The American Cancer Society has released its first major update to colorectal cancer screening guidelines since 2018. The update follows the approval of new molecular-based screening tests by federal regulators and ongoing concerns about rising cancer rates among younger adults. Researchers have linked diet and environmental factors to the increase in early-onset cases. The new guidance includes several key changes.
Blood tests are not a top choice
Blood-based tests, also called liquid biopsies, are not recommended as a preferred screening option at this time, according to the updated guidelines. These tests should only be offered to people who have not completed or who decline other screening methods. The main issue is sensitivity. Blood tests showed lower sensitivity for advanced precancerous lesions and stage I cancers compared to stool-based tests. The goal of colorectal cancer screening is to prevent cancer by finding and removing precancerous growths. One modeling study estimated that 80% of the long-term benefit from screening comes from detecting these lesions. Blood tests have very low sensitivity for advanced precancerous lesions, around 13% in two large studies. Specificity also declines with age, dropping from above 90% in people under 55 to about 80% in those 70 and older, leading to more false positives in older adults. The guidelines note that blood tests still have value for people who would otherwise not get screened.
Two new stool tests are now preferred
Two newly approved stool tests have been added to the list of preferred screening options. The first is ColoSense, a multitarget stool test that uses eight RNA biomarkers, a fecal immunochemical test, and self-reported smoking status. In a validation study, it showed 94.4% sensitivity for colorectal cancer, 100% sensitivity for stage I disease, and 45.9% sensitivity for advanced adenoma. It received FDA approval in 2024. The second is Cologuard Plus, a next-generation multitarget stool DNA test. In a study, it showed 93.9% sensitivity for colorectal cancer and 43.4% sensitivity for advanced precancerous lesions, with improved specificity compared to the original test. It also received FDA approval in 2024. Both tests are done every three years. They join other recommended stool-based options, including annual high-sensitivity stool blood tests and an older DNA stool test. Medicare and Medicaid coverage for ColoSense is still pending.
A positive test requires a follow-up colonoscopy
Every non-colonoscopy screening test, whether stool-based or blood-based, requires a follow-up colonoscopy if the result is positive. The guidelines state this should happen within six months. A repeat stool or blood test is not acceptable. Real-world data show this is a problem. One study cited in the guidelines found that only 50% of people with a positive blood test completed a follow-up colonoscopy within six months, compared to 70% of those with a positive fecal test. A positive screening test is the start of the process, not the end.
Screening should start at age 45
The 2018 recommendation to start screening at age 45 for average-risk adults is reaffirmed. Colorectal cancer incidence increased in adults under 50 at a rate of 3% per year between 2013 and 2022. Among U.S. adults under 50, it is the leading cause of cancer death in men and the second leading cause in women. Despite the recommendation, only 37% of adults aged 45 to 49 reported being up to date with screening in 2023. Screening rates were lower among Hispanic, Asian, and American Indian or Alaska Native individuals compared to White and Black individuals.
Disparities remain a serious concern
The guidelines highlight stark differences in colorectal cancer burden by race and ethnicity. Age-adjusted incidence rates are 11% higher among Black individuals, and mortality rates are about 40% higher than White individuals. Among American Indian and Alaska Native populations, incidence rates are 48% higher and mortality rates are about 44% higher. Alaska Native people have more than double the incidence and mortality rates observed in White populations. These disparities exist alongside gaps in screening access. Lack of insurance and lower socioeconomic status are linked to lower screening rates. The high cost of newer tests, including blood-based tests and the new stool tests, will be a barrier for uninsured and underinsured people. Annual high-sensitivity stool blood tests and older DNA stool tests remain the low-cost options. Modifiable factors like alcohol consumption also contribute to colorectal cancer risk.
