Development and validation of a nomogram for predicting cancer-specific survival in small-bowel adenocarcinoma patients using the SEER database

Abstract

Background: Small bowel adenocarcinoma (SBA) is a rare gastrointestinal malignancy forwhich survival is hampered by late diagnosis, complex responses to treatment, and poor prognosis. Accurate prognostic tools are crucial for optimizing treatment strategies and improving patient outcomes. This study aimed to develop and validate a nomogram based on the Surveillance, Epidemiology, and End Results (SEER) database to predict cancer-specific survival (CSS) in patients with SBA and compare it to traditional American Joint Committee on Cancer (AJCC) staging.

Methods: We analyzed data from 2,064 patients diagnosed with SBA between 2010 and 2020 from the SEER database. Patients were randomly assigned to training and validation cohorts (7:3 ratio). Kaplan‒Meier survival analysis, Cox multivariate regression, and nomograms were constructed for analysis of 3-year and 5-year CSS. The performance of the nomograms was evaluated using Harrell's concordance index (C-index), the area under the receiver operating characteristic (ROC) curve, calibration curves, decision curve analysis (DCA), net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

Results: Multivariate Cox regression identified sex, age at diagnosis, marital status, tumor site, pathological grade, T stage, N stage, M stage, surgery, retrieval of regional lymph nodes (RORLN), and chemotherapy as independent covariates associated with CSS. In both the training and validation cohorts, the developed nomograms demonstrated superior performance to that of the AJCC staging system, with C-indices of 0.764 and 0.759, respectively. The area under the curve (AUC) values obtained by ROC analysis for 3-year and 5-year CSS prediction significantly surpassed those of the AJCC model. The nomograms were validated using calibration and decision curves, confirming their clinical utility and superior predictive accuracy. The NRI and IDI indicated the enhanced predictive capability of the nomogram model.

Conclusion: The SEER-based nomogram offers a significantly superior ability to predict CSS in SBA patients, supporting its potential application in clinical decision-making and personalized approaches to managing SBA to improve survival outcomes.

Keywords: Cancer-specific survival; Neoplasm staging; Nomogram; SEER database; Small bowel adenocarcinoma.

Fig. 1

Flow chart for the selection of eligible patients with adenocarcinoma of the small bowel

Fig. 2

Effect of variables on CSS in patients with adenocarcinoma of the small bowel. (A) Tumor site; (B) Retrieval of regional lymph nodes

Fig. 3

Nomogram for predicting the 3- and 5-year CSS of patients with SBA

Fig. 4

Comparison of the ROC curve of the nomogram for the prediction of CSS in the training group (A: 3 years; B: 5 years) and the validation group (C: 3 years; D: 5 years)

Fig. 5

The calibration of the nomograms using the training group and validation group. (A) 3-year CSS and (B) 5-year CSS according to the training group. (C) 3-year CSS and (D) 5-year CSS according to the training group

Fig. 6

The DCA of the nomograms using the training group and validation group. (A) 3-year CSS and (B) 5-year CSS according to the training group. (C) 3-year CSS and (D) 5-year CSS according to the training group

Fig. 7

X-tile analysis was used to determine the optimal threshold for the total score for categorizing patients with adenocarcinoma of the small bowel into three risk subgroups. (A) Selection points for optimal cutoff values. (B) Histograms of the risk subgroups and the corresponding total scores. (C) Kaplan‒Meier overall survival curves for the three risk subgroups

Fig. 8

Kaplan‒Meier overall survival curves for treatment regimens in the three risk subgroups. Scores for the three subgroups ranged from (A) low risk: ≤ 206; (B) intermediate risk: (206, 282]; and (C) high risk: >282. Comparison of CSS in patients receiving chemotherapy alone, surgery alone, or surgery plus chemotherapy in the different risk groups