Clinical characteristics and survival of patients with calcitonin-secreting neuroendocrine neoplasms: experience from a series of 71 patients.

PURPOSE: Although calcitonin (CT)-secreting neuroendocrine neoplasms (NENs) represent a relevant differential diagnosis for medullary thyroid carcinoma, the paucity of data makes it difficult to define their prevalence and biology. The purpose of this study was to evaluate important clinical features of CT-secreting NENs. METHODS: We retrospectively analysed all CT-secreting NENs in a series of 1216 patients with NENs of all primary locations treated at a national referral centre over a course of 20 years. We performed necessary laboratory, histopathological, morphological and functional work-up. Statistical analysis was performed with SPSS, with a p value ≤ 0.05 considered as significant. RESULTS: We identified 71 patients with CT-secreting NENs that predominantly originated from the pancreas and lung. The majority of tumours were of a higher grade and were mostly metastatic (91.5%). Almost one-third of the tumours (32.4%) co-secreted another hormone(s). Diarrhoea was rarely present (21.1%) and was not correlated with CT values (p = 0.174). The calcitonin level did not correlate with the Ki67 index but was correlated with the presence of metastatic disease (p = 0.008). The median overall survival was 15.0 ± 4.7 months (95% CI 5.8–24.2). A total of 64.8% of patients had CT values above 100 pg/mL. Although this group had significantly shorter survival (p = 0.048), this was proven to be the effect of more frequent metastatic disease. CONCLUSION: Calcitonin secretion seems to be a marker of more aggressive tumour behaviour. We suggest that CT measurements should be more systematic, at least for pancreatic and lung NENs.