Prognostic nomogram for disease-specific survival of carcinoma ex pleomorphic adenoma of the salivary gland

Background: The purpose of this study was to establish an effective prognostic nomogram for carcinoma ex pleomorphic adenoma (Ca-ex-PA) of the salivary gland. Methods: The nomogram was based on a retrospective study on 223 patients who underwent surgical operation for Ca-ex-PA from 2001 to 2010. The predictive accuracy and discriminative ability of the nomogram were determined by concordance index (C-index) and calibration curve. The results were validated using bootstrap resampling and a prospective study on 111 patients operated on from 2011 to 2012. Results: On multivariate analysis of the primary cohort, independent factors for disease-specific survival (DSS) were age, tumor diameter, degree of capsule invasion, lymph node metastasis, and the interaction between tumor site and histological subtype, which were all selected into the nomogram. The C-index of the nomogram for predicting DSS was 0.90 and 0.86 in the primary cohort and validation cohort, respectively. Conclusion: The proposed nomogram resulted in more accurate prognostic predictions for patients with Ca-ex-PA.