血吸虫病和激动的肠炎的诊断和流行病学的Tools（PPT_18页）课件.pptVIP

The Association of Schistosomiasis and Inflammatory Bowel Disease with Colorectal Cancer: Tools for Diagnosis and Epidemiology;In Egypt, schistosomiasis ( from S. haematobium and mansoni)has been strongly linked to bladder cancer. The evidence includes:;Colorectal cancer correlates with prevalence and intensity of shistosome infection. The age of onset of cancer is lower in areas of shcistosome endemicity and length of survival is shorter. Affected individuals usually have a long history of inflammatory large bowel symptoms. The cancers correspond in anatomic location to the area most affected by the parasite.;Pathologically, patients with colonic schistosomiasis manifest epithelial dysplasia, and resemble the changes found in long-standing chronic ulcerative colitis. Chen et al. considered these dysplastic changes as premalignant lesions. Chen et al. Colorectal cancer and schistosomiasis. Lancet 1981 971-3 The evidence associating colorectal cancer and ulcerative colitis and Crohn’s disease is strong. Tumors often occur at the site of chronic inflammation. The absolute risk of developing colorectal hanker is high when extensive disease begins at a young age. 40% of patients diagnosed with pancolitis from ulcerative colitis before age 15 years developed colon cancer during 20 years of follow up in a population-based linkage study in Sweden. DK Podolsky. Inflammatory bowel disease. N Engl J Med. 2002. 347:417-429;S. japonicum lays a very large number of egg, and represents a constant source of irritation. Inflammation involves a series of host reponses that is designed to promote healing and tissue regeneration. These include recruiting specific types of cells, release of mediators and interactions of chemokines with various targets that affect cytological changes. Leukocytes generate reactive oxygen and nitrogen radicals which can damage proteins, membranes and DNA (including the genes controlling cell growth proliferation). Inflammatory cells also release fa