Nomogram predicted survival of patients with adenocarcinoma of esophagogastric junction

Abstract

Background: The aim of this study is to develop a prognostic nomogram for patients with adenocarcinoma of esophagogastric junction and compare its predictive accuracy with the traditional tumor-node-metastasis (TNM) malignant staging system.

Methods: Patients from the Surveillance, Epidemiology, and End Results Program (from 1988 to 2011) and the First Affiliated Hospital of Xi'an Jiaotong University (from 2005 to 2010) were collected retrospectively. Preselected multiple potential interactions were tested irrespective of significance as nomogram parameters. And the Harrell's C-index was used to estimate the accuracy of the nomogram system. Model validation was performed using bootstrap to quantify our modeling strategy.

Results: In our study, six clinical associated factors (age, sex, depth of invasion, metastasized lymph nodes, examined lymph nodes, histological grade) were evaluated in the nomogram. In the training set, the nomogram exhibited superior discrimination power compared with the American Joint Committee on Cancer (AJCC) TNM classification (Harrell's C-index, 0.69 and 0.63, respectively). Calibration of the nomogram predicted survival was similar to the actual overall survival. In the validation set, the discrimination of nomogram was also better than the AJCC TNM staging system (C-index, 0.75 and 0.65, respectively), and the calibration of nomogram predicted survival was within a 10 % margin of actual overall survival.

Conclusions: Based on the patients with adenocarcinoma of esophagogastric junction from a Western and an Eastern database, the nomogram provided significantly improved discrimination than the traditional AJCC TNM classification and also provided an accurate individualized prediction of the survival.

Fig. 1

Transformation of continuous variables in univariate analysis using restricted cubic splines

Fig. 2

Nomogram predicted 1- to 5-year overall survival using six available clinical characteristics. To use the nomogram to calculate personal predicted survival, the patient’s age was located on the row labeled Age (year) and a straight line was drawn up to the row labeled Points to determine the corresponding points. This process was repeated for each of the remaining factors by drawing a straight line to the “Points” row to determine the points associated with each factor. After summarizing the total points, one located the appropriate total point number and drawn a straight line from this to the rows labeled 1-year survival, 2-year survival, 3-year survival, 4-year survival, and 5-year survival to determine the patient’s predicted survival probability

Fig. 3

Kaplan-Meier survival curves of AJCC TNM stages and nomogram trisection stages of non-metastasis patients with AEG

Fig. 4

Calibration of the nomogram in the training set. Nomogram predicted probability of overall survival was plotted on the x-axis, actual overall survival was plotted on the y-axis and 95 % CIs measured by Kaplan-Meier analysis. All predictions lie within the 10 % margin of error (within the blue dots line). a Three-year survival. b Five-year survival

Fig. 5

Calibration of the nomogram in the validation set. Nomogram predicted probability of overall survival was plotted on the x-axis, actual overall survival was plotted on the y-axis and 95 % CIs measured by Kaplan-Meier analysis. All predictions lie within the 10 % margin of error (within the blue dots line). a Three-year survival. b Five-year survival

Fig. 6

Predicted 5-year overall survival probability by AJCC TNM stage. A wide range of predicted survival could be identified in each TNM stage

Fig. 7

The distribution of the number of examined lymph nodes in different AJCC stages and nomogram stages