Several hypotheses have been proposed to explain the development of thyroid collision tumors, including the predisposing theory, the stem cell theory, the random collision theory, and the hostage theory (neoplastic coercion).[3,6,11] Given the pivotal role of genetic alterations in TC, some studies have suggested a potential relationship between RET proto-oncogenes and collision tumors of MTC and PTC.[12] However, none of these theories fully account for the phenomenon, and a comprehensive understanding may require an integrative approach combining elements from multiple theories. The gene discussed is RET; the disease is medullary thyroid gland carcinoma.