Medullary Thyroid Cancer: Single Institute Experience over Three Decades and Risk Factors for Recurrence.

Abstract

Medullary thyroid cancer has a historic recurrence rate up to 50%, and surgery remains the only cure. This study aims to assess factors related to recurrence and metastatic spread in MTC. Retrospective chart review was performed from 1990-2023. Descriptive analysis and regression models were used for analysis. Single specialized tertiary care referral center. 68 patients with MTC, who underwent surgery, were included. Recurrence. Mean age at diagnosis was 54.9years(42.2-64.1), 65%(n=44) females. Lymph node and distant metastases were found in 24%(n=16) and 4%(n=3), respectively. RET mutations were present in 52%(n=35): MTC risk levels Highest 6%, High 7%, and Moderate 39%. Mean tumor size was 1.9cm(1.2-3.2) and mean preoperative calcitonin was 504.4pg/mL(133.2-1833.8). Total thyroidectomy(TT) was performed in 10 patients, TT+central neck dissection(CND) in 28, and TT+CND+lateral neck dissection(LND) in 25. On final pathology, 40% had positive central nodes and 25% had positive lateral nodes. Recurrence was 22%, median follow-up 4.7years(1.2-28.0). Male gender(HR=5.81, p=0.021), positive lateral neck nodes(HR 8.10, p=0.011) and high/highest MTC risk level RET mutations(HR 8.66, p=0.004) were significantly associated with recurrence. Preoperative calcitonin>2,175 pg/mL was a strong predictor for distant metastasis(AUC0.893) and a good predictor for lateral neck disease(AUC0.706). Extent of surgery was not significantly associated with recurrence(p=0.634). One of 4 patients undergoing surgery for MTC will recur. Risk factors associated with recurrence are male gender, lateral LN metastasis and high/highest MTC risk level mutations, but not necessarily surgery type. Preoperative calcitonin>2,175 pg/mL is suggestive of advanced disease and should prompt further evaluation.