Long-term Clinical Outcomes of Patients With Medullary Thyroid Cancer: A Single Institution, Tertiary Referral Centre Experience.

Aims: Medullary thyroid cancer (MTC) is a rare form of thyroid cancer with a variable disease course. We aimed to conduct a real-world analysis of the clinical outcomes of patients with MTC, thereby providing further insight into the prognosis and management.

Materials And Methods: All patients with MTC whose data were available on electronic patient records since its introduction in 1992 at our institution were collected retrospectively. Data collected include patient characteristics, staging, treatment modalities and survival outcomes. The data extraction cut-off was 31st December 2022. Progression-free survival (PFS) and overall survival (OS) were analysed using Kaplan-Maier curves and log-rank test. The significance threshold was set at p value <0.05.

Results: 164 patients were included in this study. The median age at presentation was 44 years. Majority of patients (61%) presented with advanced disease; 41% were stage IVa, 4% IVb and 16% IVc. The 10-year OS was 92% for stage I-III disease, 77% for stage IVa/b and 38% for stage IVc. Germline rearranged during transfection (RET) mutations were detected in 21% of patients. 98% of patients received primary surgery and 24% received systemic treatment for recurrent/metastatic disease, with a high response rate seen with RET-specific inhibitors in those with RET-mutant MTC. Adjuvant radiotherapy improved locoregional control for those with locally advanced disease (p = 0.001) but failed to translate into OS benefit (p = 0.486).

Conclusion: Survival outcomes observed in our cohort mirror those reported in the literature and highlight the need for improved therapy options, especially in those presenting with metastatic disease. Our data reaffirmed a lack of survival benefit with adjuvant radiotherapy for MTC with a high rate of systemic relapse and future research should focus on evolving mechanisms of resistance to novel tyrosine kinase inhibitors.