Nomograms for predicting the prognosis of stage IV colorectal cancer after curative resection: A multicenter retrospective study

Purpose: Although stage IV colorectal cancer (CRC) encompasses a wide variety of clinical conditions with diverse prognoses, no statistical model for predicting the postoperative prognosis of stage IV CRC has been established. Thus, we here aimed to construct a predictive model for disease-free survival (DFS) and overall survival (OS) after curative surgery for stage IV CRC using nomograms. Methods: The study included 1133 stage IV CRC patients who underwent curative surgical resection in 19 institutions. Patients were divided into derivation (n = 586) and validation (n = 547) groups. Nomograms to predict the 1- and 3-year DFS rates and the 3- and 5-year OS rates were constructed using the derivation set. Calibration plots were constructed, and concordance indices (c-indices) were calculated. The predictive utility of the nomogram was validated in the validation set. Results: The postoperative carcinoembryonic antigen (CEA) level, depth of tumor invasion (T factor), lymph node metastasis (N factor), and number of metastatic organs were adopted as variables for the DFS-predicting nomogram, whereas the postoperative CEA level, T factor, N factor, and peritoneal dissemination were adopted for the nomogram to predict OS. The nomograms showed moderate calibration, with c-indices of 0.629 and 0.640 in the derivation set and 0.604 and 0.637 in the validation set for DFS and OS, respectively. Conclusions: The nomograms developed were capable of estimating the probability of DFS and OS on the basis of only 4 variables, and may represent useful tools for postoperative surveillance of stage IV CRC patients in routine practice.