New Colon Cancer Test Shows Promise
Jan. 30, 2002 -- Perfecting a simple, accurate, and noninvasive diagnostic test has been the elusive Holy Grail of colorectal cancer research. The best existing tests are highly invasive and widely perceived as uncomfortable or painful. As a result, many people who should be tested for colon cancer are not, and thousands of people die needlessly each year from the disease.
Now, researchers from Baltimore's Johns Hopkins University say they have developed a safe and reliable noninvasive test that can detect early colon cancers and precancerous polyps. The test involves the identification of a specific genetic marker in stool samples and may be clinically available within three years. Though it is not designed to replace invasive tests like colonoscopy or sigmoidoscopy, it could prove to be a valuable new screening tool.
"From a patient's point of view, this test is even simpler than a fecal occult blood test, because they only need to collect one sample instead of three," lead researcher Bert Vogelstein, MD, tells WebMD. "We hope this will be a good option for people at average risk who elect to have a noninvasive test, rather than an invasive one like colonoscopy or sigmoidoscopy."
The findings are the culmination of a decade of work by Vogelstein and Johns Hopkins colleagues. In the early 1990s, the researchers identified the adenomatous polyposis coli (APC) gene, and mutations in the gene were shown to be associated with molecular and cellular errors leading to tumor formation. The researchers have since developed a way to reliably detect the tumor marker in fecal DNA.
In the current study, published Jan. 31 in TheNew England Journal of Medicine, stool samples were analyzed from 28 people with early colon cancers, 18 people with premalignant polyps, and 28 people without disease. The test detected the genetic mutation in 61% of those with cancer, half of those with polyps, and none of the cancer-free controls.
The genetic marker test is not as reliable as colonoscopy -- the gold standard of colorectal cancer screening that has a sensitivity of 90%. The sensitivity of the APC test is comparable to sigmoidoscopy, Vogelstein says.