Survival nomograms for stage III colorectal cancer

Abstract

The postoperative survival of patients with stage III colorectal cancer (CRC) various obviously. We sought to develop novel nomograms for predicting the survival of these patients after radical surgery and postoperative chemotherapy.A total of 620 consecutive patients with stage III CRC who underwent curative resection and postoperative chemotherapy between January 2009 and December 2015 were retrospectively collected and randomly allocated to the training (n = 372) or validation cohort (n = 248). Clinicopathological factors were collected and analyzed. On the basis of data from 372 patients in the training set, predictive factors for overall survival (OS) and disease-free survival (DFS) were identified using multivariate Cox regression and used to construct nomograms. The predictive performance of the nomograms was assessed by concordance index (C-index) and calibration plots. An external cohort of 248 patients was used to validate the nomograms. Furthermore, nomogram performance was compared with the performance of T and N stage stratification.Tumor differentiation grade, lymph node metastasis ratio, intravascular emboli (IVE), preoperative serum carcinoembryonic antigen (CEA) level, albumin to globulin ratio (AGR), T stage and N stage were significant prognostic factors for OS on multivariate analysis; whereas, Tumor differentiation grade, lymph node metastasis ratio, IVE, AGR and N stage were significant for DFS. Nomograms to predict 3- and 5-year OS and DFS were established that performed well (C-indexes of 0.734 [95% CI, 0.691-0.779] for OS and 0.699 [95% CI, 0.657-0.740] for DFS prediction), and nomogram accuracy was confirmed in the validation cohort. Furthermore, model comparison proved that the nomograms were superior to risk stratification by T and N stage for stage III CRC.We propose 2 practical nomograms for stage III CRC patients that provide more accurate prognostic predictions and should be helpful for guiding individualized treatment and postoperative surveillance.

Figure 1

Multivariate analysis of the training set. Forest plots show multivariate survival analyses of OS (A) and DFS (B). DFS = disease-free survival, OS = overall survival.

Figure 2

Stage III and IV colorectal cancer survival nomogram. Nomograms for predicting OS (A) and DFS (B) based on the training set. Each variable corresponds to a point on’ the scale. According to the sum of these points projected on the bottom scales, the nomogram can provide the probabilities of 3- and 5-year OS and DFS for an individual patient. DFS = disease-free survival, OS = overall survival.

Figure 3

The internal calibration curve for predicting patient survival. Internal calibration nomogram for 3-year and 5-year OS (A, B) and 3-year and 5-year DFS (C, D). The 45-degree line represents an ideal match between the actual survival (Y-axis) and nomogram-predicted survival (X-axis). The perpendicular line means 95% confidence intervals. DFS = disease-free survival, OS = overall survival.

Figure 4

The external calibration curve for predicting patient survival. External calibration nomogram for 3-year and 5-year OS (A, B) and 3-year and 5-year DFS (C, D). The 45-degree line represents an ideal match between the actual survival (Y-axis) and nomogram-predicted survival (X-axis). The perpendicular line means 95% confidence intervals. DFS = disease-free survival, OS = overall survival.

Figure 5

Kaplan–Meier curve analysis of prognostic stratification and predictive capability comparison. Prognostic classification of OS and DFS using the T staging (P <.001) (A and B); Prognostic stratification of OS and DFS using the N staging (P <.001) (C and D); Comparing the performance of model with T or N staging in predicting OS (E); Comparing the performance of model with T or N staging in predicting DFS (F). DFS = disease-free survival, OS = overall survival.