Double barium enema screening of colorectal cancer gets thumbs-down

Barium enema fluoroscopy has been the bane of radiological practice and subject of radiologists' jokes for more than 80 years. Now a meta-analysis, presented Friday at the ECR meeting, criticizes the quality of published medical studies of the technique. Those studies have led to the conclusion that double barium enema exams cannot be recommended as an alternative to colonoscopy for diagnosing colorectal carcinoma.

Dr. Tamar Sella of Hadassah Medical Center in Jerusalem found that only 12 of 28 studies published since 1980 fulfilled the researchers' inclusion criteria, and none of the studies examined enough patients to produce statistically valid results. The largest study, performed in 1995, included 1831 patients but found only 211 polyps.

"So there was no single study that had large enough numbers to come up with an accurate assessment," Sella said.

Results from the 12 studies were pooled and a meta-analysis was performed to produce viable data. Eight of the 12 involved a high-risk population. Seven compared the double barium enema results with conventional colonoscopy, and five compared the results with flexible sigmoidoscopy.

Double-contrast barium enema exams identified 105 of 134 patients in the seven studies that provided cancer data. Overall, 990 polyps were identified, but only 50% were diagnosed with the barium enema technique. The sensitivity of barium enema rose when only polyps of 1 cm were considered. Of 237 polyps in this category, 155 were identified with double-contrast barium enema.

The overall pooled sensitivity of the technique was 79%, and for 10-mm or larger polyps, the sensitivity was 65%. Even with pooled data, the researchers could not measure the test's sensitivity for polyps small than 10 mm because only four of the 10 studies included such data.

A meta-analysis of conventional CT, published in the American Journal of Roentgenology in 2003, found the pooled sensitivity of CT colonoscopy in the evaluation of 1400 polyps was 81%.

Sella concluded that barium enema CT may be less expensive to perform than CT colonography as a screening test for colorectal cancer, but the approach has not been studied closely enough to know how well it performs.