Clinical presentation and outcomes of medullary thyroid cancer in two European countries: impact of diagnostic strategies.

Objective: To evaluate differences in clinical presentation, diagnostic and therapeutic modalities, and outcomes in two cohorts of patients with sporadic medullary thyroid carcinoma (MTC) from reference centres in Italy and the Netherlands. The two centres have different diagnostic approaches, including the use of routine calcitonin (CT) measurement. Methods: A total of 165 patients (106 Italian and 59 Dutch) were retrospectively included. The cohorts were compared overall and according to diagnostic modality. Logistic regression and multivariable Cox proportional hazards models were used, as appropriate, to assess progression-free survival (PFS), disease-specific survival (DSS) and associated risk factors. Results: The Dutch cohort presented with more advanced disease, as per higher TNM, AJCC staging, and significantly higher CT both preoperative and at last visit (P < 0.001). Dutch patients received more frequently second operations, radiotherapy, and systemic treatments. PFS and 10-year DSS were significantly lower in the Dutch cohort (P < 0.001 and P 0.01). Tumour size, nodal involvement, presence of distant metastases at diagnosis and progression during the follow-up were independent strong predictors of shorter PFS and DSS. Patients diagnosed via routine CT measurement showed a less aggressive presentation and more favourable outcome. Conclusion: We compared for the first time two MTC cohorts from countries with different diagnostic and therapeutic approaches. Our data contribute to highlighting an association between routine CT measurement and MTC presentation and outcome, while suggesting that caution should be exercised when interpreting the differences among countries in MTC prevalence and clinical features.