Brock (PanCan) Pulmonary Nodule Malignancy Risk

The Brock (PanCan) model was derived on 7008 nodules from the Pan-Canadian Early Detection of Lung Cancer Study and externally validated on 5021 nodules from British Columbia Cancer Agency screening cohorts, with discrimination above AUC 0.90 even for nodules 10 mm or smaller. Nodule size enters through a nonlinear fractional-polynomial transformation, (size/10)^(−0.5) − 1.58113883, and continuous predictors are centered (age at 62 years, nodule count at 4). The parsimonious models retain only female sex, transformed size and upper-lobe location (plus spiculation in model 1b); the full models add age, family history of lung cancer, CT emphysema, nodule type and nodule count. Coefficients here are transcribed directly from Table 2 of the NEJM 2013 paper. The British Thoracic Society recommends this model for assessing solid nodules ≥8 mm, using a 10% risk threshold to trigger PET-CT evaluation. Perifissural nodules are handled separately: none of the 571 perifissural nodules in the derivation and validation cohorts was malignant.