Surgery for Oligometastatic Gastric Cancer: Defining Who May Benefit

Should surgery be incorporated more actively into the treatment of oligometastatic gastric cancer? Prolonged survival after complete resection is compelling, but favorable postoperative outcomes do not establish that surgery improves survival over systemic therapy alone. The challenge is to identify, before surgery, patients in whom the expected benefit justifies the operative risk and interruption of systemic therapy. Two studies in this issue of the Journal of Gastric Cancer contribute to this task through biological characterization and prognostic stratification. Their findings help refine the populations in which surgical benefit should be tested.

RENAISSANCE provides an essential starting point. This randomized trial evaluated systemic treatment followed by radical surgery in patients with limited metastatic gastric or esophagogastric junction adenocarcinoma, but failed to demonstrate an overall survival advantage [1]. The result argues against routinely adding surgery in the population studied. Exploratory subgroup findings generate hypotheses rather than establish indications, and operative morbidity and disruption of systemic therapy remain integral to evaluating the strategy. Consistent with this uncertainty, the Korean Practice Guidelines for Gastric Cancer 2024 classify conversion surgery for selected patients responding to systemic therapy as investigational, supported by low-level evidence [2].

A reproducible definition of oligometastatic disease is therefore crucial. OMEC-4, published before the reported RENAISSANCE results, defines esophagogastric oligometastatic disease as one organ with no more than three metastases, or one extra-regional lymph node station. For synchronous disease, it recommends systemic therapy followed by restaging before considering local treatment [3]. However, OMEC-4 excludes peritoneal metastases, whereas several Asian surgical studies include limited peritoneal dissemination. This difference highlights the lack of a consistent definition of oligometastatic gastric cancer. Future definitions should specify metastatic compartment, burden, timing, and treatment response, with separate evaluation of peritoneal disease. Such definitions require prospective validation, although conducting prospective studies in patients with stage IV gastric cancer is particularly challenging. This practical difficulty underscores the value of carefully designed observational studies, while their findings must be interpreted with due attention to selection bias.

PASS-META offers relevant observational evidence. Gastrectomy was associated with favorable survival in selected patients with limited metastatic disease, including limited peritoneal involvement [4]. These findings support further investigation of disease extent and patient selection. However, residual confounding and the exclusion of patients receiving preoperative therapy limit treatment-effect inference and applicability to contemporary conversion surgery. The study provides hypotheses to test rather than definitive surgical indications.

In this issue, Wu et al. [5] introduce TIPscore, a serum proteomic measure of tumor–host interactions that may complement anatomical assessment. Its principal contribution is to characterize biological heterogeneity among patients whose metastatic burden appears similarly limited. This approach offers candidate criteria for refining patient selection beyond metastatic location and lesion count. Lee et al. [6] address a complementary question through a PASS-META-derived prognostic model for patients undergoing upfront R0 gastrectomy for peritoneal oligometastatic disease. Their findings highlight differing outcomes even among patients selected for complete resection. The model may support risk assessment and the design of more precisely defined study populations.

Together, these studies strengthen the rationale for incorporating biological and prognostic information into the definition of oligometastatic gastric cancer. Their value lies in helping formulate and test more precise selection criteria. Both require further validation, and neither establishes that patients with favorable predicted outcomes derive additional benefit from surgery. This distinction between prognosis and treatment benefit is central to interpreting their contribution.

Prospective studies should test these criteria using prespecified disease definitions, assessment time points, and score thresholds. Randomized comparisons should determine whether biological or clinical risk groups experience different treatment effects, while assessing overall survival, quality of life, morbidity, and delivery of systemic therapy. Active investigation of surgery for oligometastatic gastric cancer is justified; broad adoption remains unsupported. The articles in this issue advance that investigation by making biological and prognostic heterogeneity more measurable. As evidence accumulates, the definition should evolve toward identifying a reproducible population in whom local treatment adds meaningful benefit. Surgical indications deserve the same rigor as the operations themselves.