Background: Survival studies in differentiated thyroid carcinoma (DTC) may be biased because they have been performed in heterogeneous populations. In addition, specific death causes in DTC have not been documented well in the literature.
Aims: The aim of our study was to investigate survival and specific death causes in a homogeneous cohort of DTC patients.
Patients: Patients included 366 consecutive patients with DTC who had all been treated according to the same protocol for initial therapy and follow-up.
Methods: Prognostic factors for DTC-related death were analyzed by univariate Cox regression analysis, followed by stepwise multivariate Cox regression analysis. Standardized mortality rates (SMR) were calculated using normal mortality rates for the entire Dutch population.
Results: During follow-up of 8.3 +/- 4.6 yr, 82 patients (22.4%) died. At multivariate Cox-regression analysis, tumor stage T4, distant metastases, and advanced age were associated with an increased relative risk for DTC-related death. SMR for the entire group was 2.32. This could be explained by increased SMR in patients with stage T4, distant metastases, or advanced age. Death causes could be verified in 80 patients: 52 died of DTC, 28 due to other causes. Ten of the 20 patients with stage T1-3M0 died from thyroid carcinoma.
Conclusion: Relative risk for thyroid cancer-related death and SMR are significantly increased in patients with stage T4 and M1 or advanced age. Although death risk is not increased in T1-3 M0 patients, DTC contributed significantly to mortality in all patient categories.