Evaluating peritoneal elastic laminal invasion to improve stratification of patients with pT3 gastric cancer

Elastic laminal invasion (ELI), defined as tumor invasion beyond the peritoneal elastic lamina, may affect gastric cancer (GC) prognosis, though limited data exist on this relationship.

We retrospectively reviewed representative pathological slides from 396 patients with pT3 or pT4a GC who underwent curative resection to assess the association between ELI and relapse-free survival (RFS) and overall survival (OS).

The 5-year RFS of pT3 GC with negative ELI was 85.9%, which was better than the 55.9% of that of ELI-positive pT3 (P < 0.001) or pT4a (51.3%) GC (P < 0.001). Similarly, the 5-year OS of ELI-negative pT3 GC was 90.4%, while the corresponding values for ELI-positive pT3 and pT4a were 67.0% (P < 0.001) and 63.6% (P < 0.001), respectively. Multivariate analysis revealed that the most significant prognostic factors for RFS were pT factors (i.e., pT3 with ELI/pT4), tumor size (≥ 80 mm), and nodal metastasis. We subdivided our cohort of patients with pathological stage II (pT3N0, pT3N1) GC into ELI-negative and ELI-positive subgroups, and found that the ELI-negative ones had better RFS percentages than those who were ELI-positive or stage III (P = 0.002 and P < 0.001, respectively).

ELI-positive pT3 GC has a worse prognosis than its ELI-negative counterpart, comparable to that of pT4a. These findings suggest a need to revisit the pT grading system in GC.