Endocrine Abstracts

Aims: Surgery is the only curative treatment for medullary thyroid cancer (MTC) patients and the gold standard practice is still represented by total thyroidectomy and prophylactic central neck compartment lymphnode dissection. As it happened for differentiated thyroid cancer, in the last years some authors proposed less aggressive and extent surgical modality as hemithyroidectomy and ipsilateral neck compartment dissection in unilateral and solitary sporadic MTC cases. Few studies are available regarding the prevalence of multifocality in MTC and its pre and postsurgical role. Aims of this study were to assess the prevalence of multifocality in familiar and sporadic MTC patients and to correlate the presence of multifocality with clinical and pathological parameters.

Patients and Methods: We retrospectively analyzed data from 389 consecutive MTC patients followed-up at our department from 2005 to 2018. Multifocality was defined as the presence of at least more than one tumoral focus both in the same thyroid lobe or in the contralateral one. Independent sample t-test and chi-squared were used for correlations. A p-value ≤ 0.05 was considered statistically significant. Statistical analysis was performed using 22.0 SPSS statistical package

Results: Multifocality was found in 89/389 cases (22.9%), particularly in 45/311 (14.5%) of sporadic cases and 44/78 (56.4%) of familiar ones. All multifocal tumors were also bilateral in familiar cases, while tumor bilaterality was present in half of sporadic cases (8.7%). When we correlated the presence of multifocality with clinical and pathological features we found a strong correlation with mutated RET (P < 0.001), advanced stage III/IV (P < 0.001), tumor extrathyroidal extension (P < 0.001), presence of neoplastic emboli (P = 0.001), tumor bilaterality (P < 0.001), presence of central neck compartment lymphnode metastases (P < 0.001), younger age at MTC diagnosis (P < 0.001), higher pre-surgical calcitonin levels (P = 0.01). When we analyzed separately the group of familiar and sporadic cases, we found almost the same associations, with the exception of age at MTC diagnosis in both group (P = 0.1 in sporadic and P = 0.3 in familiar cases) and of pre-surgical CT levels in familiar one (P = 0.06). In this last group a correlation was also found between multifocality and with bigger tumor dimension (P = 0.01).

Conclusions: According to our data, as expected, the majority of hereditary cases were multifocal and bilateral, while sporadic cases were multifocal in a rather low percentage of cases (14.5%) and only in a subgroup they were bilateral (8.7%). In the era of personalized medicine, we could start to propose lobectomy in sporadic MTC patients with single intrathyroidal lesions.