Performing an immediate completion thyroidectomy may not be necessary for certain incidental T1 stage medullary thyroid carcinomas (MTCs), according to a new study published in Clinical Endocrinology.

“For incidental MTC with tumor diameter ≤ 10 mm and without distant metastasis, if there is no significant increase in serum calcitonin level after surgery and RET gene mutation is negative, it may be not necessary to perform completion thyroidectomy immediately,” said the authors from the First Hospital of China Medical University in Shenyang.

Survival analysis revealed a significant difference in the effect of tumor diameter on prognosis. The rate of lymph node metastasis was lower in patients with tumor diameter ≤5 mm in comparison to patients with tumor diameter >5 mm. However, survival analysis indicated that only tumor diameter >10 mm had a significant impact on the prognosis of patients with T1 stage MTC.


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Regardless of the tumor diameter, the authors found no difference between total thyroidectomy and less than total thyroidectomy in disease-specific survival of patients with T1 stage MTC. Moreover, multivariate analysis identified distant metastasis as the only risk factor affecting the survival of patients with T1 stage MTC.

“It is necessary to subdivide T1 stage and individualize treatment for incidental MTC patients with different tumor diameters,” the authors said.

The retrospective study included data from 908 patients (mean age at the time of diagnosis, 52.94±18.17 years, 67.51% female) diagnosed with T1 stage MTC. Multifocality and lymph node metastasis were observed in 26.76% and 20.26% of the patients, respectively, whereas 1.76% had distant metastasis. Most (99.01%) patients underwent surgical treatment.

Incidental MTC is rare, with most cases being discovered through intraoperative or postoperative pathological diagnosis.

Reference

Gui Z, Wang Z, Xiang J, et al. Incidental T1 stage medullary thyroid carcinoma: the effect of tumor diameter on prognosis and therapeutic implications. Clin Endocrinol. Published online February 22, 2022. doi:10.1111/cen.14702