An investigational stool DNA test may be effective as a screening tool for colorectal cancer. These findings were recently presented at the American Association for Cancer Research special conference on Colorectal Cancer: Biology to Therapy, in Philadelphia on October 27-30, 2010.
Cancers of the colon and rectum, sometimes referred to together as colorectal cancer, often begin with the development of an adenomatous polyp, which is a small tumor that grows in the colon. These polyps often take 10 to 15 years to transform into cancer. Because this development phase is so long, screening and early detection can play a crucial role in the prevention of colorectal cancer, as detection and removal of the polyps can prevent the development of the disease. When detected early, colorectal cancer is a highly curable disease. However, once the cancer has spread to distant and/or several sites in the body, cure rates remain low. Colorectal cancer is currently the second leading cause of cancer deaths in the United States. Thus, screening measures to detect polyps or colorectal cancer early may significantly reduce the number of deaths caused by colorectal cancer annually.
Screening procedures for colorectal cancer include the fecal occult blood test (FOBT), sigmoidoscopy, colonoscopy, and the double-contrast barium enema; however, the potential for earlier detection and higher cure rates may increase with the advent of more refined screening techniques. Due to the cost and invasive nature of some screening procedures, individuals are sometimes resistant to colorectal cancer screening. For example, fewer than 30% of eligible individuals have had a screening test for colorectal cancer compared with 70 to 80% of women undergoing screening for breast cancer and cervical cancer. Consequently, much research is aimed at developing patient-friendly but effective screening procedures.
A newer type of test that’s showing promise is a stool DNA test. Cells from the colon and rectum are shed in the stool, and stool DNA tests look for DNA changes that are characteristic of polyps or cancer. If the test suggests that polyps or cancer may be present, patients undergo colonoscopy for further evaluation.
In the current study, stool samples from 678 individuals were tested with an investigational DNA test.
These results are promising. Additional studies are planned to determine the role of this strategy in colorectal cancer screening.