questions 8

Colon Cancer

Topic updated on 11/10/17 8:07am

  • 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
  • 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)
  • 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%
  • Diverticular disease, IBD, benign polyps,infectious colitis, upper GI bleed
  • 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 



Qbank (4 Questions)

(M3.ON.13) A 28-year-old male has a family history of colon cancer. His father was diagnosed with colorectal adenocarcinoma at age 55. At what age should this patient begin colonoscopy screening? Topic Review Topic

1. 35
2. 40
3. 45
4. 50
5. 55

(M3.ON.44) An elderly man undergoes a routine colonoscopy and is found to have a 1.5 cm colon polyp which is subsequently completely excised. In the laboratory, the pathologist is able to accurately determine the depth of invasion and completeness of excision. The pathology report notes that the margin of excision was not involved. The patient needs no further treatment if which of the following is true? Topic Review Topic

1. The patient has a negative fecal occult blood test
2. The polyp is pedunculated
3. The patient is over age 65
4. The patient has no family history of colon cancer
5. The cancer is not poorly differentiated

(M2.ON.79) A 61-year-old male presents to his primary care physician with several months of weight loss, vague right upper quadrant pain, and thin-caliber stools. His medical history is notable for 50-pack years of smoking and obesity. On exam, he appears chronically ill and has firm hepatomegaly. His labs reveal a hemoglobin of 10.7 g/dL and mildly elevated ALT and AST. What is the most appropriate next step? Topic Review Topic

1. Liver biopsy
2. Abdominal CT
3. Colonoscopy
4. Bone marrow biopsy

(M2.ON.4754) A 72-year-old man presents to his primary care physician complaining of increasing difficulty sleeping over the last 3 months. He reports waking up frequently during the night because he feels an urge to move his legs, and he has a similar feeling when watching television before bed. The urge is relieved by walking around or rubbing his legs. The patient’s wife also notes that she sometimes sees him moving his legs in his sleep and is sometimes awoken by him. Due to his recent sleep troubles, the patient has started to drink more coffee throughout the day to stay awake and reports having up to 3 cups daily. The patient has a past medical history of hypertension and obesity but states that he has lost 10 pounds in the last 3 months without changing his lifestyle. He is currently on hydrochlorothiazide and a multivitamin. His last colonoscopy was when he turned 50, and he has a family history of type II diabetes and dementia. At this visit, his temperature is 99.1°F (37.3°C), blood pressure is 134/81 mmHg, pulse is 82/min, and respirations are 14/min. On exam, his sclerae are slightly pale. Cardiovascular and pulmonary exams are normal, and his abdomen is soft and nontender. Neurologic exam reveals 2+ reflexes in the bilateral patellae and 5/5 strength in all extremities. Which of the following is most likely to identify the underlying etiology of this patient's symptoms? Topic Review Topic

1. Dopamine uptake scan of the brain
2. Trial of iron supplementation
3. Colonoscopy
4. Trial of reduction in caffeine intake
5. Trial of pramipexole

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