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Colon cancer spotted by blood test

CNN News Wire | 6/7/2013, 10:46 a.m.

For the field of cancer research, a reliable blood test for colorectal cancer would be a revelation.

Currently, the condition is diagnosed through stool blood tests and uncomfortable colonoscopies, but the dream is to be able to find genetic markers predictive of such cancers in order to intervene early or follow patients in their treatment.

A study published Friday in the Journal of Molecular Diagnostics suggests that a blood test for colon cancer could be on the horizon. But the research is still preliminary and the test is not currently recommended as a screening tool, said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.

The lifetime risk of developing colorectal cancer is 1 in 20, and men are slightly more likely to get it than women, according to the American Cancer Society. In 2013, it is expected to cause more than 50,000 deaths.

The study
Researchers at Genomictree, Inc., and the Yonsei University College of Medicine in Seoul, South Korea, first went on a "search mission" to find genes that could be related to colorectal cancer tissue, Lichtenfeld said. They compared tumor tissue samples from patients to non-tumor tissue, and identified candidate genes that could be markers for colon cancer. They focused on one for further investigation, a marker called SDC2.

Then, scientists took blood samples from 12 colon cancer patients with various stages of cancer, to look for that gene. They found that this gene was present, and could be detected, in the patients' blood. In these patients, the gene was predictive for colon cancer.

Bigger picture
The ultimate goal of this line of research is to find a blood test that would either find cancer early or help doctors follow patients in their treatment to see how it's working, Lichtenfeld said.

This research shows that this particular gene may be a marker that could be useful in either following colon cancer patients, or potentially defining colon cancer early and saving lives, he said.

Ultimately, however, doctors want to be able to identify a lesion before it becomes cancerous, Lichtenfeld said. The authors of this study not claim that this blood test will do that.

It's unknown whether this particular test would find colon cancer early enough to save lives or prevent people from developing the disease, Lichtenfeld said. More research needs to be done.

Other candidates
This isn't the only potential marker for colon cancer that a blood test could pick up. There are other genes that other research groups are looking at, too.

Study authors wrote that their findings are similar to those of the SEPT9 test for colorectal cancer.

SEPT9 is a gene that has also been correlated with the condition. A 2011 study in the journal BMC Medicine showed the potential for that gene to serve as a marker in a blood test for colorectal cancer -- but this research is not definitive either.

"No reputable organization is recommending that either of these tests be used as screening test for colon cancer," Lichtenfeld said.

The SEPT9 test is being marketed with claims that it could replace a colonoscopy, but the American Cancer Society does not recommend it at this time, Lichtenfeld said.

Elizabeth Landau | CNN