A RECENT study from Stanford Medicine highlights both promise and caution surrounding newly approved blood tests for colorectal cancer (CRC) screening.
These tests, which detect cancer DNA in the bloodstream, offer an alternative to traditional colonoscopies and stool-based tests, requiring only a simple blood draw instead of the invasive, preparation-intensive procedures currently available. However, while blood tests could increase screening rates among those who avoid other methods, researchers warn that relying solely on these new tests could lead to higher CRC death rates.
Led by Uri Ladabaum, Professor of Gastroenterology at Stanford University School of Medicine, California, USA, the study analysed the efficacy of blood tests compared to colonoscopies and stool tests in identifying early-stage CRC and precancerous polyps. The study revealed that while blood tests might appeal to individuals resistant to standard screening, they fall short in accuracy and early detection power. Specifically, modelling data suggested that among 100,000 average-risk adults screened, those using colonoscopies every 10 years would see significantly fewer cancer cases and deaths than those using blood tests every 3 years.
The U.S. Preventive Services Task Force currently recommends that adults between 45–75 years undergo routine CRC screening. Historically, this has included colonoscopies every 10 years or stool tests every 1–3 years, both of which detect early-stage cancers and enable the removal of precancerous polyps, potentially preventing cancer altogether.
Blood tests, Ladabaum emphasised, should currently serve as a supplemental option rather than a replacement for these more established methods. “For now, if you’re willing and able to do a colonoscopy or stool-based test, don’t switch to a blood test,” he advised. Additionally, he stressed the importance of follow-up colonoscopies for individuals who receive positive blood test results.
Despite the current limitations, Ladabaum acknowledged that future advancements in blood test technology could improve their effectiveness. Until then, experts encourage a combination approach to maximise screening rates and effectiveness.
Reference
Ladabaum U et al. Projected impact and cost-effectiveness of novel molecular blood-based or stool-based screening tests for colorectal cancer. Ann Intern Med. 2024; DOI:10.7326/ANNALS-24-00910.
