McGill Thyroid Nodule Score (MTNS): "rating the risk," a novel predictive scheme for cancer risk determination.

Objective: There are presently a great number of publications pertaining to the clinical risk factors associated with thyroid cancer. These studies deal mostly with a single feature from either patient demographics, physical examination, laboratory values, imaging, or cytology. We sought to create a novel scoring system that integrates the diagnostic indices of each of these clinical features for carcinoma.

Methods: A retrospective analysis of 1047 consecutive thyroidectomy patients was performed. Each patient was assigned a cancer risk score according to a newly devised 22-variable scoring scheme termed the McGill Thyroid Nodule Score (MTNS). The MTNS was developed by a multidisciplinary team of endocrinologists, thyroid surgeons, and pathologists using already established evidence-based risk factors for thyroid cancer.

Results: The exact incidence of malignancy was calculated for each MTNS score based on final pathology. The incidence for scores of 1 to 3 was 27%, of 4 to 7 was 32%, of 8 was 39%, of 9 to 11 was 63%, of 12 to 13 was 88%, and of 14 to 18 was 93%. All (130 of 130) patients with a score ≥ 19 had carcinoma. A score ≤ 8 correlated with a 32% (115 of 357) risk of thyroid cancer, whereas a score > 8 implied an 86% (417 of 487) risk.

Conclusion: Our data suggest that a combined scoring system, the MTNS, can serve as an accurate predictor of the risk for thyroid cancer in a specific thyroid nodule. This will help physicians better formulate management decisions accordingly.