A computed tomography-based nomogram for preoperative prediction of synchronous peritoneal carcinomatosis in colorectal cancer.

Abstract

14 Background: Peritoneal carcinomatosis (PC) of colorectal cancer remain poor and is considered to be the terminal stage. Early detection of PC can bring survival benefit for chances of complete cytoreductive surgery. In this study, we have developed and validated a CT-based nomogram for preoperative prediction of synchronous PC in CRC. Methods: The CT-based nomogram optimized for image classification of PC was developed and validated in a large cohort. The specific features of synchronous PC were extracted from preoperative CT arterial stage scans by radiologists. A CT-based model was constructed by Boruta algorithm and multivariate logistic regression in the training set and validated in the test set. A CT-based nomogram was then built to predict the risk value of PC. The performance and efficacy of this nomogram to discriminate PC were assessed. Results: A total of 170 eligible CRC patients with synchronous PC were randomly divided into a training set (n = 92) and a validation set (n = 78). After processing and partition, five items of PC-related features including tumor location, cT stage, distant metastasis, thickened greater omentum and pelvic nodules were enrolled into this CT-based model. In the training set, the ROC shows AUC of CT-based model was 0.929(95% CI: 0.764-0.946). The sensitivity was 73.2% and the specificity was 98.3%. The positive predictive value (PPV) was 82.26%, while the negative predictive value (NPV) was 100%. In the test set, AUC by the ROC was 0.855(95% CI: 0.764-0.946). The sensitivity of CT-based model was 72.7% and the specificity was 93.3%. The PPV was 82.35%, while the NPV was 88.89%. These results show high predicted accuracy of CT-based model in diagnosis of synchronous PC both in the training set and test set. A nomogram based on these five preoperative predictors of PC was created. This CT-based nomogram showed good diagnostic performance by calibration curve. The decision curves analysis revealed high benefit of this CT-based nomogram in clinical decision. Conclusions: The CT-based nomogram has shown great potential in the detection and diagnosis of synchronous peritoneal metastasis in colorectal cancer.