Overall survival in patients over 40 years old with surgically resected pancreatic carcinoma: a SEER-based nomogram analysis

Abstract

Background: The aim of this study was to identify the determinants of overall survival (OS) within patients over 40 years old with surgically resected pancreatic carcinoma (PC), and to develop a nomogram with the intention of OS predicting.

Methods: A total of 6341 patients of 40 years of age or later with surgically resected PC between 2010 and 2015 were enrolled from the Surveillance, Epidemiology, and End Results (SEER) program and randomly assigned into training set (4242 cases) and validation set (2099 cases). A nomogram was constructed for predicting 1-, 2- and 3-years OS based on univairate and multivariate Cox regression. The C-index and calibration plot were adopted to assess the nomogram performance.

Results: Our analysis showed that age, location of carcinoma in pancreas, tumor grade, TNM stage, size of carcinoma together with lymph node ratio (LNR) were considered to be independent overall survival predictors. A nomogram based on these six factors was developed with C-index being 0.680 (95%CI: 0.667-0.693). All calibration curves of OS fitted well. The OS curves stratified by nomogram-predicted probability score (≥20, 10-19 and < 10) demonstrated statistically significant difference not only within training set but also in validation set.

Conclusions: The present nomogram for OS predicting can serve as the efficacious survival-predicting model and assist in accurate decision-making for patients over 40 years old with surgically resected PC.

Keywords: Nomogram; Overall survival; Pancreatic carcinoma; Prognosis.

Fig. 1

Kaplan-Meier OS curves stratified by patient characteristics: (a)Age; (b) Pancreatic Location; (c) Tumor Grade; (d) TNM 7th stage; (e) Tumor Size; (F)LNR. Abbreviations: TNM Tumor-Node-Metastasis, LNR lymph node ratio

Fig. 2

Nomogram for predicting 1-, 2-, 3-years OS of patients The nomogram is used by adding the points identified on the scale for 6 variables to achieve the total points, and a vertical line is drawn downward to the survival axes to determine the probability of 1-,2- and 3-years OS. Abbreviations: TNM Tumor-Node-Metastasis, LNR lymph node ratio, OS overall survival.

Fig. 3

Calibration plots of nomogram for 1-, 2- and 3-year OS prediction of the training set (a, b, c) and validation set (d, e, f) X-axis represents the nomogram-predicted OS probability and Y-axis represents the actually observed OS probability. The diagonal line indicates the perfect nomogram reference. Dots with bars represent nomogram-predicted probabilities together with 95% confidence interval.

Fig. 4

Kaplan-Meier OS curves according to the risk levels of nomogram-predicted survival probabilities: (a) Training set; (b) Validation set