Endocrine Abstracts

Background: Differentiated thyroid cancer (DTC) <1 cm without risk factors require only lobectomy, and there is no need for radioiodine remnant ablation (RRA). The approach for surgery and RRA after surgery is less clearly defined for tumours measuring 1–4 cm.

Objectives: We aimed to evaluate the surgical approaches of DTC in stages pT1–2 in a moderate iodine deficient area. We compared our data to the current European Thyroid Association (ETA,2006) and American Thyroid Association (ATA,2015) clinical practice guidelines.

Methods: Data of 111 DTC patients treated between 2013–2018 at Flór Ferenc Hospital, Kistarcsa were retrospectively analyzed. The therapeutical response could be evaluated in 96 DTC patients.

Results: 81 patients were classified with DTC in stages pT1–2. 64 patients were found in stages pT1, 17 patients were detected in stages pT2. The histological distribution of DTC was 65/81 (80.2%) papillary thyroid cancer (PTC) and 16/81 (19.8%) follicular thyroid cancer (FTC). Lymph node metastases were present in 21.5% of PTC and 0% of FTC. No distant metastases were detected. 25% of pT1 DTC was multifocal (9% limited to one lobe, 16% involved both lobes/isthmus), and 11.7% of pT2 DTC was multifocal (5.8% limited to one lobe, 5.8% involved both lobes). Thus pT1–2 multifocal DTC located in both lobes/isthmus were found in 11 patients (13.5%), all PTC, whereby 4/37 (10.8%) were in stage pT1a, 5/27 (18.5%) were in stage pT1b, 2/17 (11.8%) were in stage pT2. All of them underwent total thyreoidectomy, and in 10 of 11 were done postsurgical RRA. The tumour size in the contralateral lobe was <5 mm in 5 cases, was >5 mm in 3 cases (mean 9.6 mm) and there were no exact data in 3 cases.

Conclusions: In 13.5% of pT1–2 patients (11/81) the tumour involved both lobes, which changes the staging of the disease. The size of the tumour in the contralateral lobe is small in most cases (mean 1.4 mm), this fact makes almost impossible to detect and follow up them by ultrasound. Therefore we suggest total thyreoidectomy in moderate or low iodine supplied areas in T1b–T2 cases to improve the risk stratification, to determine the necessity of RRA and the long-term follow up, which are almost impossible if only lobectomy is being done.