GENETICS, DIAGNOSIS, AND MANAGEMENT OF MEDULLARY THYROID CARCINOMA AND PHEOCHROMOCYTOMA/PARAGANGLIOMA

Objective: Medullary thyroid carcinoma (MTC) and pheochromocytoma/paraganglioma (PHEO/PGL) are rare neuroendocrine tumors. Because of the increased metastatic rates in certain genetic backgrounds, early diagnosis and treatment are essential to improved patient outcomes. Our objective was to summarize recent findings related to the genetics, diagnosis, and management of MTC and PHEO/PGL. Methods: A literature review was performed. Results: MTC is primarily associated with mutations in the rearranged during transfection (RET) protooncogene. Determining the specific genetic mutation can guide patient management and screening. Early detection and appropriate surgical management of MTC is critical to prevent or limit metastatic spread, as treatment options for patients with metastatic disease are limited. PHEO/PGL also has a strong genetic component, with approximately 50% of cases linked to germline and somatic mutations in 15 genes. Although most PHEO/PGLs are benign, factors such as genetic background, size, tumor location, and high methoxytyramine levels are associated with higher rates of metastatic disease. The state-of-the-art diagnosis and localization of PHEO/PGLs is based on measurement of plasma metanephrines and methoxytyramine and functional imaging studies. For both PHEO/PGL and MTC, surgery is the only curative treatment. Treatment options for patients with metastatic disease are limited. Conclusion: As genetic testing becomes more widely available, the diagnosis of MTC and PHEO/PGL will be made earlier due to routine screening of at-risk patients. In addition, continued advances in basic science, diagnostic methods, and imaging techniques will improve understanding of the pathogenesis of these diseases and facilitate the introduction of novel treatment strategies for patients with metastatic disease.