title: The McGill Thyroid Nodule Score's (MTNS+) role in the investigation of thyroid nodules with benign ultrasound guided fine needle aspiration biopsies: a retrospective review.
abstract: BACKGROUND
  Ultrasound guided fine needle aspiration (USFNA) biopsies of thyroid nodules sometimes create a decision-making dilemma for surgeons as they may yield falsely benign results. The McGill Thyroid Nodule Score + (MTNS+) was developed to aid in clinical guidance regarding the management of patients with these USFNA results. The aim of this study was to assess the MTNS+ as a clinical tool in patients with benign preoperative thyroid nodule USFNAs and to analyze the relationship between nodule size and malignancy in these patients.
  
  
  METHODS
  We conducted a retrospective chart review of 1312 patients who underwent thyroidectomies between 2010 and 2015 at the McGill University Teaching Hospitals. Patients with Bethesda II (benign) USFNA results, calculated MTNS+, and nodule size evaluated on ultrasound were included in the study. The false-negative rate was calculated, and MTNS+ and nodule size were each compared to final pathology results. Binary logistic regression was used for statistical analysis.
  
  
  RESULTS
  Of the 1312 patients, 101 met the inclusion criteria and together had an average MTNS+ score of 6.83, which corresponds to a predicted malignancy rate between 25 and 33 %. Final pathology revealed malignancy in 16 (15.8 %) subjects. The average MTNS+ of patients with malignant nodules on surgical pathology was 8.25, while that of patients with benign nodules was 6.56. Patients with nodule size 1-1.9 cm (a) and 2-2.9 cm (b) each had an equal rate of malignancy of 2.97 % (n = 3), nodule size 3-3.9 cm (c) had a rate of 1.98 % (n = 2), and nodule size ≥4 cm (d) a rate of 7.92 % (n = 8).
  
  
  CONCLUSIONS
  The rate of malignancy (15.8 %) is higher than expected when reviewing the risk of malignancy in nodules considered as Bethesda class 2. On the other hand, the rate is lower than the 25-33 % predicted by the MTNS+. We also found a higher malignancy rate for nodules above 4 cm in size, but size was a poor predictor of malignancy when used alone. Therefore, while the MTNS+ may be helpful at helping to identify USFNAs that are incorrectly classified as benign, the percentage risk of malignancy is lower than expected.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, McGill University Health Centre, 1001 Boulevard Decarie, Montreal, QC, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Khalife
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, McGill University Health Centre, 1001 Boulevard Decarie, Montreal, QC, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bouhabel
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Road, Montreal, QC, Canada.
authors.forename: Veronique-Isabelle
authors.initials: VI
authors.lastname: Forest
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Road, Montreal, QC, Canada.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hier
authors.affiliation: Department of Pathology, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Road, Montreal, QC, Canada.
authors.forename: Louise
authors.initials: L
authors.lastname: Rochon
authors.affiliation: Department of Endocrinology and Metabolism, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Road, Montreal, QC, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Tamilia
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, McGill University Health Centre, 1001 Boulevard Decarie, Montreal, QC, Canada. rkpayne@sympatico.ca.|Department of Otolaryngology-Head and Neck Surgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Road, Montreal, QC, Canada. rkpayne@sympatico.ca.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Payne
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012737:Sex Factors; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery; D016606:Thyroid Nodule / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D018084:Ultrasonography, Interventional
keywords: Benign nodule; Bethesda II; McGill Thyroid Nodule Score; Nodule size; Thyroid cancer; Ultrasound-guided fine needle aspiration biopsy