Small medullary thyroid carcinoma: post-operative calcitonin rather than tumour size predicts disease persistence and progression

ObjectiveRecently, small medullary thyroid carcinomas (smallMTCs; ≤1.5 cm) are frequently diagnosed, occasionally as incidental findings in surgical specimens. Their clinical course varies. We examined tumour size as a predictor of clinical behaviour.DesignA retrospective study.MethodsA total of 128 smallMTC patients (35.2% males and 45% familial) were followed up for 0.9–30.9 years. According to tumour size (cm), patients were classified into four groups: group 1, 0.1–0.5 (n=33); group 2, 0.6–0.8 (n=33); group 3, 0.8–1.0 (n=29) and group 4, 1.1–1.5 (n=33).ResultsPre- and post-operative calcitonin levels were positively associated with the tumour size (P