer evidence on how frequently thyroid abnormalities occur, which factors increase the risk, and when these conditions typically arise after radiotherapy. The ultimate goal is to define a surveillance approach that enables early detection while remaining practical, cost-effective, and mindful of the emotional burden placed on young oncology patients.

Another important focus of the study is the genetic characterization of thyroid tumors in children exposed to radiotherapy. Evidence supporting the use of molecular testing in the diagnostic and therapeutic management of pediatric thyroid cancer is still limited. By analyzing genetic biomarkers in both cytological and histological samples, the study aims to explore their role in predicting the development, malignancy, and aggressiveness of thyroid tumors. These findings could help pave the way toward more personalized care, supporting more conservative surgical approaches when appropriate and facilitating the use of targeted therapies.

INCLUSION CRITERIA

For the group of oncologic patients who underwent radiotherapy:

• Radiotherapy for an oncologic condition performed between January 1, 1999, and December 31, 2018;
• Age at the time of radiotherapy < 18 years;
• Follow-up of at least 4 years conducted at the Endocrine-Metabolic Diseases Program, Pediatric Unit, IRCCS AOU Bologna;
• Obtained informed consent

For the group of subjects not exposed to radiotherapy and without specific risk factors for DTC:

• No history of exposure to ionizing radiation;
• No specific risk factors for DTC (autoimmune thyroiditis, familial forms, genetic syndromes);
• Thyroid ultrasound performed between January 1, 1999, and December 31, 2018, at the Nuclear Medicine Unit of IRCCS AOU Bologna;
• Age at the time of the thyroid ultrasound < 18 years;
• Obtained informed consent

EXCLUSION CRITERIA:

For the group of oncologic patients who underwent radiotherapy:

• Patients transferred to another center before completing 4 years of follow-up after radiotherapy at the Pediatric Unit of IRCCS AOU Bologna, without having received a diagnosis of thyroid cancer.

For the group of subjects not exposed to radiotherapy and without specific risk factors for DTC:

• None.

• Oncologic patients who underwent radiotherapy during childhood between January 1, 1999, and December 31, 2018, with a follow-up of at least 4 years at the Pediatric Unit of IRCCS AOU Bologna.
• Subjects not exposed to radiotherapy and without specific risk factors for differentiated thyroid cancer (DTC), who had a thyroid ultrasound performed during childhood at the Nuclear Medicine Unit of IRCCS AOU Bologna between January 1, 1999, and December 31, 2018.