Neuroendocrine tumors producing calcitonin: characteristics, prognosis and potential interest of calcitonin monitoring during follow-up.

Abstract

Inappropriate calcitonin (CT) release, a major feature of medullary thyroid cancer (MTC), may occur in neuroendocrine tumors (NETs). The aims of this retrospective study were to assess i) the characteristics and prognosis of CT-producing NETs, and ii) the value of CT monitoring during follow-up. All patients with NETs in whom serum CT was assayed between 2010 and 2012 were included. MTCs were excluded. Clinical, biological, and histological characteristics were studied. Twenty-one (12%) of 176 patients in whom serum CT was systematically assayed had concentrations >100 ng/l, with tumours predominantly of bronchial or pancreatic origin (P<0.0001), and of high grade (P=0.0006). Poor prognosis was linked to high CT levels, poor differentiation, and grade 3. In a total group of 24 patients with serum CT >100 ng/l, symptoms potentially attributable to CT were recorded in eight, with occasional overlap with the carcinoid syndrome among other secretory syndromes. Immunohistochemistry could be performed in six tumor specimens, CT being detected in five. In 11 patients with five or more successive CT assays, hormone levels were fairly well correlated with clinical courses. Serum CT levels may be raised in some patients with NETs, especially from foregut origin, and of high grade. The suggested value of CT monitoring during follow-up must be confirmed in further studies.