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Comparative Evaluation of Immunochemical Fecal Occult Blood Tests for Colorectal Adenoma Detection A nnals of Internal Medicine : February 3, 2009 Seema Qaiyumi, MD Georgetown University Hospital February 17, 2009 Background Colorectal Cancer is the 3 rd most common cancer in the world.

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seema qaiyumi md georgetown university hospital february 17 2009

Comparative Evaluation of Immunochemical Fecal Occult Blood Tests for Colorectal Adenoma DetectionAnnals of Internal Medicine : February 3, 2009

Seema Qaiyumi, MD

Georgetown University Hospital

February 17, 2009

background
Background
  • Colorectal Cancer is the 3rd most common cancer in the world.
  • 1 million new cases and >500,000 deaths per year.
  • Most cases are sporadic and develop from removable precancerous lesions (adenomas) and curable early stage cancer.
  • Screening has a high potential for reducing morbidity and mortality.
  • RCT demonstrate reduced mortality with guaiac based Fecal Occult Blood Testing (FOBT) followed by sigmoid or colonoscopy if FOBT is positive.
fecal occult blood testing
Fecal Occult Blood Testing
  • Guaiac based
  • Chemical reaction on a paper card which detects pseudoperoxidase activity of heme or hemoglobin
  • Limitations
    • Not specific for human hemoglobin
    • False +/- results from compounds in medications or food
    • (undercooked red meat, Vitamin C supplements)
    • Low diagnostic performance for precursors
  • Advantages
    • Low cost
    • Easy to do in physician’s office with adequate training for reading and interpretation
immunochemical fobt
Immunochemical FOBT
  • Use specific antibodies against human blood components to overcome diet/medication restrictions
  • Quantitative FOBTs
  • Qualitative FOBTs
    • Use immunochromatographic technology to allow simple office based analysis
    • Differences exist that may influence the diagnostic performance (especially in detection of precursor lesions)
      • Antibodies used
      • Different detection limits
study aim
Study Aim

Determine and compare performance characteristics of different qualitative immunochemical FOBTs for the detection of colorectal adenomas in a large sample of women and men undergoing screening colonoscopy

methods
Methods
  • Part of ongoing screening study including 20 GI practices in SW Germany from January 2006 -December 2007
  • Patients Included: 1319 patients undergoing routine screening colonoscopy
methods7
Methods
  • Patients excluded
    • Visible rectal bleeding or preceding + FOBT
    • Inflammatory Bowel Disease
    • Colonoscopy within 5 years
    • Stool samples collected after colonoscopy
    • Inadequate bowel prep
    • Incomplete colonoscopy
    • Histologically confirmed diagnosis of CRC
    • Non defined polyps (no histology reports available)
    • Pseudopolyps (likely UC/IBD)
    • President Bush
methods8
Methods
  • Stool collection
    • Participants were given 1 test card for guaiac-based FOBT, a small 60mL container for stool collection, collection tissue and detailed instructions for stool collection
    • Samples were collected at home using specific instructions for collection and storage
    • Samples were brought on the day of colonoscopy and shipped on dry ice to a central lab for analysis
stool tests
Stool Tests
  • Done by PA’s who were blinded to colonoscopy and stool guaiac results
  • Six Immunochemical FOBT’s used
    • Bionexia FOB-plus (Gottingen, Germany)
    • PreventID CC (Bensheim, Germany)
    • ImmoCARE-C (Voerde, Germany)
    • FOB advanced (Ahrensburg, Germany)
    • QuickVue iFOB (San Diego, California)
    • Bionexia Hb/Hp Complex (Gottingen, Germany)
data analysis
Data Analysis
  • Two independent technicians interpreted all FOBT tests
  • Interoobserver reliability was very good (ĸ statistics)
  • Sensitivity and Specificity of each test to detect adenoma was calculated
variation
Variation
  • Based on duration of sample storage prior to testing, no general trend for sensitivity or specificity
  • Whether stool samples were frozen or not did not appear to cause relevant differences based on sensitivity analysis
discussion
Discussion
  • Stool tests are an integral component of CRC screening
  • Useful in patients who are unwilling/unable or when health care resources are limited
  • Marked differences were found when comparing multiple qualitative immunochemical FOBTs
  • Promising results found for only 2 tests:
    • immoCARE-C (25% - 96.7%)
    • FOB advanced (27% - 92.9%)
    • Higher sensitivities found for distal, large and multiple adenomas
other studies
Other Studies
  • Magstream 1000/Hem SP (Tokyo, Japan) compared to colonoscopy (n=21,805)
    • Quantitative immunochemical FOBT based on magnetic agglutination
    • Sensitivity 22.3% - Specificity 95.5%
  • FlexSure OBT (Palo Alto, CA) compared to sigmoidoscopy (n=584)
    • Limited to distal lesions only
    • Sensitivity 29.5% - Specificity 97.3%
  • Studies comparing multiple immunochemical FOBT’s in parallel are few and have small numbers
study strengths
Study Strengths
  • Multiple immunochemical FOBTs compared in parallel
  • All participants had colonoscopies, regardless of FOBT outcome
  • FOB testers and colonoscopy MD’s were blinded to test results
  • Assessed test performance characteristics in the target population for screening (age and risk profile)
  • Distribution of findings (% of adenomas) was in accordance with other studies
study limitations
Study Limitations
  • Stool from only 1 day was collected
    • Underestimates sensitivity
    • Overestimates specificity
  • Stool was stored frozen instead of used fresh
  • Bias: Participants undergoing screening colonoscopy may be more health conscious than the general population
  • Limited by the accuracy of screening colonoscopy to detect precancerous lesions
summary
Summary
  • Qualitative immunochemical FOBT could be an option for future CRC screening
  • Careful evaluation of each test is needed given the differences among tests
  • Only 2 of the tests showed specificity needed to become part of routine testing of average risk populations
references
References
  • Hundt, Sabrina MSc; Haug, Ulrike PhD; Brenner, Hermann MD, MPH. Comparative Evaluation of Immunochemical Fecal Occult Blood Tests; Annals of Internal Medicine. February 3, 2009.
  • Allison JE, Sakoda LC, Levin TR, Tucker JP, Tekawa IS, Cuff T, et al. Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics. Journal of the National Cancer Institute. 2007. 99:1462-70.
  • Morikawa T, Kato J, yamaji Y, Wada R, Mitsushima, T, Shiratori Y. A comparison of the immunochemical fecal occult blood test and total colonoscopy in the assympomatic population. Gastroenterology. 2005. 129: 422-8.
  • Ferlay J, Bray F, Pisani, P, Parkin DM. GLOBOCAN 2002: Cancer Incidence, Mortality and Prevalence worldwide. IARC Cancer Base No 5. Version 2.0. Lyon France. IARC Pr 2004.
  • Arnold CN, Goel A, Blurm HE, Boland CR. Molecular pathogenesis of colorectal cancer; implications for molecular diagnosis. Cancer. 2005. 104: 2035-47.
  • Hewitson P, Glasziou P, Irwig L, Towler B, Watson E. Screening for colorectal cancer using the fecal occult blood test, Hemoccult. Cochrane Database. Systematic review 2007: CD001216.
  • Jaffe RM, Kasten B, Young DS, MacLowry JD. False-negative stool occult blood tests caused by ingestion of ascorbic acid (Vitamin C). Annals of Internal Medicine. 1975; 83: 824-26.