As the proportion of early gastric cancer has been steadily increased in Korea, so has function-preserving surgery. The function preserving surgery is characterized by the minimized extent of gastrectomy, so this implies that bilateral margins are getting shorter than those of standard gastrectomies.

Currently, there is only one way to identify resection margin status in gastric cancer, 'frozen biopsy'. However, it is labor-intensive and time-consuming procedure. In addition, the results rely on the pathologist's expertise, thereby it showed limitation of its accuracy; high false negative rate of signet ring cell carcinoma was reported in a previous study.

Recently, many studies on magnifying endoscopy with narrow band imaging(NBI) demonstrated that this emerging technique is useful to identify the gastric tumor margin more clearly in vivo, compared with conventional indigocarmine chromoendoscopy. So it was hypothesized that NBI may allow reliable delineation of tumor and identification of resection margin status in the specimen after gastrectomy for gastric cancer.

1. Tumor delineation and identification of resection margin:

   After specimen delivery from the abdomen, frozen biopsy is performed before checking tumor margin. After inspection with NBI, the tumor margin is marked with electrocauterization. The tumor size and the lengths of both resection margins are evaluated using a ruler.

2. Pathologic examination:

The specimen is sliced as 4mm interval paralleled to the markings. Tumor size, the status of both resection margins, and microvessel density are evaluated under the 200 magnified view.

Inclusion Criteria:

• The patient from over 20 to under 90 years
• The patient who is diagnosed as gastric cancer clinically by endoscopy or computed tomography
• The patient who is informed and consent about the purpose and contents of this study prior to the participation in this study

Exclusion Criteria:

• The patient who shows far advanced gastric cancer preoperatively or intraoperatively
• The patient with previous medical history of other treatment for gastric caner such as endoscopic resection, chemotherapy, radiation, immunotherapy, and so on

The patient who is diagnosed as early staged gastric cancer preoperatively