Update on Colon Cancer Screening and Prevention

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Update on Colon Cancer Screening and Prevention

• Patrick R. Pfau, M.D.,
• University of Wisconsin Medical School,
• Director of Gastrointestinal Endoscopy
• Section of Gastroenterology and Hepatology

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Colorectal Cancer

• Lifetime incidence 5
• 90 of cases occur after age 50
• One-third of patients with colorectal cancer die
  from the disease
• Only approximately 50 of patients are screened
  for colorectal cancer
• Colorectal cancer is a preventable disease

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Colon polyps

• Two-thirds of polyps are adenomas (dysplasia)
• Adenoma prevalence 25 at age 50 and 50 by age
  70
• Risk of cancer increases with polyp size, number,
  and histology
• The polyp examined is representative of the
  individuals propensity to form polyps and cancer

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Adherence Rates Cancer Screening

• U.S. Adherence
  Rates
• Breast Cancer 69
• Cervical Cancer 86
• Prostate Cancer 75
• Colorectal Cancer 45 63
• Seeff Cancer 2002952211-22
• Sirovich JAMA 20032891414-20

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Colon Cancer Screening When to Begin ?

• Average risk begin at age 50
• Family risk factors
• Primary degree relative doubles risk
• Begin screening at age 40 or 10 years earlier
  than diagnosis of relative
• Colon cancer syndromes (5-10 of colon CA)
• Hereditary non-polyposis colorectal cancer
  (HNPCC)
• Colonoscopy every 1-2 years beginning at age
  20-25
• Familial Adenomatous Polyposis (FAP)

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CRC Screening Guidelines- Average Risk

• GI Consortium
• Annual FOBT
• Flex sig every 5 yrs
• Combination of above
• DCBE every 5 years
• Colonoscopy every 10 years (preferred option
  ACG)
• Winawer Gastroenterology 2003124544-560

• American Cancer Society
• Recommendations now identical to the GI
  consortium
• Smith CA Cancer J Clin 20045441-52

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Quantitative immunochemical FOBT

• Improved detection of hemoglobin as compared to
  guaic based FOBT tests
• Immunochemical FOBT testing uses antibodies to
  human globin expressed in colorectal bleeding.
• 94 sensitivity for cancers and 67 for
  advanced adenomas with approximate 90
  sensitivity in high risk individuals (Ann Int Med
  2007)
• Has not yet been tested in asymptomatic average
  risk patients

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A word about the digital rectal exam
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Sigmoidoscopy Weaknesses

• 20-30 of proximal advanced adenomas are missed
  with sigmoidoscopy
• Sigmoidoscopy particularly poor in women missing
  65 of advanced polyps as opposed to colonoscopy
  (NEJM 2005)
• Would you ever mammogram one breast ?

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Screening Colonoscopy

• Two large cohort studies (Winawer, et al, NEJM
  1993 and Citarda, et al Gut 2001) have
  demonstrated significant reductions in colon
  cancer incidence if colonoscopy with polypectomy
  are performed
• FOBT and sigmoidoscopy that lead to colonoscopy
  with polypectomy have been shown to significantly
  reduce colorectal cancer mortality

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Screening colonoscopy

• Combines the most complete examination of the
  colon with the direct therapy of removing
  dysplastic polyps
• The role of polyps as a precursor to cancer
  provides the rationale for endoscopic screening
  illustrated by the benefit of adenoma removal by
  polypectomy at the time of colonoscopy

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Novel and Emerging Advances in Colorectal Cancer
Screening

• CT colonography/Virtual colonoscopy
• Fecal DNA analysis
• Capsule endoscopy

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CT colonography/Virtual colonoscopy

• Computed tomography procedure that uses helical,
  multiple thin section images along with
  specialized computer programming to provide
  three-dimensional and two-dimensional images of
  the colon

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Virtual Colonoscopy Quiz How many insurance
carriers in the United States and internationally
have approved CT colonography for colon cancer
screening ?

• Physicians Plus
• Unity
• Group Health

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Virtual Colonoscopy - Sensitivity
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Per Patient Analysis of Polyp Detection at UW
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Advanced Adenoma Comparison
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Adenoma Comparison
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Can you tell the difference between these polyps ?
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Remember there is a person attached to every polyp
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Fecal DNA Analysis

• Colorectal cancer is a disease in which many DNA
  mutations associated with carcinogenesis have
  been characterized
• Stool DNA is stable, shed continuously and
  through amplification tests can be detected in
  minute amounts
• Most studied stool test for DNA mutations is a
  multicomponent test that targets point mutations
  at 15 hot spots on K-ras, APC, p53, Bat-26, and
  long DNA

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Fecal DNA Analysis

• Alquist, et al. Gastroenterology 2000 studied
  patients with colon cancers, large adenomas, and
  normal colons
• Sensitivity of 91 for colon cancer, 82 for
  large adenomas and a specificity of 93
• Imperiale, et al. NEJM 2004 studied patients in a
  screening population
• Poor sensitivity for invasive cancers (52) and
  advanced polyps (15)

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M2A Capsule Endoscope

• M2A captures images at 2 fps
• More than 50,000 images are taken
• Field of view 140º
• Min. detectable object Less than 0.1 mm

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Mouth to Cecum
Multiple telangiectasia on a gastric fold
Teeth
Epiglottis
Ileocecal valve
Wall of right colon
Small Intestine
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Summary Colon Cancer Screening

• FOBT, barium enema, sigmoidoscopy
• All recommended but all with significant
  weaknesses
• Will iFOBT make a come back ?
• Screening Colonoscopy
• Standard of care Diagnosis along with therapy
• CT colonography
• Here today Further verification using one
  technology in multicenter study and more
  importantly how CT colongraphy will work with
  standard colonoscopy
• Fecal DNA analysis and Capsule Endoscopy
• Here tomorrow Further refinement and technical
  improvements needed

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• Screen your patient PCP most important
  physician in colon cancer