Noninvasive Stool Test Effectively Detects Colon Cancer

The noninvasive immunochemical fecal occult blood test (iFOBT) is highly effective at screening for colon cancer, according to a recent study published in the Canadian Medical Association Journal (CMAJ). The test examines the stool for hidden blood, which could come from anywhere in the gastrointestinal (GI) tract, and possibly indicates a colon tumor or precancerous growths known as polyps. The iFOBT is considered to have a greater sensitivity than the standard FOBT. If GI bleeding is detected, a follow-up colonoscopy is used to search for the origin of the blood.

In the iFOBT study in CMAJ, researchers from Taiwan recruited nearly 2800 individuals to undergo iFOBT, blood tests, colonoscopy, and an upper GI tract endoscopy. The iFOBT correctly detected almost 90% of colorectal cancers, adenomas and significant lower GI lesions. The study also demonstrated that the iFOBT was ineffective at detecting upper GI tract diseases, such as esophageal or gastric cancers.

Nurse Perspective

Laura Metcalfe, MSN, RN, APN, C, AOCNS John Theurer Cancer Center, Hackensack, NJ

Colorectal cancer is the third most common cancer and the second leading cause of cancer deaths in the United States. An effective way to reduce mortality from colorectal cancer is to screen for it and its precursor, the adenoma. Unfortunately, in the United States, colorectal cancer screening is underused. Various factors contribute to this underuse, including patient factors such as lack of awareness regarding screening, lack of insurance coverage, and fear of undergoing colonoscopy.

Colonoscopy still remains the gold standard and is recommended for individuals aged ≥50 years, assuming no increased risk factors. Patients with increased risk factors for colon cancer (eg, family history, history of inflammatory bowel disease, history of colonic polyps, and/or inherited genetic abnormality) require screening earlier than age 50 with colonoscopy. Colonoscopy not only detects colon cancers, but can remove precancerous polyps as well.

Studies have shown that patient preferences for colorectal cancer screening tests vary, and many patients prefer the fecal occult blood test (FOBT) over more invasive tests (ie, sigmoidoscopy and colonoscopy). Given this information, the lower cost of FOBT compared with other screening methods, and the results of this study, it would seem prudent to utilize FOBT for those patients who are either unwilling or unable to undergo colonoscopy as screening. Any positive test result would then require colonoscopy, and patients might be more willing to undergo colonoscopy upon receiving a positive FOBT. Of course, FOBT will not detect adenomas (precancerous polyps); however, a new DNA stool test is being studied that could improve the detection of cancers and precancerous polyps.

Therefore, FOBT may help increase colorectal cancer screening due to its non-invasiveness and low cost compared to alternative methods. Increased screening will lead to earlier detection, which would help reduce the number of colorectal cancer deaths. Any means of achieving that goal should be employed.

Reference

Chiang TH, Lee YC, Tu CH, et al. Performance of the immunochemical fecal occult blood test in predicting lesions in the lower gastrointestinal tract [published online ahead of print August 2, 2011]. CMAJ. doi: 10.1503/cmaj.101248.