Early gastric carcinoma with lymphoid stroma associated with a low risk of lymph node metastasis and favorable prognosis: a multicenter study in a Chinese population

Objective Gastric carcinoma with lymphoid stroma is a rare subtype of gastric carcinoma. The clinicopathological features and prognosis of early gastric carcinoma with lymphoid stroma (EGCLS) remain elusive, especially in Chinese populations. Methods In this study, we investigated 42 consecutive EGCLSs and compared its clinicopathological, molecular, and prognostic characteristics with those of concurrent 1275 Non-EGCLSs with the same pT1b stage, and those of exactly matched Non-EGCLSs in a 1:1 ratio. Results Compared to Non-EGCLS, EGCLS displayed significantly higher frequencies of the depressed macroscopic type, deep submucosal (SM2) invasion, poor tumor differentiation, and intermediate tumor budding grade, but significantly lower frequency of lymph node metastasis (LNM). After propensity score matching, EGCLS still demonstrated a significantly lower frequency of LNM than Non-EGCLS. Independent risk factors of LNM in submucosal early gastric carcinomas included Non-EGCLS histology, female sex, tumor size ≥ 3.1 cm, elevated and depressed macroscopic types, non-cardiac location, SM2 invasion, lymphovascular invasion, and intermediate-high tumor budding grades. Compared to the exactly matched Non-EGCLSs, EGCLS demonstrated a significantly higher prevalence of either Epstein-Barr virus (EBV) positivity or mismatch repair protein deficiency, wild-type P53 expression, PD-L1 positivity, the depressed macroscopic type, but significantly lower frequencies of lymphovascular invasion. The 5-year overall survival rate was significantly higher in EGCLS (97.1%) than in the matched Non-EGCLSs (91.9%, P = 0.011). Conclusions Despite poor tumor differentiation and deep invasion, EGCLS showed a low LNM rate, favorable prognosis, and a high proportion of cases with PD-L1 positivity.