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Introduction
  • Second leading cause of cancer deaths
  • Risk factors include
    • family history
    • IBD
    • colorectal polyps
    • low fiber, high fat diet (now controversial)
    • diet low in vitamin A, E, C, and selenium
  • Familial Adenomatous Polyposis Syndrome (FAP) 
    • 100% will develop colon cancer without resection
  • Hereditary Nonpolyposis Colorectal Cancer (HNPCC) 
    • where a person has a single polyp that can turn to cancer
    • Lynch Syndrome I (HNPCC I)
      • autosomal dominant predisposition to colorectal CA
      • right sided predominance (70% proximal to splenic flexure)
    • Lynch Syndrome II (HNPCC II)
      • same features of Lynch I
      • plus extra-colonic cancers especially
        • endometrial carcinoma
        • carcinoma of ovary, small bowel, stomach, pancreas
        • transitional cell CA of the ureter and renal pelvis
Presentation
  • Iron deficiency anemia in an elderly male is colon cancer until proven otherwise!
  • Right sided lesions
    • microcytic anemia and unrecognize blood loss
    • postprandial discomfort
    • fatigue
  • Left sided lesions
    • Change in bowel habits
    • pencil thin stools
    • abdominal obstruction
    • abdominal mass
    • gross red blood (hematochezia)
    • tenesmus
    • rectal mass
  • Systemic symptoms (malaise, fatigue, weight loss)
Evaluation
  • Barium enema X-ray
  • Colonoscopy with biopsy  
    • Lynch syndrome: every 1-2 years beginning at age 25 
  • If a patient presents with evidence of metatasis to the liver, abominal CT is the most appropriate first step.  
  • Dukes system with 5 year survivals

    Classification Description 5y survival
    Duke A Tumor limited to mucosa or submucosa (mus. propia) 80%
    Duke B1 Tumor invades but not through muscle wall 60%
    Duke B2 Tumor penetrates entire wall but no node involvement. 55%
    Duke C1 Tumor into but not through wall but positive lymph nodes 30%
    Duke D Distant metastasis regardless of invasion <5%
Differential
  • Diverticular disease, IBD, benign polyps,infectious colitis, upper GI bleed
Treatment
  • Surgical resection following the pattern of lymphatic and vascular drainage is the primary therapy
  • Node negative (Duke A and B) disease is resected and followed
  • Node positive disease is resected and followed by chemotherapy or radiation
  • Metastatic colon cancers are resected, including small to moderate liver mets 
  • Can track CEA (70% of colorectal cancers secrete) post treatment
  • Consider prophylactic colectomy for patients with FAP
Prognosis, Prevention, and Complications
  • Regardless of stage, the overall five year survival is 35%
  • Screening: If no strong risk factors, > 40 yo then
    • annual digital exam and stool guiac (if positive colonoscopy)
    • flex sigmoidoscopy or colonoscopy q 3-5 years > 50 yo
    • if family h/o then colonoscopy at age 40 or 10 years prior to age of diagnosis, which ever is earlier  
  • Post resection follow up
    • CEA q 3 mos. X 3 yrs
    • Colonoscopy at 6 mos, 12 mos, yearly x 5 yrs
    • no further treatment needed post-resection of pedunculated adenomatous polyp without evidence of invasion on histology 

 

 

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