Prognostic factors in follicular carcinoma of the thyroid--a multivariate survival analysis

Multivariate studies of the diagnosis, treatment and prognosis of patients with follicular carcinoma of the thyroid gland are relatively scarce. The aim of our multivariate analysis was to study the factors associated with survival of patients with follicular carcinoma in Slovenia, in an iodine-deficient region.

This retrospective study was carried out in a group of 154 patients (113 women, 41 men; median age 61 years) with follicular carcinoma of the thyroid treated at the Institute of Oncology in Ljubljana between 1972-1992. Data on patient gender, age, disease history, extent of disease, morphological characteristics, mode of therapy and survival were collected. Statistical correlations between possible prognostic factors and survival were analysed by univariate and Cox's multivariate analysis.

The 10-year survival of the 154 patients was 60%. Multivariate analysis showed that tumour differentiation, primary tumour size, vascular invasion, distant metastases, regional lymph-node metastases, histological tumour type and age were independent prognostic factors for survival. The best prognosis was found in patients with well-differentiated T1 or T2 tumours, without extensive vascular invasion, without distant or regional metastases and aged under 46 years. Patients with Hürthle-cell type carcinomas had better prognosis than those with the follicular type. The worst prognosis was found in patients with poorly differentiated T4 tumours, with extensive vascular invasion, with distant or regional metastases and aged over 60 years.