Endocrine Abstracts

JOINT3474

Introduction: Thyroid cancer survivors, particularly those with papillary carcinoma, have an increased risk of developing a second primary cancer, including colorectal cancers. This heightened risk may be attributed to genetic, environmental factors, or prior treatments such as radioactive iodine therapy. We present the case of a patient who developed a lower rectal adenocarcinoma seven years after undergoing thyroidectomy for papillary carcinoma, highlighting the importance of vigilant surveillance in thyroid cancer survivors.

Case Report: A 43-year-old woman with no family history of cancer was diagnosed with papillary thyroid carcinoma in 2015, for which she underwent a total thyroidectomy followed by radioactive iodine therapy. In 2022, she presented with rectal symptoms, including rectal bleeding and tenesmus, leading to the diagnosis of a lower rectal adenocarcinoma. A colonoscopy confirmed the presence of a rectal tumor, and biopsy results showed a poorly differentiated, infiltrating adenocarcinoma. The patient underwent surgical resection followed by adjuvant chemotherapy and radiotherapy.

Discussion: This case highlights the increased risk of second primary cancers in survivors of thyroid cancer. Numerous studies have shown that patients with papillary thyroid carcinoma are at a higher risk for developing colorectal cancers. For instance, a meta-analysis by Berthe et al. reported an elevated risk of second primary cancers, including colorectal cancer, in these patients. Likewise, Rubino et al. observed a significant association between thyroid cancer and colorectal cancers. The underlying mechanisms could involve shared genetic mutations, hereditary syndromes, or side effects from radioactive iodine treatment.

Conclusion: Thyroid cancer survivors, particularly those with papillary carcinoma, should undergo close surveillance to detect second primary cancers, especially colorectal ones, at an early stage. Genetic evaluation and regular screening are crucial for these patients to ensure early detection and better outcomes.