Prognostic factors in differentiated thyroid cancer—a 20-year surgical outcome study

AIMS: The aim of this study was to determine prognostic factors in patients operated on for well-differentiated thyroid cancer (WDTC). PATIENTS AND METHODS: A retrospective cohort study of patients with WDTC treated at our institution between 1989 and 1991 (n = 97; mean age 52.3 years, 78 females, follow-up 124.6 ± 75.1 months) was made. Multivariate analysis was performed including: age, gender, size of primary tumor, location and number of foci in thyroid tissue, clinical stage, thyroid capsule infiltration, tumor histological type, extent of surgery, prognosis based on the AGES and MACIS scores, and tumor proliferative activity based on determination of proliferating cell nuclear antigen (PCNA) and Ki-67 expression in tumor tissue and nodal metastases. RESULTS: The multivariate analysis showed increased relative risk (RR) of death for: age above 60 years (7.39; p < 0.001), pTm (2.94; p = 0.002), pT3 (11.83; p < 0.001), and pN1 (4.11; p < 0.001). Total thyroidectomy decreased RR of death (0.39; p = 0.023) when compared to more limited resections. Moderate and high PCNA index was associated with 48.3% and 87.5% mortality, respectively, while Ki-67 index was associated with the highest mortality rate (76%) in the group of medium values. CONCLUSIONS: Despite good prognosis in WDTC, factors that most significantly affect overall survival rate include age, size of primary lesion and multifocal disease, presence of nodal metastases, and extent of primary surgery.