Computed Tomography Colonography Compared With Colonoscopy for Patients at Increased Risk of Colorectal Cancer

Article Outline

• Copyright

Computed tomographic (CT) colonography may offer patients at increased risk of colorectal cancer (CRC) an alternative to colonoscopy that is less invasive, is better tolerated, and has adequate diagnostic accuracy, according to a study in the June 17, 2009, issue of JAMA.

“Colorectal cancer (CRC) accounts for approximately 210,000 deaths each year in Europe. Being less invasive and thus more tolerable, CT colonography may increase acceptability and adherence to screening, but little information is available on its performance,” the authors write. Daniele Regge, MD, of the Institute for Cancer Research and Treatment, Candiolo, Turin, Italy, and colleagues assessed the accuracy of CT colonography in detecting advanced colorectal neoplasia in asymptomatic individuals at increased risk of CRC using colonoscopy as the reference standard. The multicenter study included individuals at increased risk of CRC owing to either family history of advanced neoplasia in first-degree relatives, personal history of colorectal adenomas, or positive results from fecal occult blood tests (FOBTs). Each participant underwent CT colonography followed by colonoscopy on the same day.

Of 1,103 participants, 937 were included in the final analysis: 373 cases in the family history group, 343 in the group with personal history of adenomas (had a polyp removed), and 221 in the FOBT-positive group. The prevalence of advanced neoplasia was 7.5% in the family history group, 11.1% in the postpolypectomy group, and 50.2% in the FOBT-positive group.

Overall, CT colonography identified 151 of 177 participants with advanced neoplasia ≥6 mm (sensitivity, 85.3%) and accurately classified results as negative for 667 of 760 participants without such lesions (specificity, 87.8%). The positive and negative predictive values were 61.9% and 96.3%, respectively. The negative predictive value ranged between 84.9% in the FOBT-positive group to 98.5% in the family history group.

The authors contend that these results “suggest a potentially effective use of CT colonography as an alternative to colonoscopy for screening individuals with family history of advanced colorectal neoplasia. Computed tomographic colonography has been shown to be better accepted than colonoscopy and has a negligible risk of serious adverse events; thus, it may help increase the low adherence reported for individuals who are candidates for screening, which is the main negative factor affecting its efficacy in reducing mortality from CRC.”

In an accompanying editorial, Emily Finlayson, MD, MS, of the University of Michigan, Ann Arbor, notes that although the use of CT colonography as a screening and surveillance modality is still a matter of debate, the new study suggests that CT colonography “may be an acceptable alternative to colonoscopy in patients with a history of adenoma and those with a family history of colorectal neoplasm. The question remains whether clinicians are willing to accept a study with decreased sensitivity for the potential of increased adherence with recommended screening and surveillance guidelines.”

See “Diagnostic accuracy of computed tomographic colonography for the detection of advanced neoplasia in individuals at increased risk of colorectal cancer,” JAMA 2009;301:2453–2461 and 2498–2499.