J Gastric Cancer.  2017 Sep;17(3):204-211. 10.5230/jgc.2017.17.e21.

External Validation of a Gastric Cancer Nomogram Derived from a Large-volume Center Using Dataset from a Medium-volume Center

• Kim PS
• Lee KM
• Han DS
• Yoo MW
• Han HS
• Yang HK
• Bang HY

• KMID: 2389824
• DOI: http://doi.org/10.5230/jgc.2017.17.e21

Abstract

PURPOSE
Recently, a nomogram predicting overall survival after gastric resection was developed and externally validated in Korea and Japan. However, this gastric cancer nomogram is derived from large-volume centers, and the applicability of the nomogram in smaller centers must be proven. The purpose of this study is to externally validate the gastric cancer nomogram using a dataset from a medium-volume center in Korea.
MATERIALS AND METHODS
We retrospectively analyzed 610 patients who underwent radical gastrectomy for gastric cancer from August 1, 2005 to December 31, 2011. Age, sex, number of metastatic lymph nodes (LNs), number of examined LNs, depth of invasion, and location of the tumor were investigated as variables for validation of the nomogram. Both discrimination and calibration of the nomogram were evaluated.
RESULTS
The discrimination was evaluated using Harrell's C-index. The Harrell's C-index was 0.83 and the discrimination of the gastric cancer nomogram was appropriate. Regarding calibration, the 95% confidence interval of predicted survival appeared to be on the ideal reference line except in the poorest survival group. However, we observed a tendency for actual survival to be constantly higher than predicted survival in this cohort.
CONCLUSIONS
Although the discrimination power was good, actual survival was slightly higher than that predicted by the nomogram. This phenomenon might be explained by elongated life span in the recent patient cohort due to advances in adjuvant chemotherapy and improved nutritional status. Future gastric cancer nomograms should consider elongated life span with the passage of time.

Keyword

Stomach neoplasms; Survival; Nomograms; Validation studies

MeSH Terms

Calibration
Chemotherapy, Adjuvant
Cohort Studies
Dataset*
Discrimination (Psychology)
Gastrectomy
Humans
Japan
Korea
Lymph Nodes
Nomograms*
Nutritional Status
Retrospective Studies
Stomach Neoplasms*

Figure

• 

  Fig. 1 SNUH gastric cancer nomogram. Figure is adapted from Han et al. [8]. SNUH = Seoul National University Hospital; LN = lymph node.

• 

  Fig. 2 Calibration of SNUH gastric cancer nomogram using KUMC patients' data. The x-axis represents 5-year survival predicted by the nomogram and the y-axis represents actual survival, calculated by the Kaplan-Meier method. The solid line is the baseline on which predicted survival and actual survival match. The dotted line represents the 10% margin of error. SNUH = Seoul National University Hospital; KUMC = Konkuk University Medical Center.

• 

  Fig. 3 The box plot shows the distribution of 5-year overall survival predicted by the nomogram in each group of TNM classification. TNM = tumor, node, and metastasis.

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