Prognostic factors in follicular carcinoma of the thyroid: a study of 198 cases.

Abstract

Prognostic parameters for papillary carcinoma of the thyroid have been defined by several groups. However, no such study has been reported for follicular carcinoma. We undertook a retrospective study of well-differentiated carcinoma of the thyroid operated at the Tata Memorial Hospital during the period 1970-1985. In our series, follicular carcinoma formed 48% of the well-differentiated carcinomas of the thyroid. The variables age, sex, size, extrathyroidal spread, distant metastases, and lymph node metastases were evaluated. The survival was plotted according to the Kaplan-Meier method, and graphs compared by log-rank test. Univariate and multivariate analyses were performed. Based on our experience we stratified the cases into low-risk and high-risk groups. The low-risk group included: age below 40 years, tumor size less than 5 cm. and no extrathyroidal extension or metastases. This low risk group had 100% survival at 15 years, compared with 40% survival for the high-risk group (P <.001). Seventy-three percent (73%) of our cases were in the high-risk group. Based on our findings that the majority of our patients were in the high-risk group, we advocate a total or near-total thyroidectomy in treatment of follicular carcinoma of the thyroid. There is a need to arrive at a universally acceptable classification of risk groups in follicular carcinoma of the thyroid gland.