With 83% accuracy in detecting colon cancer, a new blood test could boost screening.
A new analysis for detecting colon cancer – Photo Archive
Scientists have developed a blood test that is 83% accurate in diagnosing colorectal cancer, offering an alternative to current stool tests. The findings of the new study were recently published in the New England Journal of Medicine.
“The results of the study are a promising step towards the development of more convenient tools to detect colorectal cancer in time, while making it easier to treat. The test, which has an accuracy rate for detecting colon cancer similar to that of stool tests used for early cancer detection, could offer an alternative for patients who might otherwise decline current screening options“, said William M Grady, gastroenterologist at the Fred Hutchinson Cancer Center in Seattle, USA, quoted by Euronews.
This type of cancer is causing more and more deaths among people aged 25 to 49 in the European Union and Great Britain, another study by the University of Milan shows.
Doctors can make this diagnosis with stool tests that detect blood or damaged DNA in the samples, or with colonoscopy or sigmoidoscopy (a medical procedure to examine the lower part of the large intestine, called the sigmoid colon).
Considered “the gold standard” to screen for this condition, colonoscopy is an invasive procedure. CT colonography, also called virtual colonoscopy, uses X-rays to detect signs of cancer.
Sensitivity in detecting cancers in early stages
Instead, the new test detects circulating tumor DNA (ctDNA), DNA that is shed by cancer cells, in the blood.
To test the effectiveness of the analysis, 8,000 participants between the ages of 45 and 84 who also underwent a standard colonoscopy took part in the study, and the researchers compared the results.
In 83.1% of cases, the blood test confirmed the diagnosis, while for a percentage of 16.9% of patients, the result was negative with the ctDNA technique, but positive with the help of colonoscopy.
Moreover, the test showed higher sensitivity in detecting colorectal cancers, even in early stages, but showed lower sensitivity in identifying advanced precancerous lesions that have the potential to turn into cancer over time.
Second place in mortality in the EU
Colorectal cancer is the second most common in the EU, with a rate of 12.7% of new cancer diagnoses in 2020, and the second leading cause of cancer deaths.
Screening is needed to prevent this condition, but in more than half of EU countries, the majority of people aged 50 to 74 have never been screened for colorectal cancer in 2021, according to Eurostat. If in northern Europe countries such as Finland, the Netherlands or Denmark had screening rates of over 60%, Serbia, Montenegro and Hungary had rates below 10%, according to the cited source.
Moreover, Eurostat data show that over 90% of Romanian respondents stated that they had never been screened for colorectal cancer.
“Getting people tested for cancer works best when we give them screening options and then let them choose what's best for them” said William M. Grady.
Early diagnosis increases survival rates. Screening tests can find precancerous polyps, allowing them to be removed before they turn into cancer, according to the US Centers for Disease Control and Prevention (CDC). Specifically, an early diagnosis leads to a 90 percent survival rate. But when the cancer metastasizes, or migrates, to other parts of the body, that rate drops to 25 percent.
“We continue to see younger people getting colorectal cancer and it is now the third most common cancer for people under the age of 50. Having a blood-based test for people to take during routine doctor visits could be an opportunity to help more people get diagnosed“, the US gastroenterologist added.
