Multivariate analysis of histopathological features as prognostic factors in patients with papillary thyroid carcinoma.

A retrospective analysis of 121 papillary thyroid carcinomas was made to assess prognostic factors including histological variants which might be related to survival. The mean follow-up period was 10 years and clinical, surgical and histopathological data were studied. The survival curves were analysed by the Kaplan-Meier method and the multivariate analysis used Cox's regression model. Eighty-seven patients had well differentiated papillary cancers. The survival rate for papillary thyroid cancer was 86 per cent at 5 years and 72 per cent at 10 years. Factors showing prognostic significance for survival were tumour size, extrathyroid extension and histological type. Disease-free survival was influenced by sex, existence of a capsule and nodal metastases. Factors showing a favourable prognosis were: age under 45 years, size less than 4 cm, no extrathyroid extension and well differentiated histological type (P < 0.001). Histological subtype was one of the most important prognostic factors.