Colon Off The Significance Of The Cells And Their Mutations In Genetic Testing In The Diagnosis Of Colorectal Cancer

Background and Objectives Colorectal cancer is one of the most common maligancy. Early detection and diagnosis is the key to improve the survival rate of the patients. Screening of persons who are susceptible to colorectal cancer plays an important role in early detection of the disease.At present, the tests aimed at early diagnosis are faecal occult blood test(FOBT) and eolonoscopy. FOBT is a non-invasive test, but it gives a certain of false positives and false negative. Colonoscopy is the most effective method for detection of colorectal cancer,however,it is an invasive test and has to high cost. Therefore colonoscopy could not serve as a optimal means for primary screening. In human ,entire colon epithelial cells are renewed in 3days or 4 days.The cells on the surface of the colonic mucosa are continuously shed into the lumen and eliminated from the intestinal tract in the faeces. Detection of colorectal exfoliated epithelial cells and their gene mutations may provide another non-invasive way of screening and early diagnosis of colorectal cancer. We attempted to improve the approaches of isolating exfoliated cells and extracting its DNA from faecal ,further to analyze the roles of exfoliated cells and its gene mutations in diagnosis of colorectal cancer. Methods 1. Improving the method of isolation exfoliated cells from faece. Thirty- one patients with colorectal cancer were entered in our study. Exfoliated cells in the stool of patients were isolated by two methods of elutriation and Imrnonumagnetic beads (1MB). The method of 1MB was III performed according to Loktionov抯 method, and Elutriation means was Iyengars method with slight modification. The elutriation procedure was follows: a) 3g-5g fresh stools were dispersed with 50-lOOm! of dispersing medium consisting of Minimum Essential Medium (MEM). MEM asic contained 500 units IL penicillin , 500mg IL streptomycin sulfate, 1 .25mg/L amphotericin B,5mmolIL N-acetyicysteine and 1 OgIL bovine serum albumin(BSA). b) The dispersed suspension was filtered through 600 p m sieve,then an excess of boric acid was added to the filtrate. c) the filtrate was sequentially filtered through 150 I~?m and 70 ii m sieves, and centrifuged for 10 minute at 1500 r/min,such centrifi.tgation resulted in a pellet containing the desired exfoliated cells, so removed the supernatant from the pellet. d) the pellet was resuspended by 5m1 resuspending solution , the resuspending solution was added to 2Oml 95% alcohol and centrifuged for 10 minute. e) removed the supematant from the pellet. Slides were made with the pellet, the slides were fixed and stained with Hematoxylin-Eosin(HE),finally they were read blindly by a cytotechnician. 2. Detecting exfoliated cells in stool. One hundred and eighty individuals were selected , forty 梥even of these had pathological confirmation of colorectal maligancy 46patients with colorectal cancer and lpatient with lymphoma. The other 133 persons had no colonoscopic evidence of colorectal maligancy and therefor served as control. The control group was consisted of 50 healthy individuals, 18 cases of ulcerative colitis, 19 chronic colitis,26 patients with colorectal adenoma,16 cases of gastric carcinoma and 4 cases of esophageal carcinoma. Exfoliated cells in the stool were isolated by...