The impact of the extent and time of operation on the survival in patients with differentiated thyroid carcinoma (DTC)

INTRODUCTION: To analyze the impact of time and extent of operation on overall and disease-free survival in patients with differentiated thyroid carcinoma (DTC). MATERIAL AND METHODS: Retrospective analysis of 1235 DTC patients, a representative probe of patients diagnosed or treated between 1986 to 1998 was performed. 277 patients were staged T1M0 and 958 ones staged > T1M0. 10-year outcomes were analyzed by Kaplan-Meier survival curves and Cox proportional-hazard model. RESULTS: The T1M0 patients were characterized by the best overall and disease-free survival independently of the time and the extent of operation (98% and 96% respectively); in > T1M0 group the survival was better in patients who were treated by total thyroidectomy (94% and 68% respectively) than in patients treated by non-total thyroidectomy (78% and 47% respectively). In patients treated by completion of total thyroidectomy delayed more than 1 year post cancer diagnosis the incidence of carcinoma in postoperative pathological material was twice as high in comparison to the group in whom total thyroidectomy was performed within the first year of therapy (p = 0.000). CONCLUSIONS: 1. In differentiated thyroid carcinoma the prognosis is related to the extent of operation only in patients staged more than T1M0. 2. A delay > 12 months in completion surgery in patients with differentiated thyroid cancer (tumors > 1 cm of diameter) significantly increases the risk of progression of multifocal disease in thyroid remnants.