How CT colonography compares to other popular colorectal cancer screening options
Less than one year after the Center for Medicare and Medicaid Services recommended the inclusion of computed tomography colonography (CTC) as a screening tool for colorectal cancer, a new paper is detailing the exam’s utility in early cancer detection.
At the start of 2025, CMS issued a national coverage determination on CTC that led to widespread insurance coverage of the exam. It is recommended that patients undergo a CTC—one of the least invasive screening tools available—every five years.
Fecal immunochemical tests, which patients can often complete themselves without ever setting foot inside a doctor’s office, also are popular among individuals seeking less invasive screening options. Such tests are recommended at 2-year intervals.
Given the less intrusive nature of these exams in comparison to colonoscopies, which are considered the gold standard for CRC detection, the tools are growing in popularity among patients. As such, experts sought to get a better idea of how they compare to one another, sharing their findings Tuesday in Radiology.
“As the removal of precancerous lesions represented by adenomatous polyps halts their progression to CRC, screening serves as a preventive health intervention that can decrease the incidence of [colorectal cancer],” Lapo Sali, MD, PhD, with the Institute for Cancer Research, Prevention and Clinical Network, Florence, Italy, and colleagues noted. “A 5-year interval is recommended for screening with CTC, but only one study, to our knowledge, has reported the results of a second screening CTC examination in average-risk individuals. In contrast, 2 years is the established interval for [fecal immunochemical tests], which is the most common screening tool in Europe.”
For their work, the team conducted a secondary analysis of data from the SAVE trial, which compared the effectiveness of a single CTC exam versus three biennial fecal tests for cancer screening in average-risk adults. After the trial’s completion, all participants under 70 were invited to continue to undergo biennial fecal screening. Incidence rates of colorectal cancer and advanced adenoma from those screenings and the CTC exams included in the trial were compared to determine diagnostic yield and appropriate screening interval timing.
Overall, CTC screening at the 5-year interval yielded 9 cancer diagnoses, 1 of which was considered interval, while the fecal tests cohort included 58 diagnoses. The team did not observe a statistically significant difference in cancer incidence rates between the two groups.
All stage 4 diagnoses occurred in the fecal testing group; follow-up evaluations revealed persistently and significantly higher incidence rate of advanced adenoma in the CTC group, highlighting the exam's early detection potential. The researchers suggested these findings indicate that the CTC screening interval recommendations remain appropriate. What’s more, they added that CTC screening may be a more effective option for earlier diagnoses.
“In our study, the overall lack of a significant difference in the incidence of CRC (adjusted hazard ratio, 0.73 [95% CI: 0.36, 1.47]) and the significantly greater incidence of [advanced adenoma] (adjusted hazard ratio, 1.46 [95% CI: 1.11, 1.92]), along with the lack of stage 4 [colorectal cancers] in the CTC arm, suggest that screening CTC might be associated with earlier diagnosis than biennial screening [fecal immunochemical tests],” the authors noted. “Additionally, considering the previously observed significantly lower number of false-positive results from screening CTC than screening biennial [fecal immunochemical tests], the overall performance of CTC as a screening test appears to exceed that of biennial [fecal immunochemical tests].”
The study abstract is available here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.