Similar Stage-dependent Survival and Outcome in Sporadic and Hereditary Medullary Thyroid Carcinoma

CONTEXT: Long-term data are scarce on large cohorts with sporadic (sMTC) and hereditary medullary thyroid carcinoma (hMTC). OBJECTIVES: To compare long-term disease-specific survival (DSS) and outcomes between sMTC and hMTC groups. DESIGN: Retrospective analysis. SETTING: German tertiary referral center. PATIENTS: A total of 673 patients with MTC that underwent surgery from January 1974 to July 2019. INTERVENTION: None (observational study). MAIN OUTCOME MEASURE: Differences between sMTC and hMTC in long-term, stage-dependent survival and outcomes. RESULTS: Surgery was performed at median ages of 49 years for sMTC (n = 477, 44% male) and 29 years for hMTC (n = 196, 43% male; P < 0.0001). The mean follow-up times were 9.2 ± 8.0 (sMTC) and 14.6 ± 10.3 years (hMTC). Age and tumor stage at diagnosis were significantly different between the 2 groups (P < 0.0001). The sMTC and hMTC groups had different overall DSS (log rank, P = 0.0183), but similar stage-dependent DSS (log rank, P = 0.1242-0.8981). In a multivariate analysis, sMTC and hMTC did not differ in DSS (hazard ratio HR = 1.56; 95% CI, 0.94-2.57), but in both groups, a worse DSS was significantly associated with age at diagnosis (HR = 1.04; 95% CI, 1.02-1.05), male sex (HR = 0.49; 95% CI, 0.32-0.76), and stages III and IV at diagnosis (HR = 20.00; 95% CI, 2.74-145.91 and HR = 97.47; 95% CI, 13.07-726.67, respectively). The groups had significantly different (P < 0.0001) outcomes (i.e., cured, minimal residual disease, structural detectable disease, and death), but similar stage-dependent outcomes (P = 0.9449-0.0511), except for stage III (P = 0.0489). CONCLUSION: Patients with sMTC and hMTC had different ages of onset, but similar stage-dependent DSS and outcomes after the MTC diagnosis. This finding suggested that tumor behavior was similar in sMTC and hMTC.