Most professional organizations recommend use of at-home FOBT sample collection over in-office testing because home testing is typically performed on a series of stool samples collected on different days while the in-office test is performed on a single stool sample. Research has shown that the single-specimen office test misses 95% of cancers and precancerous lesions. Testing multiple samples collected on different days increases the likelihood of detecting cancers or precancerous lesions.
The survey found that of the 1,134 primary care physicians who reported ordering or performing FOBT, 25% said they used in-office FOBT exclusively, while 53% reported using both home collection and in-office tests. Furthermore, 61% of the doctors said they use the standard guaiac-based FOBT (gFOBT), while use of the more sensitive guaiac-based test and the immunochemical FOBT (iFOBT) was significantly lower (22% and 8.9%, respectively). Guidelines recommend use of the more sensitive test versions to increase detection of cancer and polyps that can become cancer. Only 44% of doctors who follow guidelines and use home tests have reminder systems to ensure test completion, according to the study.
CDC researchers analyzed data from a 2006-2007 survey conducted by The National Cancer Institute — in collaboration with CDC and the Agency for Healthcare Research and Quality — to find if there were improvements in FOBT since 2000 when a similar survey showed most physicians used the in-office single test. The recent survey shows little change in the practice patterns despite evidence that serial testing is better and recommendations by several professional groups that screening by FOBT should be done using a serial sample system and not be done using a single sample.
Colorectal cancer screening is recommended for adults aged 50 years and older and for younger people with a family or personal history of colorectal polyps, adenomas, cancer, or inflammatory bowel disease. FOBT is an attractive screening method because it is relatively inexpensive, easily accessible, and often the only screening test available to people who have insufficient insurance or otherwise lack access to colonoscopy services.
Doctors may use the in-office FOBT because they are frustrated with poor patient compliance with home collection kits and feel that in-office testing is better than no screening at all. Frequent use of in-office tests by doctors such as obstetrician-gynecologists probably reflects the fact that these doctors routinely perform digital rectal examinations as part of the pelvic examination, so the in-office test is easily accomplished.
Considering these findings, people should talk to their doctors about their options for colorectal cancer screening, particularly if they choose FOBT. If a single-specimen in-office FOBT test is performed, they should ask their doctor about follow-up testing with the more sensitive at-home collection kit. The CDC researchers urge doctors to make more effort to use home collection kits and encourage patients to complete them. Doctors should also use tracking and reminder systems to ensure FOBT test completion and follow-up care.
One positive aspect of the survey revealed some encouraging news: 93% of doctors reported using colonoscopy as a follow-up to a positive FOBT, as recommended in national guidelines.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Centers for Disease Control and Prevention. Press release: New CDC Study Finds Colorectal Cancer Screening Practices Need Improvement. Available online at http://www.cdc.gov/media/pressrel/2010/r100415a.htm through http://www.cdc.gov. Issued April 15, 2010. Accessed May 19, 2010.
Charles Bankhead. Colon Cancer Screening Practices Get Low Marks. MedPage Today. Available online at http://www.medpagetoday.com/HematologyOncology/ColonCancer/19590 through http://www.medpagetoday.com. Published online April 16, 2010. Accessed May 19, 2010.
David Mitchell. High Percentage of Docs Use FOBT Inappropriately, Study Finds. AAFP News Now. Online May 25, 2010 at http://www.aafp.org/online/en/home/publications/news/news-now/clinical-care-research/20100525fobt-study.html through http://www.aafp.org. Accessed June 4, 2010.