title: Serum thyroglobulin improves the sensitivity of the McGill Thyroid Nodule Score for well-differentiated thyroid cancer.
abstract: BACKGROUND
  The McGill Thyroid Nodule Score (MTNS) is a scoring system devised to help physicians to assess the preoperative risk that a thyroid nodule is malignant. It uses 22 different known risk factors for thyroid cancer (radiation exposure, microcalcifications on ultrasound, positive HBME-1 stain on biopsy, etc.) and attributes a percentage risk that the nodule is malignant. Recently, preoperative thyroglobulin (Tg) levels have been shown to correlate with the risk of malignancy. The aim of this study was to incorporate Tg levels into the already established MTNS.
  
  
  METHODS
  This is a retrospective analysis of 184 thyroidectomy patients at the McGill University Thyroid Cancer Center. Patients with preoperative Tg levels were included in the study, and patients with incidental papillary microcarcinoma without extrathyroidal extent on final pathology were excluded. MTNS scores were calculated for all patients. Preoperative Tg levels of 75 ng/mL added one point to the MTNS, and levels of 187.5 ng/mL added two points. The new system is named MTNS+.
  
  
  RESULTS
  Malignancy rates were calculated for each MTNS+ score. Patients with a score of 0-1 were <5% at risk of malignancy. The malignancy rate for scores of 2-3 was 14.29%, followed by 28.95% for scores of 4-6, 32.65% for scores of 7-8, 64.86% for scores of 9-11, 71.43% for scores of 12-14, 78.57% for scores of 15-18, and 92.31% for scores of 19-22. All patients (five of five) with an MTNS+ score of 23 or more had a malignant final pathology result. Patients with scores greater than eight had a relative risk of 2.5 [CI 1.79-3.49] of malignancy compared to patients with lower scores. MTNS+ showed good specificity at higher scores, with 89%, 96%, and 100% at scores above 11, 14, and 20 respectively. Compared to MTNS, adding Tg levels did not improve positive predictive values (PPV) or specificity, but improved sensitivity by 7.89% for scores greater than eight, and by up to 10.48% for scores greater than seven.
  
  
  CONCLUSIONS
  This study shows that adding Tg to the MTNS increases the sensitivity of this scoring system. Moreover, it suggests that a combined scoring system such as the MTNS+ can accurately stratify the risk of well-differentiated malignancy in patients with thyroid nodules.
authors.affiliation: 1 Department of Otolaryngology-Head and Neck Surgery, McGill University , Jewish General Hospital, Montreal, Canada .
authors.forename: Patrick
authors.initials: P
authors.lastname: Scheffler
authors.forename: Veronique I
authors.initials: VI
authors.lastname: Forest
authors.forename: Rebecca
authors.initials: R
authors.lastname: Leboeuf
authors.forename: Anca V
authors.initials: AV
authors.lastname: Florea
authors.forename: Michael
authors.initials: M
authors.lastname: Tamilia
authors.forename: Noah B
authors.initials: NB
authors.lastname: Sands
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hier
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Mlynarek
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Payne
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood*; D002471:Cell Transformation, Neoplastic; D003937:Diagnosis, Differential; D005260:Female; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011792:Quebec / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D016606:Thyroid Nodule / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D013954:Thyroglobulin