Current screening methods for FOBT are often not appropriate

Apr 16 2010

More than 75 percent of primary care physicians in the United States who order or perform the fecal occult blood test (FOBT) as a screening option for colorectal cancer perform an in-office test rather than relying on the home-based test, even though the home-based test is more accurate, a study by the Centers for Disease Control and Prevention has found.

National guidelines recommend that FOBT testing be done with stool samples collected at home. Previous studies have shown that the in-office FOBT, in which a single stool sample is collected by a physician during a digital rectal examination, is ineffective because it misses 95 percent of cancers or polyps that may become cancer. The in-office test is not recommended for colorectal cancer screening.

The study, "Fecal Occult Blood Testing Beliefs and Practices of U.S. Primary Care Physicians: Serious Deviations from Evidence-Based Recommendations," is published online by the Journal of General Internal Medicine at http://www.springerlink.com/content/p7q4n4114510574t/fulltext.pdf.

"Many primary care physicians  continue to use inappropriate FOBT methods to screen for colorectal cancer, thereby missing the potential to save lives," said Marion Nadel, Ph.D., health scientist in CDC's Division of Cancer Prevention and Control, and lead author of the study. "FOBT is an important option for screening, but it must be implemented correctly. People who choose FOBT for screening should use high-sensitivity home tests on an annual basis and be sure to follow-up on any positive result."

In this new study, researchers analyzed data from the 2006-2007 National Survey of Primary Care Physicians' Recommendations and Practices for Cancer Screening conducted by the National Cancer Institute in collaboration with CDC and the Agency for Healthcare Research and Quality.  The scientists looked at whether there has been improvement since 2000, when an earlier study revealed that many primary care physicians used inappropriate methods to implement FOBT.

The current survey included 1,134 primary care physicians who reported ordering or performing FOBT at least once per month.  The researchers examined FOBT implementation practices and physicians' beliefs about and use of the newer tests, the high-sensitivity guaiac-based FOBT and the fecal immunochemical tests.  In the guaiac-based FOBT, the chemical guaiac is used to detect blood in the stool. In the fecal immunochemical tests, antibodies are used to detect blood in the stool.

Of the physicians who reported that they ordered or performed FOBT, 25 percent said they used in-office FOBT exclusively, and about 53 percent reported using both home and in-office tests. Also, 61 percent of primary care physicians used the standard guaiac-based FOBT, while use of the more sensitive guaiac-based test and the fecal immunochemical tests was significantly lower. The high-sensitivity tests are superior to the standard guaiac-based FOBT in detecting colorectal cancer and advanced lesions.

On a positive note, 93 percent of physicians reported using colonoscopy as a follow-up to a positive FOBT, as recommended in national guidelines.

Screening is recommended for adults aged 50 years and older.  Those with a family or personal history of colorectal polyps or cancer, or inflammatory bowel disease, should speak with their physicians about whether to begin screening at an earlier age. Annual FOBT is one of several screening options recommended by the U.S. Preventive Services Task Force and the joint guidelines issued by the American Cancer Society, the U.S.  Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. The other recommended screening tests are flexible sigmoidoscopy (every 5 years) and colonoscopy (every 10 years).  

Recent reports show that most primary care physicians recommend FOBT, either alone or in addition to colonoscopy, to screen for colorectal cancer. FOBT is preferred by a significant number of adults. Moreover, it is relatively inexpensive and easily accessible, and often the only screening test available to people with insufficient insurance coverage or those who live in areas with limited high-quality endoscopic services.

The researchers noted that educational efforts are needed to inform physicians of the recommended practices for screening with FOBT and to raise awareness of the newer high-sensitivity stool tests. The authors also encourage efforts to promote the use of provider tracking and reminder systems to enhance FOBT test completion and follow-up care.

Colorectal cancer is the second leading cause of cancer deaths in the United States, after lung cancer. In 2006, more than 139,000 new cases of colorectal cancer were diagnosed and more than 53,000 people died from this disease. Screening tests can find precancerous polyps so they can be removed before they have a chance to turn into cancer, thus preventing the disease. In addition, screening can detect cancers at an early stage when treatment can be very effective.

CDC's Colorectal Cancer Control Program funds 26 states and tribal organizations across the U.S. to increase rates of colorectal cancer screening among men and women 50 years of age and older through population-based approaches such as policy and health systems change, outreach, case management, and selective provision of direct screening services.

SOURCE Centers for Disease Control and Prevention