Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide and is the third most commonly diagnosed cancer in adults in the United States. While early detection can prevent over 90% of those deaths, more than one-third of the population eligible for screening are not up to date. Often, the discomfort and embarrassment of a colonoscopy is the hinderance.

But that may be changing.

A new study has found that a simple blood test can accurately detect CRC, potentially revolutionizing how this cancer is diagnosed.

The study, published in the journal Clinical Cancer Research, involved a blood test that measures the levels of a biomarker called methylation in circulating cell-free DNA (cfDNA). Methylation is a process that modifies DNA and is known to be involved in the development and progression of cancer.

The researchers analyzed blood samples from 620 individuals, including 167 with CRC, 253 with other gastrointestinal conditions, and 200 healthy controls. They found that the blood test accurately detected CRC with a sensitivity of 91.2% and a specificity of 88.7%.

This means the blood test correctly identified 91.2% of individuals with CRC and correctly excluded 88.7% of individuals without CRC. Better still, the blood test also detected early-stage CRC, which is typically more difficult to diagnose.

That early stage detection could mean far more lives saved.

“We undertook this study to prevent colorectal cancer-related deaths and sought to do this by addressing the need to improve compliance with CRC screening,” explained William Grady, MD, study author and gastroenterologist at Fred Hutchinson Cancer Center. “People tend to prefer blood-based screening tests over other types of screening tests, like colonoscopy and stool tests, so we set out to create such a test for CRC.”

The researchers suggest that the blood test could be used as a non-invasive screening tool for CRC, particularly for individuals at high risk of developing the disease. It could also be used to monitor patients with CRC for disease recurrence and response to treatment.

Further research is needed to validate these findings and to determine the optimal use of the blood test in clinical practice, but this is an exciting step in a healthier direction!

Everyone age 45-75 should get screened for colorectal cancer. Stool testing is suggested at least every 3 years, but a colonoscopy is still the “gold standard” for screening. If a colonoscopy is performed and no precancerous changes or abnormalities are found, it is generally recommended that they be repeated only every 10 years.

Not all people with colorectal cancer experience symptoms such as fatigue or changes in bowel habits. For this reason, it is critical to keep up on recommended screening. While the promise of a blood test will may make screening compliance higher in the future, individuals should get screened with whatever means are available as soon as a doctor recommends.

Half of the people given the option to undergo screening with a stool-based test or colonoscopy declined both.

Sources:

https://www.mayoclinic.org/diseases-conditions/colon-cancer/symptoms-causes/syc-20353669
https://www.nejm.org/doi/full/10.1056/NEJMoa2304714
https://www.unitypoint.org/news-and-articles/5-colon-cancer-symptoms-that-are-easy-to-overlook