# Is hemithyroidectomy enough? Low risk of occult contralateral disease in sporadic medullary thyroid cancer

## TL;DR

This study suggests that hemithyroidectomy may be a safe option for some patients with sporadic medullary thyroid cancer, as the risk of hidden disease in the other lobe is low.

## Contribution

The study provides evidence that occult contralateral disease is rare in sporadic medullary thyroid cancer when preoperative ultrasound is used effectively.

## Key findings

- No cases of occult contralateral disease were found in the study.
- Hemithyroidectomy may be a safe alternative for selected patients with favorable tumor characteristics.
- Persistent postoperative calcitonin elevation strongly predicts recurrence.

## Abstract

Total thyroidectomy (TT) remains the standard surgical treatment of sporadic medullary thyroid cancer (sMTC), primarily due to the presumed risk of occult contralateral disease. However, recent evidence suggests that in selected patients, hemithyroidectomy (HT) may offer comparable oncologic outcomes. This retrospective study aimed to evaluate the prevalence of occult contralateral disease and to identify clinicopathological factors associated with disease-free survival (DFS).

We retrospectively analyzed all surgical patients with sMTC at a tertiary academic center (2013–2025), excluding patients with hereditary MTC, RET mutations, or clinical evidence of MEN2. Kaplan-Meier analysis with logrank testing was used to identify predictors of DFS.

Forty-eight patients were included (66.7% female, median age 60.5 years). TT was performed in 44 patients (91.7%). Bilateral disease was present in five patients (11.4%), all detected on preoperative ultrasound. No cases of occult contralateral disease were found. During a median follow-up of 3.4 years, seven patients (14.6%) experienced recurrence. Advanced T stage, nodal involvement, distant metastases, lymphatic and vascular invasion, extracapsular extension, and male sex were all significantly associated with reduced DFS (all p < 0.05). Persistent postoperative calcitonin elevation (> 2 pg/mL) strongly predicted recurrence (p < 0.001), whereas baseline calcitonin > 500 pg/mL did not.

Occult contralateral disease in sMTC is rare when high-quality preoperative ultrasound is available. In selected patients with unifocal, node-negative tumors and favorable pathology, HT combined with structured calcitonin monitoring may be an oncologically safe, less morbid alternative. These findings support individualized, risk-adapted surgical strategies in sMTC. Prospective validation is warranted.