Endocrine Abstracts

Background: Total thyroidectomy and cervical lymph node resection is the standard treatment for MTC, as the cancer often occurs in both thyroid lobes and the incidence of lymph node metastasis reaches 80%, especially in patients with palpable tumor. However, previous analyses have included both hereditary and sporadic MTCs. In the ultrasound era, patients are referred for surgery earlier, often with not palpable MTCs, and the result of the germline RET oncogene mutation analysis is achievable before surgery. To date, bilateral tumors have been described in only 10% of sporadic MTCs, so we have undertaken an evaluation of the feasibility of hemithyroidectomy in this group, based on patients treated at our center.

Purpose: Evaluation of the clinical picture of sporadic MTC for the possibility of less radical surgical treatment.

Material and methods: Retrospective analysis of 658 patients with sporadic MTC treated in 2012-2022 at the Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch.

Results: Median age at the time of diagnosis was 58 years (17-85), the women: men ratio was 2,3. Median time of follow up was 4 years (0-12). 73% of tumours were detected incidentally, on imaging studies. Total thyreoidectomy was performed in 90%. Median diameter of primary tumor was 14 mm (1-100 mm). 68% of tumors were up to 2 cm, 10% >4 cm, 2,5% was inoperable due to local invasion or extensive distant metastases. In postoperative material multifocality was found in 10,5%, bilateral tumors in 3%, extrathyroidal invasion in 14%, angioinvasion in 26%. Lymph node metastasis occurred in 28% in the central compartment, in 21% in the ipsilateral lateral compartment and in 4% in the bilateral lateral compartment. Distant metastases were found in 6% at time of diagnosis. The occurrence of metastases in central and lateral neck nodes, and distant sites correlated with primary tumor size, occurring respectively in 10%, 7%, and 2% of tumors <1 cm; 30%, 27%, and 8% of 11-20 mm tumors; 41%, 38%, and 15% of 21-40 mm tumors; and 57%, 68%, and 45% of tumors >4 cm, (P < 0.01). Normalization of serum calcitonine after primary treatment was corelated with CR and achieved in 86% patients with <1 cm tumor, 68% 11-20 mm 57% 21-40 mm and 28% of >4 cm tumors.

Conclusions: Based on our retrospective data, it seems that in patients with non-hereditary MTC cT1aNoMo (based on preoperative ultrasound and genetic test result), lobectomy with central neck lymph nodes can be considered.