Incidental T1 stage medullary thyroid carcinoma: The effect of tumour diameter on prognosis and therapeutic implications.

For incidental MTC with tumour diameter ≤ 1.0 cm and without distant metastasis, if there is no significant increase in serum calcitonin level after surgery and ret proto-oncogene (RET) gene mutation is negative, it may be not necessary to perform completion thyroidectomy immediately.