C-C motif chemokine ligand 18 (CCL18), mainly produced by M2-polarised tumour-associated macrophages, is implicated in immunosuppression, invasion, and metastasis, whereas IgG4-positive plasma cells may reflect humoral immunoregulation and immune evasion. In this retrospective cohort study, stromal CCL18 expression at the primary tumour invasion front was evaluated in relation to overall survival in 76 patients with node-positive gastric adenocarcinoma. Stromal IgG4 was assessed secondarily, and concordance between primary tumours and matched lymph node metastases was examined. Immunohistochemical evaluation was restricted to the stromal compartment. IgG4 expression was defined as ≥ 10 positive plasma cells per high-power field, and CCL18 expression was dichotomised using study- specific median cut-offs. Median overall survival was shorter in patients with high vs. low primary tumour stromal CCL18 expression (9.3 vs. 23.2 months). In multivariable Cox regression adjusted for age, sex, histologic grade, and pathological stage, high primary tumour stromal CCL18 expression was associated with shorter overall survival; this association persisted after adding stromal IgG4 to the model. Primary tumour stromal IgG4 showed no independent survival association. Concordance was higher for IgG4 than for CCL18. These findings support primary tumour stromal CCL18 as a candidate tumour microenvironment marker associated with shorter overall survival in node-positive gastric adenocarcinoma.