Papillary thyroid carcinoma - Prognostic index for survival including the histological variety

Background: Numerous prognostic factors have been studied for survival in p atients with papillary thyroid carcinoma (PTC), although there are few mult ivariate studies that include the histological variety of PTC. Hypothesis: There are prognostic factors that influence survival in a serie s of patients with PTC, including the histological variety, and a new progn ostic index (PI) for survival can be formulated by accounting for these fac tors. Design: A retrospective study. Setting: A university hospital department of surgery. Patients: Between January 1970 and December 1995, 200 patients undergoing s urgery for PTC were observed (mean follow-up, 8 years). Main Outcome Measures: A univariate analysis was done for survival rates us ing the Kaplan-Meier estimation method. The possible prognostic factors wer e evaluated using a multivariate analysis according to the Cox model. We fo rmulated a PI and defined 3 risk groups (low, medium, and high) for mortali ty. Results: Of the 200 patients, 175 (87.5%) are still alive. Of the 25 deaths , 19 (9.5%) were due to the tumor. The survival was 97.5% at 1 year, 92.8% at 5, 89.5% at 10, and 83.9% at 15 and 20 years. The prognostic factors obt ained after the multivariate analysis were age, tumor size, extrathyroid sp read, and histological variant of the PTC. The PI is calculated as follows: PI = (2 X size) + (6 X spread) + (2 X variant) + (3 X age). As for the ris k groups, the low-risk group showed a mortality of 0%; the medium-risk grou p, 17.1%; and the high-risk group, 76.5%. Conclusions: The histological variety of PTC has prognostic value for survi val in patients with PTC. As risk factors for PTC mortality, we consider an age of 50 years or older, a tumor larger than 4 cm, the existence of extra thyroid spread, and a certain histological subtype of PTC. With these risk factors, it is possible to formulate a PI and classify patients into low-, medium-, and high-risk groups for mortality.