Lymphovascular invasion in early gastric cancer: impact of ancillary D2-40 and elastin staining on interobserver agreement

Aims: Lymphatic invasion (LI) and venous invasion (VI) are the strongest risk factors for lymph node metastasis in patients with early gastric cancer, and may predict their prognosis. We aimed to investigate interobserver agreement among pathologists before and after adding ancillary staining for diagnosing LI and VI in this setting.

Methods and results: This retrospective study included 100 specimens of submucosal invasive gastric cancer from 100 patients treated using endoscopic resection. Three pathologists (expert, intermediate and trainee experience levels) independently evaluated individual LI and VI status using haematoxylin and eosin (H&E)-stained slides, and re-evaluated their decisions by reviewing corresponding D2-40-stained and elastin-stained slides. Interobserver agreement was assessed using κ statistics. With the ancillary D2-40 staining, there was an improved agreement for LI diagnoses between the expert and intermediate pathologist (H&E κ = 0.78, D2-40 κ = 0.85) and between the expert and trainee pathologist (H&E κ = 0.37, D2-40 κ = 0.56). With the ancillary elastin staining, there was an improved agreement for VI diagnoses between the expert and intermediate pathologists (H&E κ = 0.25, elastin κ = 0.63) and between the expert and trainee pathologists (H&E κ = 0.29, elastin κ = 0.45).

Conclusions: With both the ancillary D2-40 and elastin staining there was an improved interobserver agreement for LI and VI diagnoses, regardless of the pathologist's experience. This ancillary staining may be useful in improving the accuracy of LI and VI diagnoses, helping to improve the risk stratification of early gastric cancer patients.