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Dr.sahel hammouri EPIDEMIOLOGY one of the most common cancers in the world US: 4th most common cancer (after lung, prostate, and breast cancers) 2nd most common cause of cancer death (after lung cancer) 2001: 130,000 new cases of CRC 56,500 deaths caused by CRC Typical sites of incidence and sympoms of colon cancer Changes resulting in colon cancer Risk factors for CRC Age Adenomas, Polyps Sedentary lifestyle, Diet, Obesity Family History of CRC Inflammatory Bowel Disease (IBD) Hereditary Syndromes (familial adenomatous polyposis (FAP)) Development of CRC result of interplay between environmental and genetic factors Central environmental factors: diet and lifestyle 35% of all cancers are attributable to diet 50%-75% of CRC in the US may be preventable through dietary modifications Dietary factors implicated in colorectal carcinogenesis consumption of red meat animal and saturated fat increased risk refined carbohydrates alcohol Dietary factors implicated in colorectal carcinogenesis dietary fiber vegetables fruits decreased risk antioxidant vitamins calcium folate (B Vitamin) Symptoms associated with CRC weight loss rectal bleeding loss of appetite change in bowel habits night sweats obstruction fever abdominal pain & mass iron-deficiency anemia Staging of CRC TNM system Primary tumor (T) Regional lymph nodes (N) Distant metastasis (M) Staging of CRC Dukes staging system A B C1 C2 D Mucosa Into or through M. propria Into M. propria, + LN ! Through M. propria, + LN! distant metastatic spread 80% 50% 40% 12% <5% Sites of metastasis Via blood Via lymphatics Per continuitatem Liver Lymph nodes Lung Abdominal wall Brain Nerves Bones Vessels Therapy Surgical resection the only curative treatment Likelihood of cure is greater when disease is detected at early stage Early detection and screening is of pivotal importance Screening What is screening? a public health service in which members of a defined population are examined to identify those individuals who would benefit from treatment to benefit: to reduce the risk of a disease or its complications Types of Screening fecal occult blood test (FOBT) chemical test for blood in a stool sample. annual screening by FOBT reduces colorectal cancer deaths by 33% Flexible sigmoidoscopy can detect about 65%–75% of polyps and 40%–65% of colorectal cancers. rectum and sigmoid colon are visually inspected Current Screening Guidelines regular screening for all adults aged 50 years or older is recommended FOBT every year flexible sigmoidoscopy every 5 years total colon examination by colonoscopy every 10 years or by barium enema every 5–10 years Molecular Biology & Pathology CRCs arise from a series of histopathological and molecular changes that transform normal epithelial cells Intermediate step is the adenomatous polyp Adenoma-Carcinoma-Sequence (Vogelstein & Kinzler) Polyps occur universally in FAP, but FAP accounts for only 1% of CRCs Adenomatous Polyps in general population: 33% at age 50 70% at age 70 Summary CRC is a leading cause of death Early stages are detectable Screening can prevent CRC Katie Couric: http://www.nccra.com/about/videos.htm thanks