Stool tests that look for blood can detect colon cancer consistently when done annually and are still effective even after succeeding years of testing, according to researchers. The results of their work suggest that stool tests could be a reasonable alternative to colonoscopy, the current gold standard in screening for colon cancer.
In a study published in the journal Annals of Internal Medicine, Dr. Douglas Corley and colleagues explored how effective fecal immunochemical tests are by examining the results of annual fecal blood tests on almost 325,000 patients from Kaiser Permanente over the course of four years.
Precancerous polyps or colon tumors begin releasing blood into a patient's stool only when they are large. As such, when they are detected and removed within the first year of screening, doctors are concerned that cancer detection might drop in the next years.
Based on their samples, the researchers found that 84.5 percent of the participants diagnosed with the disease had fecal blood test results indicative of colon cancer. They were not surprised by this, however, as cancers that have been there for a while are generally easier to detect.
However, in the second to the fourth years of the study, the researchers found that fecal blood tests were still 73 to 78 percent effective in detecting colon cancer, meaning stool tests still had the ability to pick up on tumors as they grew big enough to be detected.
Does this mean stool tests can take the place of colonoscopies?
Not necessarily, according to the researchers, as they still recognize that colonoscopy has the advantage of needing to be done just once every 10 years and is almost 100 percent effective in detecting precancerous polyps and cancers.
With stool tests found to be effective, they could at least be considered as another screening choice for those who don't want to undergo colonoscopies. Cost shouldn't be a deciding factor between the two because the Affordable Care Act stipulates that colon cancer screenings be covered by insurance companies.
To be clear, the study was carried out on standard fecal blood tests and not Cologuard, which combines fecal blood tests with a genetic scan to look for DNA biomarkers associated with colon cancer.
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