title: Minimally invasive follicular thyroid cancer: treat as a benign or malignant lesion?
abstract: Follicular thyroid cancer is the second most common thyroid cancer, accounting for 10%-15% of all cases. Follicular thyroid carcinomas (FTCs) can be classified into two subtypes: classic (C), which exhibit both vascular and capsular invasion and minimally invasive (MI), which only has limited capsular invasion. Both types, like most well-differentiated thyroid cancers, are traditionally treated the same: a completion thyroidectomy usually followed by radioiodine ablation. We hypothesize that MI-FTC may behave more like a benign follicular adenoma rather than C-FTC and may not require total thyroidectomy and radioiodine.
  
  
  
  A prospective thyroid database was screened for patients with follicular cell tumors. Data on recurrence rates, disease-free survival, and requirement for follow-up surgery and/or radioiodine were compared. Disease-free survival was determined by the Kaplan-Meier method. Analysis of variance and chi-square test were used to evaluate other factors.
  
  
  
  In total, there were 419 benign adenomas (87%), 21 MI-FTCs (4.5%), and 41 C-FTCs (8.5%). Patients with adenomas were younger (P = 0.035) and were more likely to be female (P = 0.001). Importantly, the 16-y disease-free survival was 100% in the adenoma group, 100% in the MI-FTC group, and 36.6% in the C-FTC group (P < 0.0001).
  
  
  
  MI-FTCs behave similar to adenomas with 100% disease-free survival with up to 16 y of follow-up. These data suggest MI-FTCs could be potentially treated by thyroid lobectomy alone like follicular adenomas and perhaps should be classified as a distinct clinical entity.
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors.forename: Aaron
authors.initials: A
authors.lastname: Robinson
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors.forename: David
authors.initials: D
authors.lastname: Schneider
authors.affiliation: Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Sippel
authors.affiliation: Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama. Electronic address: herbchen@uab.edu.
authors.forename: Herbert
authors.initials: H
authors.lastname: Chen
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000473:pathology* / Q000628:therapy; D000236:Adenoma / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D016208:Databases, Factual; D003937:Diagnosis, Differential; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D019275:Radiopharmaceuticals / Q000627:therapeutic use*; D018714:Radiotherapy, Adjuvant; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000628:therapy; D013965:Thyroidectomy; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals
keywords: Thyroid cancer