Endocrine Abstracts

Medullary thyroid carcinoma (MTC) early spreads to cervical lymph nodes and to distant sites: mostly to the liver, lungs or bones. Unusual sites such as breast, skin or orbit have been also described. The aim of the study was to evaluate the frequency, localisation of unusual metastases of MTC and their impact on survival.

Eligibility criteria for this study were the presence of a pathological confirmed diagnosis of MTC with distant metastases (other than lymph nodes) and a follow-up of at least one visit between January 1st 2000 and May 1st 2010 in 7 University French hospitals.

We retained 102 patients (men/women: 57/45; multiple endocrine neoplasia (MEN) 12.7%; median age at MTC diagnosis: 50.5 yr). At the end of the study, 68.6% patients had bone metastases, 64.7% pulmonary metastases, 59.8% liver metastases. Unusual sites, diagnosed in 21 patients (20.6%), were brain, skin, pancreas, breast, peritoneum, adrenals, prostate, retina, and endometrium. Sex ratio, age at MTC diagnosis, proportion of MEN, tumor staging and calcitoninemia or ECA of metastatic patients with unusual sites were not statistically different from those of other patients. On May 1st 2010, 50 patients (49.0%) were alive, and 45 patients (44.1%) were deceased (data not available for 7 patients). The 10-year overall survival was 55.5% years after MTC diagnosis. Survival of patients with unusual metastases was 54.4% (no significant difference compared with the remaining population).

In a French population of 102 cases of distant metastatic MTC, the frequency of unusual metastases was 20.6%. These metastases were not associated with specific characteristics of patients and had no impact on 10-year survival. These metastases have to be localised in case of elevated calcitoninemia without lymph nodes, lung, bone or liver metastases.