A novel nomogram based on cardia invasion and chemotherapy to predict postoperative overall survival of gastric cancer patients

Abstract

Background: We aimed to establish and externally validate a nomogram to predict the 3- and 5-year overall survival (OS) of gastric cancer (GC) patients after surgical resection.

Methods: A total of 6543 patients diagnosed with primary GC during 2004-2016 were collected from the Surveillance, Epidemiology, and End Results (SEER) database. We grouped patients diagnosed during 2004-2012 into a training set (n = 4528) and those diagnosed during 2013-2016 into an external validation set (n = 2015). A nomogram was constructed after univariate and multivariate analysis. Performance was evaluated by Harrell's C-index, area under the receiver operating characteristic curve (AUC), decision curve analysis (DCA), and calibration plot.

Results: The multivariate analysis identified age, race, location, tumor size, T stage, N stage, M stage, and chemotherapy as independent prognostic factors. In multivariate analysis, the hazard ratio (HR) of non-cardia invasion was 0.762 (P < 0.001) and that of chemotherapy was 0.556 (P < 0.001). Our nomogram was found to exhibit excellent discrimination: in the training set, Harrell's C-index was superior to that of the 8th American Joint Committee on Cancer (AJCC) TNM classification (0.736 vs 0.699, P < 0.001); the C-index was also better in the validation set (0.748 vs 0.707, P < 0.001). The AUCs for 3- and 5-year OS were 0.806 and 0.815 in the training set and 0.775 and 0.783 in the validation set, respectively. The DCA and calibration plot of the model also shows good performance.

Conclusions: We established a well-designed nomogram to accurately predict the OS of primary GC patients after surgical resection. We also further confirmed the prognostic value of cardia invasion and chemotherapy in predicting the survival rate of GC patients.

Keywords: Gastric cancer; Nomogram; Overall survival; SEER.

Fig. 1

Enrollment flow chart of patient with primary GC after surgical resection according to inclusion and exclusion criteria. GC, gastric cancer; SEER, Surveillance, Epidemiology and End Results; LN, lymph node; TNM, tumor-node-metastasis

Fig. 2

Kaplan-Meier survival curves of the independent prognostic factors (A–E, G–I) and TNM classification (F). The horizontal dotted line indicates the median survival time (OS = 0.5); the vertical line indicates the time at 3 and 5 years. AJCC, American Joint Committee on Cancer

Fig. 3

Kaplan-Meier survival curves of chemotherapy (A) and chemotherapy after adjustment (B)

Fig. 4

Nomogram predicting 3- and 5-year OS after surgical resection of GC. OS, overall survival; GC, gastric cancer; Other, American Indian/AK Native and Asian/Pacific Islander; Well, well differentiated; Moderately, moderately differentiated; Poorly, poorly differentiated and undifferentiated/anaplastic

Fig. 5

Receiver operating characteristic (ROC) curves predicting OS. A 3-year in the training set, B 5-year in the training set, C 3-year in the validation set, and D 5-year in the validation set. OS, overall survival; AUC, area under the receiver operating characteristic curve

Fig. 6

Decision curve analysis (DCA) to evaluate our nomogram and AJCC TNM classification. A 3-year and B 5-year in the training set; C 3-year and D 5-year in the validation set. Horizontal black line: no patients will die; inclined gray line: all patients will die. AJCC, American Joint Committee on Cancer; TNM, tumor-node-metastasis

Fig. 7

Calibration curves predicting overall survival. A 3-year in the training set, B 5-year in the training set, and C 3-year in the validation set. The x-axis represents nomogram-predicted survival; the y-axis represents actual survival and 95% confidence intervals (CIs) measured by Kaplan-Meier analysis