Multifactorial study of prognostic factors in differentiated thyroid carcinoma

Using survival corrected for intercurrent deaths as an endpoint, the prognostic significance of age, sex, histology, clinical extent of disease, size of primary tumor, type and result of treatment, was assessed in a series of 133 patients with differentiated thyroid carcinomas treated over a 16-year period. The following parameters were shown to be unfavourably related to survival: old age, follicular moderately-differentiated histological type, extrathyroid growth of the primary tumor and/or presence of distant metastases at diagnosis. In patients not cured after surgery, postoperative radioiodine therapy was correlated with, better survival rates. A multivariate statistical analysis (Cox model) showed that tumor stage and age at diagnosis were the major determinants of prognosis. Based on this data a risk index was worked out and three low/intermediate/high risk subgroups, characterized by significantly different survival rates, were identified in the study population.