Apr 27, 2010 11:44 PM
April 27, 2010 -- It won't happen anytime soon, but researchers say they may be on the path to developing a simple urine test that could both diagnose colorectal cancer and follow its progress.
Using a relatively new science known as metabolomics, researchers identified unique chemical patterns in urine samples from cancer patients that could help them develop just such a test.
Metabolomics is the study of small molecule metabolites, which are the by-products of metabolism -- the chemical process necessary for life in which the body breaks down or synthesizes organic matter.
The idea is that people have unique metabolic profiles that are altered by diseases like cancer, study researcher Wei Jia, PhD, of the University of North Carolina at Greensboro tells WebMD.
Just as a fingerprint is used to identify a person, a specific metabolite pattern may prove useful for detecting cancer or assessing whether treatments are working.
In the newly published study, Jia and colleagues searched for more than 500 metabolites in urine samples from 60 patients with colon cancer and 63 people without the disease.
They identified more than a dozen substances that were altered in the patients, including significant disturbances in the expression of tricarboxylic acid (TCA), which regulates energy metabolism, and elevated levels of the amino acid tryptophan.
Some of the alterations were also seen in rats with colon cancer.
The research appears in the latest issue of the American Chemical Society's Journal of Proteome Research.
Jia says further studies could determine if the metabolite expression differs among patients with colorectal cancer at different stages of the disease.
If this is the case, urine analysis could prove useful for assessing how well patients are responding to treatments, he says.
American Cancer Society spokesman Michael H. Melner, PhD, says such a test is, at best, many years away if it happens at all.
Melner serves as scientific program director for molecular genetics and biochemistry for the American Cancer Society.
"This is an interesting first step, but this research is very preliminary," he tells WebMD. "I would hesitate to say anything about the potential for a urine test to detect colorectal cancer based on this research."
Melner says there is much excitement about metabolomics within the cancer research community.
"Many different groups are utilizing this technique to explore altered metabolism within tumor cells," he says.
He cites research from the University of Michigan in which metabolomics was used to identify a possible biomarker for prostate cancer progression.
The metabolite sarcosine was not present at all in the urine of people without prostate cancer. Levels tended to be low in patients with less aggressive disease and high in those with advanced cancer.
Another research team from St. Louis' Washington University School of Medicine recently identified protein biomarkers for kidney cancer that could one day lead to a urine test for that disease.
Lead researcher Evan D. Kharasch, MD, PhD, says kidney cancer patients expressed high levels of two proteins -- AQP1 and ADFP.
"Levels were elevated 10- to 100-fold compared to people who did not have kidney cancer," Kharasch tells WebMD,
But this research is also very early, and it is not yet clear if the proteins are also elevated in people with other kidney diseases.