Computed Tomography Colonography in Fecal Immunochemical Test Positives in a Colorectal Cancer Screening Program

In the Dutch colorectal cancer (CRC) screening program, fecal immunochemical test (FIT)-positives are offered computed tomography colonography (CTC) instead of colonoscopy in case of comorbidities or patient refusal. Literature on CTC in FIT-positives is scarce, and the risk of post-CT interval CRC (PCT-CRC) in this population is unknown.

In this cohort study, we assessed CTC yield, clinical management, and risk of PCT-CRC in FIT-positives who underwent CTC between 2014 and 2019 in the Dutch CRC screening program. Data were linked with the National Cancer Registry to identify PCT-CRCs.

Of 4506 FIT-positives scheduled for CTC (1.32% of all FIT-positives), 2794 (62%) underwent CTC (median age, 69 years; 58.8% male, 72.2% due to comorbidities). CRC was detected in 160 (5.7%), polyps ≥10 mm in 554 (19.8%), and polyps 6 to 9 mm in 512 (18.3%). A total of 1047 additional endoscopies (37.5%) were indicated for polyps ≥6 mm or CRC. A total of 987 additional endoscopies (35.3%) were performed. Histologically confirmed advanced neoplasia (AN) was present in 590 (21.1%), CRC in 112 (4.0%), and advanced adenomas in 502 (18.0%). Sixteen PCT-CRCs (0.6%) occurred during a median follow-up of 49 months (interquartile range, 36-64 months). Quality reporting was often lacking, and 5 complications (0.2%) occurred.

CTC in FIT-positive screenees was associated with a lower AN detection rate and a higher PCT-CRC rate compared with what is known from colonoscopy. A substantial proportion of complications occurred, and quality reporting was often lacking. This underlines the need for a structured quality assurance program for CTCs performed in FIT-positives. Critical appraisal of who to refer for CTC and communication about the benefits and pitfalls of CTC are warranted.