Endoscopy in screening for digestive cancer.

The aim of this study is to describe the role of endoscopy in detection and treatment of neoplastic lesions of the digestive mucosa in asymptomatic persons. Esophageal squamous cell cancer occurs in relation to nutritional deficiency and alcohol or tobacco consumption. Esophageal adenocarcinoma develops in Barrett's esophagus, and stomach cancer in chronic gastric atrophy with Helicobacter pylori infection. Colorectal cancer is favoured by a high intake in calories, excess weight, low physical activity. In opportunistic or individual screening endoscopy is the primary detection procedure offered to an asymptomatic individual. In organized or mass screening proposed by National Health Authorities to a population, endoscopy is performed only in persons found positive to a filter selection test. The indications of primary upper gastrointestinal endoscopy and colonoscopy in opportunistic screening are increasingly developing over the world. Organized screening trials are proposed in some regions of China at high risk for esophageal cancer; the selection test is cytology of a balloon or sponge scrapping; they are proposed in Japan for stomach cancer with photofluorography as a selection test; and in Europe, America and Japan; for colorectal cancer with the fecal occult blood test as a selection test. Organized screening trials in a country require an evaluation: the benefit of the intervention assessed by its impact on incidence and on the 5 year survival for the concerned tumor site; in addition a number of bias interfering with the evaluation have to be controlled. Drawbacks of screening are in the morbidity of the diagnostic and treatment procedures and in overdetection of none clinically relevant lesions. The strategy of endoscopic screening applies to early cancer and to benign adenomatous precursors of adenocarcinoma. Diagnostic endoscopy is conducted in 2 steps: at first detection of an abnormal area through changes in relief, in color or in the course of superficial capillaries; then characterization of the morphology of the lesion according to the Paris classification and prediction of the risk of malignancy and depth of invasion, with the help of chromoscopy, magnification and image processing with neutrophil bactericidal index or FICE. Then treatment decision offers 3 options according to histologic prediction: abstention, endoscopic resection, surgery. The rigorous quality control of endoscopy will reduce the miss rate of lesions and the occurrence of interval cancer.