Follicular thyroid carcinoma: differences in clinical relevance between minimally invasive and widely invasive tumors

BACKGROUND: Evidence on the biological behavior and clinical courses of minimally invasive and widely invasive follicular thyroid carcinoma (MI-FTC, WI-FTC) is still debatable. The current study was conducted to identify differences between MI and WI tumors and those prognostic parameters influencing late outcome such as local recurrence and survival. METHODS: From January 1998 to October 2013, 71 patients were operated on in our department because of a FTC. A retrospective cohort study was carried out to compare 42 MI-FTC and 29 WI-FTC. The comparison involved evaluation of patient characteristics, tumor characteristics, tumor staging, and risk assessment. RESULTS: A diameter greater than 4.0 cm, the presence of vascular invasion, the TNM stage III–IVA, and the high risk at AMES system risk stratification were independent factors significantly related to the presence of a WI-FTC. The only independent predictor of recurrence and disease-free survival at 10-year follow-up was a tumor size greater than 4.0 cm. CONCLUSIONS: More attention must be paid in the postoperative tumor re-staging of those patients with tumor size larger than 4.0 cm, which was the only parameter predicting recurrence and influencing disease-free survival. Nevertheless, definitive recommendations cannot be made without a longer follow-up.