Definition and Staging of Early Esophageal, Gastric and Colorectal Cancer

Abstract

Accurate diagnosis of gastrointestinal (GI) cancer in early stages, endoscopically showed as superficial noninvasive lesions, is the current optimal strategy for optional outcome. “Superficial” GI cancer is defined as both mucosal and submucosal cancer with or without lymph node metastases. Curability however, is related to the risk of lymph node metastases, which is the major factor related to long-term outcome. A concept of “early GI cancer” therefore is “local lesion which has no risk of lymph node metastasis”, while “invasive” cancer is a “superficial” cancer with lymph node metastases. According to retrospective studies from surgically rejected specimens of early stage GI cancer with extensive lymph dissection, the rate of lymph node metastases was very low in mucosal carcinomas, which are considered curable by endoscopic rejection alone, but much higher in cases of submucosal invasion. For deep mucosal and slightly submucosal carcinomas there are subtle but important organ specific differences with m3-sm1 esophageal carcinomas to have high risk of lymph node metastases (>20%) despite the superficial appearance, while for m3-sm1 gastric and colorectal lesions have low risk of lymph node metastases and should be also considered for endoscopic treatment. Accurately preoperative staging of GI cancer is the present difficulty in clinics, which is vitally important for choosing appropriate treatment method. Chromoendoscopy in combination with high-resolution, magnification endoscopy and narrow band imaging (NBI) system has been introduced in clinical setting in order to identify subtle GI lesions. The combination of all these techniques permitted real time accurate endoscopic diagnosis of early GI cancer. Moreover, in Japan they have already established standardized endoscopic classifications for staging early GI cancer, using combined macroscopic classification, chromoendoscopy and NBI magnification endoscopy Pit pattern classification is described for colorectal lesions for years. Using NBI magnification it has been established the IPCL pattern classification for early stage easophageal cancer, while for gastric and colorectal cancers there have been described specific NBI magnifying classifications. Based on these classifications a real-time, reliable endoscopic diagnosis of early GI cancer can be made.