We examined whether performing a hemithyroidectomy with central neck dissection on patients who are phenotypically and clinically considered sporadic impacts the likelihood of achieving biochemical remission.

Materials
A continuous retrospective study included 710 patients with histologically confirmed medullary carcinoma (MC) who underwent initial surgery in 2010-2023 at SPbU Hospital. Germline RET mutations were tested in 64.0% of cases, with 95.0% of these tests conducted postoperatively. Among those tested, 25.3% had the RET mutation.
According to national guidelines, the initial treatment for medullary thyroid cancer involves a thyroidectomy with central neck dissection. However, to minimize potential complications, patients with phenotypically sporadic medullary thyroid cancer were offered hemithyroidectomy with bilateral central neck dissection. "Phenotypically sporadic" were defined as those with unilateral thyroid nodules or all nodules cytologically tested. Patients with bilateral lesions, coexisting pheochromocytoma, or a family history of medullary thyroid cancer (MTC) were treated as having a hereditary form. Primary hyperparathyroidism without signs of multiglandular disease was not considered, given its relatively high prevalence in the general population.
In 157 cases (22.1%), the final extent of thyroid resection was hemithyroidectomy.
Results
72,4% of all patients available for follow-up get biochemical remission. Of them, only 2,5% were pN1a and 0.6% – pN1b. (OR – 13,5). After hemithyroidectomy with neck dissection rate of biochemical remission was 72.86%, and after thyroidectomy with neck dissection, 72.35% . Also, we did not find any differences within progression-free survival.
Conclusion
The decision on the operation volume can be made in a consensus between the surgeon and the patient before the genetic study results are obtained based on the initial presentation.
This approach enables us to assess the tumor's RET status first and, upon detecting a mutation, test non-thyroid samples for its presence to identify inherited forms.