目的 探讨胃癌腹膜转移（GCPM）病人的临床特征及不同治疗模式对其预后的影响，为临床个体化治疗决策提供依据。方法 回顾性分析2015—2024年吉林大学第一医院收治的173例同步GCPM且无其他远处转移病人的临床资料。根据实际接受的治疗分为单纯化疗组、化疗+腹腔热灌注化疗（HIPEC）组、化疗+免疫治疗组、化疗+免疫治疗+HIPEC组、化疗+HIPEC+手术组及化疗+HIPEC+手术+免疫治疗组。采用Kaplan-Meier法估计总生存期（OS），采用Log-rank检验比较组间差异，两两比较采用Holm法校正，采用Cox模型分析预后相关因素；鉴于手术发生于治疗过程中，将手术作为时依协变量，并根据比例风险假设检验结果建立扩展Cox模型，同时进行6个月Landmark敏感度分析，随访截至2026年2月10日。结果 173例病人中147例死亡，中位随访时间为31.13个月，中位OS为13.57个月（95%CI 11.98~15.16个月）。上述6组的中位OS依次为4.10、9.80、12.57、12.50、16.40和18.60个月，总体差异有统计学意义（P<0.001）。经Holm法校正后，化疗+HIPEC+手术组与单纯化疗组比较差异有统计学意义，与其余3种非手术治疗模式比较呈生存优势趋势；化疗+HIPEC+手术+免疫治疗组与4种非手术治疗模式比较，差异均有统计学意义。描述性分析显示，手术组中位OS长于非手术组（17.20个月 vs.12.07个月，P<0.001）。单因素时依Cox分析显示，手术与较低死亡风险相关（HR=0.428，95%CI 0.293~0.624，P<0.001）；多因素扩展Cox分析显示，手术相关效应具有时间依赖性（手术与时间交互项P=0.027）。6个月Landmark分析显示，调整基线因素后，手术组与非手术组死亡风险差异无统计学意义（HR=0.802，95%CI 0.516~1.248，P=0.328）。单因素Cox分析显示，HIPEC（HR=0.457，95%CI 0.325~0.643，P<0.001）和免疫治疗（HR=0.627，95%CI 0.451~0.870，P=0.005）均与较低死亡风险相关。多因素扩展Cox分析显示，贫血、cT4b及cN3b与较高死亡风险相关。结论 GCPM病人不同治疗模式的OS存在差异，包含HIPEC及手术的综合治疗模式显示出较好的生存结局。单因素分析显示，HIPEC和免疫治疗与较低死亡风险相关；考虑治疗时序及基线因素后，手术相关生存优势减弱。贫血、cT4b期及cN3b期与较差预后相关。上述结果为观察性关联，尚不能据此推断特定治疗措施的独立因果效应。

Objective To investigate the clinical characteristics of patients with gastric cancer and peritoneal metastasis (GCPM) and the associations of different treatment modalities with prognosis, thereby providing evidence for individualized clinical decision-making. Methods The clinical data of 173 patients with synchronous GCPM and no other distant metastases who were treated at The First Hospital of Jilin University between 2015 and 2024 were retrospectively analyzed. According to the treatments actually received, the patients were divided into six groups: chemotherapy alone; chemotherapy plus hyperthermic intraperitoneal chemotherapy (HIPEC); chemotherapy plus immunotherapy; chemotherapy plus immunotherapy and HIPEC; chemotherapy plus HIPEC and surgery; and chemotherapy plus HIPEC, surgery, and immunotherapy. Overall survival (OS) was estimated using the Kaplan-Meier method, and intergroup differences were compared using the Log-rank test. Pairwise comparisons were adjusted using the Holm method. Cox regression models were used to analyze prognostic factors. Because surgery was performed during the course of treatment, it was modeled as a time-dependent covariate. An extended Cox model was constructed according to the results of the proportional hazards assumption test, and a 6-month landmark sensitivity analysis was also performed. Follow-up ended on February 10, 2026. Results Among the 173 patients, 147 died during follow-up. The median follow-up time was 31.13 months, and the median OS was 13.57 months (95% CI 11.98-15.16 months).The median OS values in the six treatment groups were 4.10, 9.80, 12.57, 12.50, 16.40, and 18.60 months, respectively, with a statistically significant overall difference (P<0.001). After Holm adjustment, the chemotherapy plus HIPEC and surgery group differed significantly from the chemotherapy-alone group and showed a trend toward a survival advantage over the other three nonsurgical treatment groups. The chemotherapy plus HIPEC, surgery, and immunotherapy group differed significantly from all four nonsurgical treatment groups. Descriptive analysis showed that the median OS was longer in the surgery group than in the nonsurgery group (17.20 months vs.12.07 months, P<0.001). Univariable time-dependent Cox analysis showed that surgery was associated with a lower risk of death (HR=0.428, 95%CI 0.293-0.624, P<0.001).Multivariable extended Cox analysis indicated that the effect associated with surgery was time dependent (surgery-by-time interaction, P=0.027). In the 6-month landmark analysis, after adjustment for baseline factors, the difference in mortality risk between the surgery and nonsurgery groups was not statistically significant (HR=0.802, 95%CI 0.516-1.248, P=0.328). Univariable Cox analysis showed that both HIPEC (HR=0.457, 95%CI 0.325-0.643, P<0.001) and immunotherapy (HR=0.627, 95%CI 0.451-0.870, P=0.005) were associated with a lower risk of death. Multivariable extended Cox analysis showed that anemia, cT4b stage, and cN3b stage were associated with a higher risk of death. Conclusion OS differed among patients with GCPM who received different treatment modalities, and multimodal treatment regimens incorporating HIPEC and surgery were associated with favorable survival outcomes. In univariable analyses, HIPEC and immunotherapy were associated with a lower risk of death; the survival advantage associated with surgery was attenuated after treatment timing and baseline factors were taken into account. Anemia, cT4b stage, and cN3b stage were associated with poorer prognosis. These findings represent observational associations and should not be interpreted as evidence of independent causal effects of specific treatment modalities.