Prognostic factors and risk group analysis in follicular carcinoma of the thyroid.

BACKGROUND The understanding of prognostic factors has facilitated stratification of risk groups in differentiated carcinoma of the thyroid. The prognostic factors have clearly identified the risk groups as low, intermediate, and high risk. Risk group categorization has facilitated a selective surgical approach for thyroid carcinoma. METHODS A retrospective review of 228 patients with follicular carcinoma of the thyroid was undertaken. Various prognostic factors and risk groups were analyzed. Univariate and multivariate analyses were performed, and the survival curves were plotted by the Kaplan-Meier method. Fifty-nine (26%) patients presented with Hürthle cell histology. The risk groups revealed 62 patients in the low, 84 in the intermediate, and 82 in the high risk groups. RESULTS The 10-year survival for low, intermediate, and high risk groups was 98%, 88%, and 56%, respectively, and the 20-year survival for the same groups was 97%, 87%, and 49%, respectively. Adverse prognostic factors included age older than 45 years (p < 0.001), Hürthle cell variety (p = 0.05), extrathyroidal extension, tumor size exceeding 4 cm, and the presence or absence of distant metastasis (p < 0.001). Gender, focality, and presence of lymph node metastasis had no significant impact on prognosis. CONCLUSIONS Patients in the low risk group have excellent survival, whereas the high risk group behaves poorly. Appropriate selection of treatment for the primary disease and adjuvant therapy should be considered on the basis of the prognostic factors and risk group analysis.