The clinical meaning of a nonstructural pattern in early gastric cancer on magnifying endoscopy.

Background: In the field of colorectal cancer, the presence of a nonstructural pattern in magnifying colonoscopy means that cancer involves the submucosal layer. Since en bloc EMR was developed, differentiation between mucosal and submucosal cancer is a critical issue in the management of gastric cancer. In this study, we evaluated the clinical meaning of a nonstructural pattern in magnifying gastroscopy.

Methods: Between April 2002 and July 2003, 59 patients with 50 cancers and 11 adenomas were enrolled in this study. A cancerous lesion was subclassified into a differentiated-type group or a undifferentiated-type group according to histologic type. Before treatment, magnifying endoscopic observation was performed. After EMR or surgical intervention, resected specimens were observed by using stereomicroscopy. In both in vivo magnifying endoscopic and in vitro stereomicroscopic observations, the presence of a nonstructural pattern on the lesion was investigated. Compared with histologic findings, the clinical meaning of the presence of a nonstructural pattern on the gastric neoplastic lesion was evaluated.

Results: A nonstructural pattern could not be confirmed in any adenomas and in 29 of 31 mucosal differentiated cancers. However, in 9 of 11 submucosal cancers, a nonstructural pattern could be identified.

Conclusions: The presence of a nonstructural pattern appeared to be a useful marker to not proceed with EMR of gastric cancer.