Clinical pathology selected abstracts

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Editor: Deborah Sesok-Pizzini, MD, MBA, chief medical officer, Labcorp Diagnostics, Burlington, NC, and adjunct professor, Department of Clinical Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia.

Cost-effectiveness of liquid biopsy for colorectal cancer screening

March 2024—Despite research into colorectal cancer screening and clinical experience, screening uptake remains low. Colorectal cancer (CRC) screening involves noninvasive tests, such as a fecal immunochemical test (FIT) and stool-based DNA tests, as well as invasive tests, such as colonoscopy. The latter has the best performance characteristics for early cancer and adenoma detection. The average adherence to CRC screening is 60.6 percent for U.S. patients aged 50 to 75 years, which is well below the 80 percent goal for adherence set by the National Colorectal Cancer Roundtable and American Cancer Society. Offering stool-based tests to patients who refuse colonoscopy results in only a modest increase in adherence, to 67 percent. Of interest, CRC that develops in unscreened patients is estimated to account for 28 to 44 percent of CRC deaths. No blood test is yet recommended for CRC screening. Blood tests and liquid biopsies using circulating tumor DNA-based markers are being developed for single-cancer and multicancer early detection (MCED), including for CRC. Although investment in liquid biopsy for its potential to detect early cancer has been increasing, it is unclear whether it will be a cost-effective CRC strategy in the United States. The authors conducted a study to estimate the cost-effectiveness of liquid biopsy as a first- or second-line CRC screening strategy in the United States compared to no screening and screening with three approved methods, including colonoscopy, FIT, and stool DNA. They hypothesized that liquid biopsy would improve CRC detection and decrease the number of deaths from the disease. The authors performed an economic evaluation using a Markov model to compare no screening to colonoscopy, liquid biopsy, liquid biopsy following nonadherence to colonoscopy, stool DNA, and FIT. Adherence to first-line screening with colonoscopy, stool DNA, or FIT was assumed to be 60.6 percent, and adherence to liquid biopsy was assumed to be 100 percent. Patients who did not adhere to colonoscopy, stool DNA, or FIT were not offered other CRC screening methods. Among the colonoscopy-liquid biopsy hybrid study participants, liquid biopsy was the second-line screening for those who deferred colonoscopy. Additional scenario analyses were performed to include the possibility of liquid biopsy detecting polyps. The model outcomes included life expectancy, total cost, and incremental cost-effectiveness ratios. A strategy was considered cost-effective if it had an incremental cost-effectiveness ratio of less than the U.S. willingness-to-pay threshold of $100,000 per life-year gained. The results showed that in a simulated cohort of patients aged 45 years who had an average risk of developing CRC, colonoscopy was the most cost-effective strategy, with an incremental cost-effectiveness ratio of $28,071 per life-year gained. The colonoscopy-liquid biopsy hybrid had the greatest gain in life-years but had an incremental cost-effectiveness ratio of $377,538. The colonoscopy-liquid biopsy hybrid model had an even greater gain in life-years if liquid biopsy could detect polyps but overall remained too costly. The authors concluded that colonoscopy is a cost-effective strategy for colorectal cancer screening in the general population. With many liquid biopsy tests coming to market, this analysis sets threshold targets for liquid biopsy performance and cost to guide future medical policy decision-making.

Aziz Z, Wagner S, Agyekum A, et al. Cost-effectiveness of liquid biopsy for colorectal cancer screening in patients who are unscreened. JAMA Network Open. 2023;6(11). doi:10.1001/jamanetworkopen.2023.43392

Correspondence: Dr. Chin Hur at ch447@cumc.columbia.edu