Objective To explore the prognostic factors in patients with primary T_1a stage gastric cancer (GC) based on the Surveillance, Epidemiology, and End

Results (SEER) database and analyze the survival prognosis of patients in different tumor maximum diameter subgroups under various treatment modalities.

Methods A retrospective analysis was conducted on the clinical data of patients diagnosed with primary T_1a stage GC, also known as early gastric cancer (EGC), from 2000 to 2022 in the SEER database. Variables included in the analysis encompassed demographic information and disease characteristics. According to pathological classification, the selected EGC patients were divided into differentiated early gastric cancer (D-EGC) patients and undifferentiated early gastric cancer (UD-EGC) patients. A stepwise Cox proportional hazards regression model was employed to identify factors independently associated with the outcome event (all-cause mortality) in the overall EGC patients, D-EGC patients, and UD-EGC patients. Based on the tumor maximum diameter, the overall EGC patients were categorized into three groups: ≤2 cm group, >2 to 3 cm group, and >3 cm group. Kaplan-Meier survival curves and the Log-rank test were used to analyze survival differences among different tumor maximum diameter subgroups under various treatment modalities and pathological classifications.

Results A total of 943 patients with T_1a stage GC were finally included and divided into survival group (n=487, accounting for 51.64%) and death group (n=456, accounting for 48.36%) according to the outcome event (all-cause mortality). There were statistically significant differences between the survival and death groups in terms of age, tumor maximum diameter, gender, human race, N stage, treatment modality, and the number of regional lymph nodes (P < 0.05). The results of the stepwise Cox proportional hazards regression analysis revealed that older age, gender (male), unmarried or other marital status, no treatment, and larger tumor maximum diameter were independent risk factors for the outcome event in the overall EGC patients (P < 0.05). Older age, gender (male), no treatment, and larger tumor maximum diameter were independent risk factors for the outcome event in D-EGC patients (P < 0.05), while being Asian or Pacific Island/American Indian/Alaska native (API/AI/AN) people was an independent protective factor (P < 0.05). Older age, gender (male), unmarried or other marital status, and no treatment were independent risk factors for the outcome event in UD-EGC patients (P < 0.05). Restricted cubic spline (RCS) analysis showed that the risk of the outcome event significantly increased when the age of patients with overall EGC, D-EGC, and UD-EGC exceeded 68.0 years, 68.0 years, and 64.5 years, respectively. Kaplan-Meier survival curve analysis indicated that among the overall EGC patients, the median survival time of patients without treatment in different tumor maximum diameter subgroups was all shorter than 10 months, with statistically significant differences compared to patients receiving other treatment modalities (P < 0.01).

Conclusion The survival prognosis analysis of patients with primary T_1a GC based on the SEER database, including survival differences among the overall EGC patients, patients with different pathological classifications, and patients in different tumor maximum diameter subgroups under various treatment modalities, can provide a reference for the selection of treatment modalities for T_1a GC.