CHANGING THE PARADIGM: LOBECTOMY FOR SPORADIC MEDULLARY THYROID CANCER.

Objectives: Total thyroidectomy is the treatment of choice for medullary thyroid cancer (MTC) though the sporadic forms are usually monocentric. Aim of the present study was to evaluate a) the performance of calcitonin (Ct) levels, ultrasound scans (US), and cytology 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 89 RET germline negative patients diagnosed with MTC in the last 30 years, treated with total thyroidectomy ± lymphadenectomy, and followed in our Tertiary Care Center. In a subgroup of 55 patients, divided in those with a mono- or bilateral goiter, we applied ex-post criteria for the pre-surgical identification of the lobe holding the MTC nodule.

Results: Only 2/89 patients (2.2%) had a bilateral MTC at histology. A strongly significant correlation was found between preoperative basal Ct levels and MTC size. According to the ex-post identification criteria, the 84.4% and 56.5% of the nodules would have been identified preoperatively as MTC, in monolateral and bilateral goiters respectively.

Conclusions: This is the first European study that aims to evaluate the feasibility of lobectomy as first line therapy for MTC based on the evaluation of thyroid US, and serum Ct levels. These tools have been shown to have a good accuracy in detecting the affected lobe and strongly support the possibility to perform a more conservative surgery to treat RET-negative patients with suspicious MTC and nodular goiter.