A Simple Blood Test Catches Polyps, Early-Stage Colorectal Cancer

• A new blood test shows promise in catching precancerous polyps and early stage colorectal cancer. 
• In trials, the DENEB blood test detected 92% of stage I–III colorectal cancers and 81% of high risk polyps.
• It is a noninvasive and experimental test. More research is needed before it can be recommended for routine screening.
• Colonoscopy and stool-based tests remain the gold standard for colorectal cancer screening.

A new experimental blood test, DENEB, could offer a simpler, noninvasive way to detect early stage colorectal cancer and precancerous lesions (polyps). 

The multicenter diagnostic study of this blood test, published in The Lancet Gastroenterology & Hepatology on August 10, found that the DENEB test detected 92% of stages I, II, and III colorectal cancers, and 81% of advanced adenomas (precancerous polyps).

This is an important development because colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer death in the United States, and traditional screening methods like colonoscopy can be invasive and inconvenient.

DENEB blood test may detect 81% of pre-cancerous polyps

There are blood tests currently available for colorectal cancer screening. However, what sets the DENEB test apart is its ability to detect precancerous polyps. Removing these polyps can help prevent cancer from forming. 

Ajay Goel, PhD, Professor and Founding Chair, Department of Molecular Diagnostics and Experimental Therapeutics, Beckman Research Institute of City of Hope, and co-author of the study, told Healthline that the most important aspect of their findings is that they detected 81% of these precancerous polyps. 

“Many blood-based screening tests are very good at finding cancer, but have struggled to detect these precursor lesions,” he said. 

The researchers tested more than 1,500 adults who were participating in colonoscopy screening programs in China, Japan, and Spain. 

In addition to detecting precancerous polyps, the DENEB blood test detected 91% of colorectal cancers overall and 92% of stage I, II, and III cancers. 

“If these findings are confirmed in prospective screening studies, a blood test like DENEB could potentially help us move from simply finding colorectal cancer earlier to actually preventing some cancers from developing,” said Goel. 

How does DENEB compare to current screening methods? 

The current colorectal cancer screening guidelines from the American Cancer Society (ACS) include colonoscopy, which is still the gold standard for screening, and stool-based tests, such as the fecal immunochemical test (FIT). 

Blood tests, such as Shield, are also available. However, they are not the preferred screening method. The ACS states that they should only be used when people are unwilling to undergo a visual or stool-based test. 

Currently, the Shield test is the only one approved by the Food and Drug Administration (FDA). It is also only 13% effective in detecting precancerous polyps, though it may be around 83% effective in detecting colorectal cancer. 

The DENEB test is more sensitive than Shield, especially in detecting precancerous polyps. 

“The larger opportunity is to make screening easier and more accessible. A blood test could be incorporated into a routine medical visit to help identify people who should undergo [a] colonoscopy, particularly those who might otherwise avoid traditional screening,” said Goel. 

Ketan Thanki, MD, board certified colorectal surgeon with the MemorialCare Todd Cancer Institute at Long Beach Medical Center in Long Beach, CA, who wasn’t involved in the study, told Healthline that if these results can be reproduced, clinicians will be one step closer to using blood-based tests widely for colorectal cancer screening and being able to avoid routine colonoscopies for most average-risk people. 

This blood test is also not meant to replace a colonoscopy. Goel noted that colonoscopy remains the definitive test because it can both find and remove precancerous lesions. The potential value of a blood test lies in bringing more people into the screening pathway. 

Why colorectal cancer screening matters

Colorectal cancer screenings are important because the rates of these types of cancers are on the rise, especially among those under 50. It is also now the number one cause of cancer-related deaths in this age group in the United States. 

Colorectal cancer is any cancer that develops in the colon or rectum. 

Regular screenings are also important because early stage colorectal cancers do not typically cause symptoms. 

Early detection and removal of precancerous polyps may help prevent cancer from developing. Also, if cancer is present, early diagnosis makes treatment easier and outcomes better. 

According to a study published in JAMA Network on August 20, people who undergo colorectal cancer screening have up to a 43% lower risk of dying from the disease. This is based on 14 years of follow-up data from the Stockholm–Gotland screening program.

While more research is needed, these results show that colorectal cancer screening can improve the outcomes for people with the disease.

“As early onset colorectal cancers become more prevalent and affect people who seemingly do not have obvious risk factors for developing cancer, we need to start screening people at younger ages,” said Thanki.  

“We are therefore in desperate need of cheaper, more accessible screening tests. Blood-based and stool-based screening tests answer this need while freeing up endoscopists to focus on high risk patients and those who have abnormal blood or stool tests and need more work-up. Every study like this that comes out is progress,” he said.