New Colon Cancer Screening Test in the Works
Consumer-Friendly Test Under Study; DNA Findings Help Predict Risk
WebMD News Archive
DNA Clues to Colon Cancer
In other research, Lisa Boardman, MD, an associate professor of medicine at Mayo Clinic, wanted to find out if people who develop colon cancer at a younger age than usual are biologically older. (The median age of colon cancer diagnosis is 70, according to the National Cancer Institute.)
To determine biological age, Boardman's team focused on telomeres -- small strips of DNA that cover the end of chromosomes. "They're similar to the protective cap on shoelaces," Boardman says. "Telomeres are a biologic time clock. As we age, our telomeres will become shorter."
She took DNA from the blood of 772 patients diagnosed with colon cancer, all under 60 when diagnosed. She compared the group's telomere lengths to those of 1,660 age-matched healthy patients.
She didn't find what she expected: "We found that longer telomere length was associated with colorectal cancer in people under age 50."
But in those over age 50, those with the longest telomeres had the lowest chance of developing colorectal cancer, she found.
The implications, she says, may be that there are different types of colorectal cancer in younger patients; this in turn may drive different and more effective treatments.
Colon Cancer Advances: Perspectives
“Both findings are interesting,” says Anil Rustgi, MD, the T. Grier Miller professor of medicine and chief of gastroenterology at the University of Pennsylvania School of Medicine, and a program chairman for the conference.
He cautions that both the findings about telomeres and the results of the stool test study are in early stages. But both areas fill a need, he tells WebMD. “Very broadly speaking, there is a need to develop biomarkers, whether blood based or stool based, or both, in order to identify patients who might be at increased risk for colon cancer.”
The detection rates for the new test appear promising, "but this was a very preliminary study that utilized samples from individuals who were known to have colon polyps or cancer,” says Durado D. Brooks, MD, director of prostate and colorectal cancers for the American Cancer Society, who reviewed the findings. “The performance may decrease considerably when the test is used in a large population of healthy individuals, where only a small number of polyps or cancers may be present."
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.