Researchers have developed a new home blood test for colorectal cancer that is as accurate as current home tests using stool samples. This new test is hoped to encourage more people to get tested for colorectal cancer early, as early detection is crucial for successful treatment. While colonoscopy is still considered the most accurate method of detection, the new home-based blood test is a more convenient option for those who dislike the home stool test. Both tests are about 83 percent accurate, according to a study published in the New England Journal of Medicine.
The study, called ECLIPSE, compared colonoscopies to the Guardant’s Shield blood test, which detects colorectal cancer signals in blood DNA shed by tumors, known as circulating tumor DNA (ctDNA). The study found that 83% of participants with colorectal cancer confirmed by a colonoscopy had a positive blood test for ctDNA, while 17% had a negative test. The test is most sensitive for colorectal cancers, including early stage cancers, but less sensitive for advanced precancerous lesions. While younger people are increasingly being diagnosed with colorectal cancer, colorectal cancer death rates have declined in older adults.
Colorectal cancer is the second most common cause of cancer deaths in adults in the United States, with 53,000 people expected to die from the disease in 2024. Rates among people under 55 have been increasing by about 1% per year since the mid-2000s. Current guidelines recommend that people at average risk should begin screening at age 45. Having a blood-based test for routine doctor’s visits could help more people be screened for colorectal cancer and potentially detect and prevent the disease early.
Dr. Jeremy Kortmansky, clinical director of the GI Medical Oncology Division at Yale Cancer Center, explained that a higher accuracy rate in home-based tests is difficult to achieve because the sensitivity of home-based stool tests correlates with the size of the polyp or cancer. The volume of stool required for the test might also be a barrier, as well as the need for a prescription to obtain the test. Dr. Anton Bilchik, a surgical oncologist, suggested that a disruption in the balance of the microbiome could be important in the development of colon cancer. A study found that a subtype of the bacteria Fusobacterium may be responsible for tumor growth, providing potential targets for future therapies.
Symptoms of colon cancer include abdominal pain or cramping, change in stool habits, blood in the stool, weight loss, and low iron levels in the blood. Screening is essential to detect cancers or pre-cancers early when they are not symptomatic and are highly curable. The new blood-based test for colorectal cancer offers a more convenient option for screening, which could help increase the number of people getting tested. More research is needed to explore the use of bacteria in preventing colorectal cancer and to develop targeted therapies for the disease.
