Histological assessment of stromal maturity as a prognostic factor in surgically treated gastric adenocarcinoma

Abstract Aims: Histological assessment of stromal maturity is a potential prognostic factor in colorectal cancer, but its applicability in gastric adenocarcinoma is completely unknown. The aim of this study was to evaluate the feasibility and prognostic significance of assessing stromal maturity in gastric adenocarcinoma. Methods and results: This study was conducted retrospectively in a cohort of 583 gastric adenocarcinoma patients treated surgically in Oulu University Hospital, Finland between 1983 and 2016. The original diagnostic slides were used for assessment of stromal maturity. Patients were divided into mature stroma and immature stroma groups, and stromal maturity was analysed in relation to 5‐year and overall survival (OS). The primary outcome of the study was 5‐year survival, and the secondary outcome was OS. The kappa‐coefficient for interobserver agreement was 0.609. Patients with immature stroma had worse 5‐year survival compared to patients with mature stroma [adjusted hazard ratio (HR) = 1.32, 95% confidence interval (CI) = 1.06–1.64]. Stromal maturity was significantly associated with 5‐year survival in intestinal‐type subgroup (adjusted HR = 0.63, 95% CI = 1.20–2.21), but not in the diffuse‐type subgroup (adjusted HR = 1.21, 95% CI = 0.87–1.70). Conclusions: Stromal maturity is an independent prognostic factor in gastric adenocarcinoma, and it can be analysed with moderate reproducibility