Follicular and Hurthle cell carcinoma: Predicting outcome and directing therapy

Background. Follicular thyroid cancer is a heterogeneous disease including follicular and Hurthle cell and tumors with and without vascular and major capsular invasion. Analyses of prognosis and risk groups have been criticiz ed for not taking these differences into account. Methods. Retrospective analysis was done of 240 patients treated from 1940 to 1997. Results. Ninety-two patients without vascular or major capsular invasion fo llowed up for a median of 14 years had no recurrences or deaths. In the rem aining 148 patients, 32 had Hurthle cell and 116 had follicular cell carcin oma. Patients with Hurthle cell carcinoma were significantly older (55 vs 4 7 years; P = .0014). Lymphatic metastases did not influence outcome. Patien ts who were at high risk by age and sex, metastases, extent, and size had a 20-year survival rate of 36% for follicular and 35 % for Hurthle cell carc inoma; patients at low risk had 20-year survival rates of 94 % and 89%, res pectively, with no significant difference between follicular and Hurthle ce ll carcinoma. Recurrences were treated successfully in 33% of patients with follicular carcinoma but never cured in patients with Hurthle cell carcino ma. Bilateral versus unilateral operation or radioiodine for ablation did n ot alter outcome. Conclusions. Follicular and Hurthle cell carcinoma with minimal capsular in vasion behaved benignly. Age and sex, metastases, extent, and size risk cri teria differentiate strongly between patients with highrisk and low-risk fo llicular and Hurthle cell carcinoma. Controlling for risk factors, Hurthle cell and follicular cell carcinomas have similar prognoses.