Early gastric cancer: detection and endoscopic treatment

Early Gastric Cancer (EGC) is defined as a neoplasm confined to the mucosa or submucosa regardless of regional lymph node metastasis. The rate of EGC, which varies by country, is up to 40-60% of all gastric cancer cases in Japan, whilst in Western countries, the proportion remains at 5-10%. There is a strong male predominance in EGC. The average 5-year survival rate of patients with EGC reached over 90% in Japanese and European data.

Many EGC patients present with symptoms suggestive of a benign gastric ulcers. The combination of serum pepsinogen and Helicobacter pylori status may provide even more sensitive information for screening. However high-quality endoscopic evaluation with biopsy is the key to diagnosis. To improve the quality of observation several endoscopic imaging modalities have been developed for the diagnosis of early gastric cancer. Endoscopic resection is a viable alternative to surgery for curative treatment of EGC, with similar long term results. Endoscopic mucosal resection (EMR) of EGC without any risk of lymph node metastasis was developed in Japan in the 1980s, and it has been one of the standard treatments of EGC for nearly 20 years. Recently, several EMR techniques developed in Japan have been accepted and done in Western countries. These EMR techniques are safe and efficacious but unsuitable for large lesions.

Because we could not remove a large lesion in 1 fragment, which was very important for the precise diagnosis of tumor depth, local recurrence increased in large-lesion cases. An innovative procedure using newly developed endoscopic knives, called endoscopic submucosal dissection (ESD), was developed in the late 1990s, which made it possible to remove a large lesion en bloc.

Theoretically, ESD has no limitation with respect to tumor size; therefore, it is expected to replace the surgical treatment in some situations. Although ESD has spread throughout Japan within a short period, there remain several disadvantages, such as a higher incidence of complications and a requirement of higher endoscopic skills compared to those of conventional EMR methods.