The American Cancer Society has released its first major update to colorectal cancer screening guidelines since 2018. The revision 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 several factors, including diet and environmental exposures, to the increase in early-onset cases. Here are five key points from the updated guidelines.
Blood tests get cautious response
Blood-based tests, also called liquid biopsies, have been promoted as a convenient alternative to stool tests and colonoscopies. But the American Cancer Society advises against using them as a first-choice screening option.
According to the guidelines, blood-based tests should only be offered to people who decline or have not completed a preferred screening test. The main issue is sensitivity. These tests showed lower sensitivity for advanced precancerous lesions and stage I cancers compared with stool-based tests.
The guidelines note that about 80 percent of the long-term benefit from colorectal cancer screening comes from detecting and removing precancerous lesions. Blood-based tests have very low sensitivity for these lesions, around 13 percent in two large studies.
Specificity also declines with age. In the ECLIPSE and PREEMPT CRC studies, specificity dropped from above 90 percent in participants under 55 to about 80 percent in those 70 and older. This means older adults face more false positives and greater risks from follow-up colonoscopy.
The American Cancer Society acknowledges that blood-based tests have value for people who would otherwise go unscreened. For them, a blood test is better than nothing.
Two new stool tests added to preferred list
Two newly approved stool tests have been added to the preferred screening options list.
ColoSense is a multitarget stool test that uses an algorithm combining eight RNA biomarkers, a fecal immunochemical test, and self-reported smoking status. In the CRC-PREVENT validation study, it showed 94.4 percent sensitivity for colorectal cancer, 100 percent sensitivity for stage I disease, and 45.9 percent sensitivity for advanced adenoma. It received FDA approval in 2024.
Cologuard Plus is a next-generation multitarget stool DNA test. It is an updated version of the original Cologuard test with a revised marker set to improve specificity while maintaining high sensitivity. In the BLUE-C study, it showed 93.9 percent sensitivity for colorectal cancer and 43.4 percent sensitivity for advanced precancerous lesions. It also received FDA approval in 2024.
Both tests are done every three years. They join a short list of recommended stool-based screening options that includes annual high-sensitivity stool blood tests and an older DNA stool test. Modeling studies suggest all of these options offer a similar ability to reduce colorectal cancer cases and deaths.
Medicare and Medicaid coverage for ColoSense is still pending as of this guideline update, which could affect access for some patients.
Positive test requires follow-up colonoscopy
This applies to every non-colonoscopy screening test, stool-based and blood-based alike. The guidelines state clearly that a positive result requires timely follow-up with colonoscopy, preferably within six months.
Follow-up with a repeat stool or blood test is not acceptable after a positive result. The guidelines note that self-reported screening data are misleading in part because people who test positive on a non-colonoscopy test do not get their follow-up colonoscopies.
Data from one randomized trial cited in the guidelines showed that only 50 percent of participants with a positive blood-based test completed a follow-up colonoscopy within six months. That compares with 70 percent of those with a positive fecal test.
Age 45 screening start remains
In 2018, the American Cancer Society lowered the recommended screening start age from 50 to 45 for average-risk adults. That recommendation is reaffirmed in this update.
Colorectal cancer incidence increased in adults under 50 at a rate of 3 percent per year between 2013 and 2022. Among U.S. adults under 50, colorectal cancer is now the leading cause of cancer death among men and the second leading cause among women.
Despite the 2018 recommendation, uptake among the newly eligible age group remains low. In 2023, only 37 percent of adults aged 45 to 49 reported being up to date with recommended screening. Screening rates were lower among Hispanic, Asian, and American Indian or Alaska Native individuals compared with White and Black individuals.
Disparities remain a concern
The guidelines highlight several differences in colorectal cancer burden by racial and ethnic group. Age-adjusted incidence rates are estimated to be 11 percent higher among Black individuals, and their mortality rates are about 40 percent higher than White individuals.
American Indian and Alaska Native populations have incidence rates 48 percent higher and mortality rates about 44 percent higher than White populations. Alaska Native people specifically have more than double the incidence and mortality rates observed among White populations.
These disparities exist alongside gaps in screening access. Lack of insurance and lower socioeconomic status are associated with lower screening prevalence. The guidelines note that the anticipated high cost of newer tests, including blood-based tests, ColoSense, and Cologuard Plus, will be a barrier for uninsured and underinsured populations.
Annual high-sensitivity stool blood tests and older DNA stool tests remain the low-cost options among recommended tests. Modifiable lifestyle factors like alcohol consumption also contribute to colorectal cancer risk and are worth addressing alongside screening efforts.
