Computed tomography (CT) colonography has been shown to be both cheaper and clinically more effective than multitarget stool DNA (mt-sDNA) testing for population-level colorectal cancer screening, according to peer-reviewed research published in the journal of the Radiological Society of North America.
Colorectal cancer is the world’s second leading cause of cancer-related mortality. Routine examination of the colon and rectum enables early removal of precancerous polyps, thereby reducing the need for late-stage therapies and their associated higher costs and greater risk to patients. In response to rising incidence among younger adults, the United States Preventive Services Task Force, and several professional bodies, have now recommended that screening programmes commence at 45 years of age.
“Conventional optical colonoscopy remains the dominant screening test in the United States, yet it is the most expensive and invasive option,” said lead author Dr Perry J. Pickhardt, John R. Cameron Professor of Radiology and Medical Physics at the University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
Dr. Perry emphasised that recent Medicare coverage expansions have improved access to less invasive modalities, including mt-sDNA testing – which analyses stool for cancer-specific biomarkers – and CT colonography, which employs imaging technology to render non-invasive visualisation of the colon polyps and tumours.
Using a Markov model, the investigators simulated colorectal disease progression in 10,000 individuals aged 45 at baseline, assuming perfect adherence to recommended screening and follow-up until 75 years. Without screening, 7.5 per cent of the cohort developed colorectal cancer.
Both strategies substantially lowered disease incidence versus no screening, but CT colonography achieved a 70–75 per cent reduction, compared with 59 per cent for mt-sDNA. Cost-effectiveness was measured in quality-adjusted life-years (QALYs). Mt-sDNA yielded an incremental cost of nearly US$9,000 per QALY gained, well below the accepted US$100,000 threshold; CT colonography, by contrast, was cost-saving relative to no screening.
Because advanced polyps ≥10 mm pose the greatest malignant risk, the authors evaluated a hybrid CT-based pathway: three-year CT colonography surveillance for small polyps (6–9 mm) and colonoscopic referral only for lesions ≥10 mm. This approach offered the best balance of cost and clinical benefit. Referring all polyps ≥6 mm for colonoscopy was not cost-effective, owing to higher procedural expenses and minimal QALY gains.
“Among safe, minimally invasive options, CT colonography prevents and detects colorectal cancer more effectively – and at lower overall cost – than stool DNA testing,” Dr Pickhardt said.
“Furthermore, CT colonography can simultaneously screen for extracolonic conditions such as osteoporosis and cardiovascular disease.”
The findings bolster the case for wider adoption of CT colonography within national screening programmes, particularly where resource allocation and patient comfort are paramount.