Differentiated thyroid cancer in two European referral centres: impact of different diagnostic and therapeutic strategies.

[OBJECTIVE] To evaluate differences in the presentation, diagnostic/therapeutic approaches, and outcome of differentiated thyroid cancer (DTC) in an Italian and a Dutch referral centre.

[METHODS] We retrospectively included 919 patients (586 Italian, 333 Dutch), and compared the two cohorts as a whole and according to ATA risk classes. Dynamic risk stratification (DRS) and Kaplan-Meier curves were used to compare progression-free survival (PFS) and disease-specific survival (DSS).

[RESULTS] Several differences (P < 0.001) were found in clinicopathological features and in diagnostic/therapeutic modalities. The Dutch cohort had a higher age at diagnosis, a higher number of patients presenting with metastatic disease, and patients with stage III/IV. Most Italian patients showed a low/intermediate ATA risk, while high-risk patients represented half of the Dutch cohort. The Dutch cohort received a more intensive first treatment and more additional treatments during follow-up (i.e. surgery, radiotherapy, and systemic treatments). DRS analysis showed comparable excellent and biochemical incomplete responses, while the Dutch cohort had a lower rate of indeterminate and a higher rate of structural incomplete responses (P < 0.001). The Dutch cohort had a significantly worse 5-year PFS, and TC-related mortality was 10 and 1% for the Dutch and Italian cohorts, respectively, in line with the higher rate of advanced disease at presentation, with DSS still excellent for both.

[CONCLUSION] Data reported in the present comparison between two European countries highlight a different prevalence, presentation, and outcome of DTC, likely due to variabilities in healthcare systems, iodine nutritional status, and diagnostic and treatment approaches.