Researchers developing blood-based colon cancer test

Scientists at UW-Madison have discovered four new blood-based markers for colon cancer, which they say could lead to a new blood test for the cancer.

A study published this week in the scientific journal Proceedings of the National Academy of Sciences describes these protein markers, which are associated with pre-cancerous forms of colon cancer that pose particular danger.

“This study is the first peek at the possibility that there will be blood markers for a minimally invasive procedure that can reduce over-diagnosis,” said senior author Bill Dove, professor of oncology and genetics with the Carbone Cancer Center at UW-Madison.

Though non-invasive options for colon cancer screening do exist — such as Madison-based Exact Sciences’ Cologuard test, which relies on stool samples — the authors of the study say a new blood-based test could help improve screening rates while driving down the rate of overtreatment.

“We believe success may come from combining multiple strategies that are statistically independent from each other,” Dove said.

The vast majority of people diagnosed with colon cancer are over 50, according to the Mayo Clinic. This type of cancer is much easier to treat when it’s caught earlier, but compliance with screening recommendations is relatively low, due in part to the invasive nature of colonoscopies.

When growths on the colon known as polyps are found during this procedure, doctors will remove the growths and determine if they are cancerous or benign.

Another screening option called computed tomographic colonography creates an image of the colon without requiring an invasive procedure — at least at first. If the image shows a potential issue, then patients often have to undergo a follow-up colonoscopy and polyp removal. In some less dangerous cases, doctors recommend a monitoring approach only.

In this new study, researchers looked for proteins that were elevated in the blood of patients with cancerous or growing polyps but not elevated in patients with no polyps or whose polyps weren’t growing.

They studied blood samples from 90 colonoscopy patients with varying levels of risk and 31 computed tomographic colonography patients who were monitored but didn’t have their polyps removed.

The scientists started with a list of 19 proteins that had previously been linked to colon cancer in rodent models. They used a scanning technique called mass spectrometry to measure levels of proteins in patients’ blood and compared those blood markers to the patients’ colonoscopy results.

They found four proteins that are associated with early colon cancer in the study patients.

“There’s good evidence they’re being conserved in early disease in humans,” Dove said. “We didn’t expect we could find blood markers for such small, early, pre-malignant polyps in humans, but we did.”

Funding for the project came from the National Institutes of Health, the National Cancer Institute and the Wisconsin Alumni Research Foundation.

See more from the study:

–By Alex Moe