Prognosis of pT3N0M0 gastric cancer (GC) varies greatly, though the major factor conferring poor prognosis is unclear. Subserosal elastic lamina invasion (ELI+) is closely associated with poor outcomes in pT3 colorectal cancer, but related research on GC is unavailable. This study aimed to identify the influence of ELI+ on the prognosis of patients with pT3N0M0 GC and its relationship with serosal invasion using elastic staining. We retrospectively reviewed 94 and 28 patients with pT3N0M0 and pT4aN0M0 GC who underwent gastrectomy between 1994 and 2005. For the former, one section with invasion depth closest to the peritoneal surface and one corresponding paraffin block for each specimen were selected for conventional elastic staining to assess the relationship between ELI+ and patients' clinical characteristics and survival. pT3N0M0 GC specimens were divided into 3 groups based on staining results: ELI+ (N=51), non-invasion (N=31), and unidentified (N=12). ELI+ was closely related to recurrence and lymphovascular invasion. Five-year disease-free (DFS) (46%) and overall (OS) (36%) survival rates were significantly lower in the ELI+ than in the non-invasion or unidentified groups (P<.0001); no obvious difference was found between the ELI+ and pT4aN0M0 groups (P=.25). Multivariate analysis showed ELI+ and recurrence as independent prognostic factors for DFS in pT3 GC patients. In conclusion, elastic staining is an effective and highly feasible method for predicting prognosis and evaluating the serosal invasion depth of pT3 GC. pT3 GC accompanied with ELI+ is an obvious adverse prognostic factor and could be considered a treatment for pT4a GC.
Keywords: Elastic lamina invasion; Elastic staining; Prognostic factor; Serosal invasion; pT3N0M0 gastric cancer.
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