Virtual Colonoscopy Bests Barium Enema for CRC Diagnosis

Computed tomographic colonography (CTC), or virtual colonoscopy, was more sensitive than barium enema in detecting colorectal cancer and large polyps, according to the large multicenter randomized SIGGAR trial, the results of which were published recently in The Lancet.

“We found that CTC detected significantly more cancers or large polyps than did BE, and missed fewer cancers,” investigator Steve Halligan, MD, professor of gastrointestinal radiology at the University College London, said in an interview. “Barium enema should be abandoned for investigation of patients with symptoms suggestive of colorectal cancer and replaced by CTC as soon as local circumstances and expertise allow.”

The trial, which was conducted at 21 hospitals in the United Kingdom and analyzed 3,804 patients, was designed to determine if barium enema could accurately diagnosis colorectal cancer and identify large polyps in symptomatic patients compared with CTC.

“Although still widely used, there were concerns that barium enema was not sensitive enough,” Halligan said.

Patients in the study were randomly assigned to undergo either CTC (n=1,277) or barium enema (n=2,527). The median age of patients was 69 years and 61 percent were women.

Diagnosis with CTC yielded a significantly greater detection rate of colorectal cancer or large polyps compared with patients in the barium enema group (7.3 percent vs. 5.6 percent; RR=1.31; 95 percent CI, 1.01-1.68).

Patients were followed for three years. During that time, three patients who had undergone CTC were subsequently diagnosed with colorectal cancer. CTC missed a colorectal cancer diagnosis in 7 percent of patients, or three of 45. Twelve patients who underwent barium enema were subsequently diagnosed with colorectal cancer, for a missed diagnosis rate of 14 percent, or 12 of 85 patients. Although this difference is not statistically significant, the researchers pointed out that it “is similar to rates reported in several clinical trials.”

Patients who underwent CTC had higher rates for additional colonic investigation (23.5 percent vs. 18.3 percent; P=.0003), mostly due to an increased need for investigation of polyps 10 mm or larger.

In addition, the researchers reported that patients who underwent barium enema reported a lower satisfaction with the procedure and experienced greater physical discomfort compared with CTC.

“[Barium enema] is also more physically demanding because several patient positions are needed, whereas only two (usually prone and supine) are needed for CTC,” the researchers wrote. “This feature of CTC makes it more suitable than [barium enema] for frail elderly patients, who account for many of those with symptoms.”