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  • • Colorectal cancer second leading cause of cancer deaths (after lung)

    • Adenocarcinoma accounts for 95% of malignant colorectal tumors

    • Genetic predisposition in familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer (HNPCC)

    • Conditions predisposing to colorectal cancer

    • -Ulcerative colitis

      -Crohn colitis

      -Schistosomal colitis

      -Exposure to radiation

      -Presence of ureterocolostomy

    • Possible dietary influences

    • -High caloric intake

      -High saturated fat intake

      -Decreased dietary calcium

      -Decreased fiber intake

    • Carcinogenesis multi-step process involving dysfunction of tumor suppressor genes, including APC, DCC, P53

    • Distribution of colorectal cancer

    • -25% right colon

      -10% transverse colon

      -15% left colon

      -20-50% rectosigmoid colon

    • Spreads through direct extension, hematogenously, lymph nodes, transperitoneal, intraluminal

    • Synchronous lesions occur in 3-5%

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Epidemiology

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  • • 156,000 cases diagnosed per year

    • 65,000 colorectal cancer deaths per year

    • Incidence increases with age

    • Colon cancer is more common in women than men

    • Rectal cancer is more common in men than women

    • Multiple synchronous colonic cancers found in 5% of patients

    • 5% lifetime risk

    • 6-8% occurs before age 40 years

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Symptoms and Signs

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  • • Symptoms depend on anatomic location and extent of lesion

    • Right colon lesions may become large before symptoms develop

    • -May cause occult bleeding, anemia

    • Left colon lesions often cause crampy abdominal pain

    • Large bowel obstruction ~ 10% cases

    • Fatigue, weakness, vague abdominal pain, abdominal mass (< 10%), anemia

    • Constipation alternating with increased frequency of defecation

    • Dark or blood tinged stool

    • Change in stool caliber

    • Rectal cancers

    • -Hematochezia

      -Tenesmus

    • Physical exam findings may include abdominal mass, lymphadenopathy, rectal mass

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Laboratory Findings

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  • • Patients may have microcytic, hypochromic anemia

    • Positive occult blood on guiac stool test

    • Carcinoembryonic antigen (CEA) elevation (nonspecific, more useful for surveillance following resection), prompts additional imaging (CT scan)

    • Elevation of biochemical markers (nonspecific): CA 19-9, CA 72-4, plasma prolactin

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Imaging Findings

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  • • Contrast enema-filling defect, "apple core lesion"; constricted area or intraluminal mass

    Total colonoscopy: Should be performed to evaluate lesion and presence of synchronous lesions

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  • • Ulcerative colitis

    • Crohn colitis

    • Ischemic colitis

    • Parasite infection, amebiasis

    • Diverticulitis

    • Diverticulosis

    • Appendicitis

    • Peptic ulcer disease

    • Other neoplasms of colon/rectum

    • -Lymphoma

      -Carcinoid

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  • • Complete history (including family) and physical exam

    • Total colonoscopy with biopsy

    • Obtain plain abdominal x-ray and water-soluble contrast enema in patients with bowel obstruction

    • Once diagnosis is made, staging studies should be performed

    • -Chest x-ray

      -CT scan:Helpful to assess extramural extension or metastatic lesions

      -Liver function tests

    Endorectal US: Helpful for determining depth of invasion in rectal lesions

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When to Admit

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  • • Bowel obstruction/perforation

    • Hemodynamically significant lower GI bleeding

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  • • Mainstay of management is surgical with good mechanical bowel prep

    • Lesion and regional lymphatic drainage basin need to ...

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