An endoscopic staining method for detection and operation of early gastric cancer

The long term survival rate of gastric cancer has been much improved, and the 5-year survival rate in our institute was 42% with a significant difference between 29% in the advanced stage and 94% in the early stage. This result means that gastric cancer must be detected and treated early as possible. However, the diagnosis of early gastric cancer may remain extremely difficult even for an excellent endoscopist. Therefore, in order to clearly recognize early gastric cancer, an endoscopic staining method with methylene blue has been studied. In this method, one capsule of 150 mg methylene blue is swallowed with a small amount of proteinase solution 3 hours before endoscopy. Gastroscopy is performed routinely after this preparation. This procedure was performed on 153 gastric cancers and 137 of them (89.5%) have been successfully dyed in dark blue. In several cases, with this method, the actual borderline between the normal mucosa and the malignant extent was clearly recognized and resection line was decided. Introduction of methylene blue into the stomach could also stain the intestinalized epithelium of the gastric mucosa. Differential diagnosis of the dyed intestinal metaplasia and the dyed carcinoma seems to be very easy, because both gastric lesions have the characteristic dyed patterns. Mechanism of this phenomenon has been considered to be due to an absorption of the dye in the intestinal metaplasia, and in the gastric cancer, many factors may be involved, among which are the infiltration or diffusion of the dye into the cancerous tissue, the absorption from the abnormal epithelium, and the staining of the necrotic tissue.