Medullary Thyroid Carcinoma Detected by Routine Health Screening Had Better Clinical Outcome and Survival

The benefits of early detection in medullary thyroid carcinoma (MTC) are not well established. This study investigates the impact of early detection of MTC on clinical outcomes.

This retrospective study evaluated 144 patients diagnosed with MTC at Samsung Medical Center between 1995 and 2019, classified as asymptomatic (mostly detected through routine health check-ups, including ultrasonography, calcitonin, or carcinoembryonic antigen levels) and symptomatic. Initial treatment response, final clinical outcomes, and cancer-specific survival were compared.

MTC was diagnosed in 104 (72.2%) asymptomatic and 40 (27.8%) symptomatic patients. The symptomatic group showed a significantly larger primary tumor size, more frequent lateral neck lymph node metastasis, more advanced tumor, node, metastasis (TNM) staging, and higher pre- and postoperative serum calcitonin levels. For initial treatment response, the proportion of excellent responders was significantly higher in the asymptomatic group (71.2% vs. 40.0%), while that of patients with biochemical incomplete response (37.5% vs. 26.9%) and structural incomplete response (22.5% vs. 1.9%) was significantly higher in the symptomatic group (all P<0.001). For the final clinical outcomes, the rate of patients with no evidence of disease was higher in the asymptomatic group (67.3% vs. 30.0%), while the rate of patients with structurally identifiable disease was higher in the symptomatic group (45.0% vs. 7.7%) (P<0.001 for both). The symptomatic group had significantly poorer cancer-specific survival than the asymptomatic group (log-rank P=0.023).

Compared with late diagnosis through symptomatic presentation, early diagnosis in asymptomatic patients results in significantly better initial treatment response, final clinical outcomes, and cancer-specific survival in patients with MTC.