Endocrine Abstracts

Objectives: Multicentric and bilateral tumour foci, usually associated to C cells hyperplasia, are typical of familial medullary thyroid cancer (MTC). On the other hand, sporadic forms are often monocentric. Thus, the question arises if total thyroidectomy is the best option for sporadic MTC, as currently suggested by International guidelines. In this context, a growing body of evidence, mostly coming from Asia, seems to support the possibility of a more conservative surgery. The main obstacle to this conservative approach could be the difficulty in preoperatively diagnose an MTC nodule, especially in Countries with a high prevalence of multinodular goitres. Aim of the present study was to evaluate: a) the performance of calcitonin (Ct) levels, ultrasound scans (US), and fine needle aspiration cytology (FNAC) in the preoperative identification of MTC and b) the number of total thyroidectomies that could have been avoided being the location of the MTC diagnosed preoperatively.

Materials and methods: We retrospectively analysed patients diagnosed with MTC in the last 30 years, treated with total thyroidectomy±lymphadenectomy, and followed in our Tertiary Care Hospital. Only patients with negative RET testing, histological report and at least one among pre-operative US, cytology (by FNAC), pre-operative Ct levels, and adequate follow up, were included (n = 79).

Results: Among the 79 patients with full clinical history, females were the 73.4% and the median age at diagnosis was 62 years. Median pre-operative basal Ct was 134 pg/ml, and median MTC size at histological evaluation was 11 mm. A strongly significant correlation was found between basal Ct levels and MTC size (P-value 0.000003). Only 3/79 (3.8%) patients had a bilateral MTC at histology. US was available in 51 patients, 26 of them (51%) had no nodules reported in the contralateral lobe, and histology confirmed in all cases (100%) the presence of a monolateral MTC, as preoperatively identified. In patients with bilateral nodules (n = 25), US correctly identified the lobe including the MTC in 12 cases (48%). Cytological result was positive or suspicious for MTC or malignancy in 32/50 (64%) FNAC performed on the nodule subsequently diagnosed as MTC at histology.

Conclusions: This is the first European study evaluating the feasibility of lobectomy±lymphadenectomy for MTC. We showed that US is a reliable tool to identify MTC pre-operatively even in a population with a high prevalence of multinodular goitre, and cytology diagnosed MTC in 64% of cases. In our cohort at least 51% of patients could have been initially treated with a more conservative surgery. Since pre-operative Ct levels strongly correlate with tumour volume, they can be used to identify the nodule to be submitted to FNAC.