A novel test shows a difference in the Raman spectra of the blood plasma of people without colon cancer compared to those with precancerous or cancerous polyps. Credit: Haishan Zeng, BC Cancer Agency
It shows the simple fingerprint for cancerous growth and precancerous polyps. It may yield a cheaper and less invasive initial screening test for colon cancer that could complement colonoscopy, though further clinical trials will need to demonstrate the safety and effectiveness of the blood test before it is routinely used.
“This is a screening technology you can use on anybody,” said Haishan Zeng, BC Cancer Agency, who led the study. Current health guidelines say that adults should have a colonoscopy every 10 years beginning age 50 – and sooner or more frequently if other risk factors exist – but CDC statistics say that only 65% of American adults actually follow these guidelines.
That’s why many researchers are searching for less invasive alternatives to the colonoscopy that could induce encourage more people to get tested.
BC Cancer Agency and University of British Columbia have identified differences in the blood of people with precancerous polyps compared to people without such polyps. The team collected blood plasma samples from 3 groups: 23 who had adenomatous (precancerous) polyps, 21 who had verified colon cancer, and 25 healthy volunteers. They mixed each plasma sample with silver nanoparticles and then analyzed the mixtures with surface-enhanced Raman spectroscopy (SERS) which uses a laser to excite the sample and measure shifts in the vibrational energy of its molecules, which can provide insight into the sample’s molecular structure. In surface-enhanced Raman spectroscopy, nanoparticles are added to boost the signal.
Although the team identified significant spectral differences between the blood samples, they haven’t yet determined the exact biomolecular sources for these differences. “We are planning new research to identify these responsible molecules,” said Zeng.
A blood test for colon cancer will never replace colonoscopy: once polyps are identified, a colonoscopy is still the best way to figure out where they’re located so that they can be removed. However, a blood test could be used as a first line of defense to identify patients with warning signs of cancer; these high-risk patients could then be referred for a colonoscopy. Â http://www.osa.org/en-us/about_osa/newsroom/news_releases/2015/new_blood_test_for_colon_cancer_improves_colonosco/
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