An imaging-based approach predicts clinical outcomes in prostate cancer through a novel support vector machine classification

// Yu-Dong Zhang 1 , Jing Wang 2 , Chen-Jiang Wu 1 , Mei-Ling Bao 3 , Hai Li 3 , Xiao-Ning Wang 1 , Jun Tao 4 and Hai-Bin Shi 1 1 Department of Radiology, the First Affiliated Hospital with Nanjing Medical University, Nanjing, China 2 Center for Medical Device Evaluation, CFDA, Beijing, China 3 Department of Pathology, the First Affiliated Hospital with Nanjing Medical University, Nanjing, China 4 Department of Urology, the First Affiliated Hospital with Nanjing Medical University, Nanjing, China Correspondence to: Hai-Bin Shi, email: // Keywords : prostate cancer; biochemical recurrence; MRI; radical prostatectomy; support vector machine Received : April 27, 2016 Accepted : August 11, 2016 Published : August 15, 2016 Abstract Preoperatively predict the probability of Prostate cancer (PCa) biochemical recurrence (BCR) is of definite clinical relevance. The purpose of this study was to develop an imaging-based approach in the prediction of 3-years BCR through a novel support vector machine (SVM) classification. We collected clinicopathologic and MR imaging datasets in 205 patients pathologically confirmed PCa after radical prostatectomy. Univariable and multivariable analyses were used to assess the association between MR findings and 3-years BCR, and modeled the imaging variables and follow-up data to predict 3-year PCa BCR using SVM analysis. The performance of SVM was compared with conventional Logistic regression (LR) and D'Amico risk stratification scheme by area under the receiver operating characteristic curve (Az) analysis. We found that SVM had significantly higher Az (0.959 vs. 0.886; p = 0.007), sensitivity (93.3% vs. 83.3%; p = 0.025), specificity (91.7% vs. 77.2%; p = 0.009) and accuracy (92.2% vs. 79.0%; p = 0.006) than LR analysis. Performance of popularized D'Amico scheme was effectively improved by adding MRI-derived variables (Az: 0.970 vs. 0.859, p < 0.001; sensitivity: 91.7% vs. 86.7%, p = 0.031; specificity: 94.5% vs. 78.6%, p = 0.001; and accuracy: 93.7% vs. 81.0%, p = 0.007). Additionally, beside pathological Gleason score (hazard ratio [HR] = 1.560, p = 0.008), surgical-T3b (HR = 4.525, p < 0.001) and positive surgical margin (HR = 1.314, p = 0.007), apparent diffusion coefficient (HR = 0.149, p = 0.035) was the only independent imaging predictor of time to PSA failure. Therefore, We concluded that imaging-based approach using SVM was superior to LR analysis in predicting PCa outcome. Adding MR variables improved the performance of D'Amico scheme.