[Establishment of a prognostic nomogram to predict long-term survival in non-metastatic colorectal cancer patients].

OBJECTIVE

To establish a nomogram to predict long-term survival in non-metastatic colorectal cancer patients.

METHODS

A retrospective analysis was conducted in patients with non-metastatic colorectal cancer who underwent radical surgery in the Department of Colorectal Surgery of Affiliated Union Hospital of Fujian Medical University between January 2000 and December 2014. Univariate and multivariate analyses on disease-free survival (DFS) were performed using the Cox proportional regression model. Based on the multivariate analysis results, a prognostic nomogram was formulated to predict the probability for DFS. Concordance index was applied in predictive evaluation of the nomogram and calibration curves were drawn to test the nomogram's prediction and actual observation of the 5-year DFS rate. The predictive ability of nomogram was compared with AJCC-7 staging system.

RESULTS

A total of 2 641 patients were identified. The median age was 59.3 years old, and 60.3% of cases were men. The number of patients with TNM stage 0, I(, II( and III( was 96, 505, 923 and 1043, respectively. The most common tumor site was the rectum, accounting for 43.2%. A total of 413 (15.6%) patients underwent neoadjuvant treatment. The most common gross type of tumor was ulcerative type, accounting for 79.5%. The 3- and 5-year DFS rate was 85.8% and 79.8%, respectively. Based on the Cox proportional regression model, the following six factors were independently associated with reduced DFS rate and were selected for the nomogram: older age, higher pathologic T stage, higher pathologic N stage, higher preoperative serum CEA level, infiltrative gross type and perineural invasion. The results of the nomogram showed that the score of T0, T1, T2, T3 and T4 stage was 0, 2.2, 3.9, 4.1 and 6, respectively, and the score of N0, N1 and N2 was 0, 3.8 and 9.3, respectively. For gross type, the score of expanding type, ulcerative type and infiltrative type was 6, 9 and 10, respectively. The score of perineural invasion was 5.2. Higher scores were added to older age and higher CEA level. The total scores were calculated by taking the sum of the points from all predictors. Higher total score was associated with poor DFS. The prognostic nomogram differentiated well and showed a concordance index of 0.718, which was better than AJCC-7 staging system (concordance index=0.683). Also, the calibration of nomogram predictions was good.

CONCLUSIONS

A nomogram based on 6 independently prognostic factors to predict long-term survival in non-metastatic colorectal cancer patients is established successfully. The nomogram can be conveniently used to facilitate the accurate individualized prediction of DFS rates in patients with non-metastatic colorectal cancer.