Operable gastric adenocarcinoma with different histological subtypes: Cancer-specific survival in the United States.

Background/Aims: Gastric signet ring cell carcinoma (GSRC), a subtype of adenocarcinoma, has been considered a histological type with poor survival. We aimed to compare the survival outcomes between patients with GSRC and patients with gastric non-signet ring cell adenocarcinoma (NGSRC) and constructed a nomogram to predict gastric adenocarcinoma-specific survival (GCSS). Patients and Methods: We identified 10,031 patients with gastric adenocarcinoma (GA) from the surveillance, epidemiology, and end results (SEER) database and stratified them into two histological type groups: GSRC and NGSRC. We used propensity score matching and identified 4304 patients (training cohort) to assess the effect of the histological type on GCSS with Kaplan-Meier curves, and constructed a predictive nomogram. The accuracy of the nomogram was tested on the remaining 5727 patients (validation cohort) with concordance index (C-index) values, calibration curves, and receiver operating characteristic (ROC) curve analysis. Results: We found that the histological type SRC was not associated with significantly poor survival (5-year survival rate: 46.1% vs 46.7%, P = 0.822). GSRC patients had similar GCSS rates compared to those with NGSRC in each tumor, node, and metastasis (TNM) stage (all P > 0.05). The nomogram showed that histological type was a relatively weak predictor of survival. The C-index value of the nomogram for predicting survival was 0.720, similar to that in the validation cohort (0.724). Conclusions: Patients with GSRC had a similar prognosis to those with NGSRC. The proposed nomogram allowed a relatively accurate survival prediction for operable GA patients after gastrectomy.