May 30, 2002 -- A new, non-invasive test may take some of the discomfort and fear out of screening for colorectal cancer. British researchers have developed a new fecal test that detects cancerous cells in stool samples.
Colorectal cancers cause more than 500,000 deaths worldwide each year. Experts say many of those deaths could be avoided through early detection and treatment of the disease.
Some of the most effective screening methods currently available are colonoscopy and sigmoidoscopy, but these tests are invasive -- they require inserting a tube inside the rectum. Fecal occult blood testing is also used in many cases, but recent studies have suggested that the at-home test isn't as accurate as the more invasive tests.
Researchers say this new fecal test may be an inexpensive and more reliable testing option with minimal discomfort to the patient. In their study, Nicholas Coleman and colleagues from the MRC Cancer Cell Unit in Cambridge, England, evaluated a stool-based test that can identify a specific protein known as MCM2 that is present in cancerous colorectal cells but not in healthy cells.
Researchers were able to detect the MCM2 cells in stool samples from 37 of 40 patients known to have colorectal cancer. None of the cells were found in tests performed on samples from 25 healthy subjects.
"These findings suggest that the detection of MCM2 expression in [cells] retrieved from the fecal surface might be of value in the non-invasive diagnosis of malignant colorectal disease," write the authors, "our approach might ultimately prove suitable for population screening, either alone or in combination with other tests."
The results of the study are detailed in a research letter published in the June 1 issue of The Lancet.
The American Cancer Society currently recommends the following guidelines for colorectal cancer screening. Beginning at age 50, both men and women should follow one of these five screening options:
- Yearly fecal occult blood test
- Flexible sigmoidoscopy every five years
- Yearly fecal occult blood test plus sigmoidoscopy every five years
- Double-contrast barium enema every five years
- Colonoscopy every 10 years
People who have a family history of colorectal cancers should discuss earlier screening options with their doctor.