Background. Follicular carcinomas of the thyroid are less common than
papillary carcinomas of the thyroid, and the available data on prognos
tic factors are relatively scant. A retrospective study covering four
decades was undertaken to evaluate clinical and pathologic findings wi
th regard to their effect on prognosis. Methods. In 195 cases of folli
cular carcinoma treated from 1954 to 1991 age, sex, histologic type (m
inimally invasive vs. widely invasive), tumor size, and local, regiona
l, and distant spread as well as the contribution of treatment to surv
ival were evaluated in relation to prognosis. Results. Age was a signi
ficant prognostic factor: there was 100% survival of patients younger
than 20 years of age at diagnosis and only one death in the 20-39 year
age group. Sex was not a significant prognostic factor, although ther
e was a tendency to a better prognosis in females. Tumor size was sign
ificant, more than 6 cm having a poor prognosis. Blood vessel invasion
influenced prognosis for the first 10 years. The presence of distant
metastases was significant regarding survival. Lymph node involvement
had a negative effect on the outcome. Conclusions. The factors of age,
tumor size, invasion of blood vessels, and distant metastases are sig
nificant predictors of survival for patients with follicular carcinoma
, whereas sex is not; regional spread needs to be evaluated further.