CR mammo may underperform

Digital mammography and film-screen mammography deliver comparable breast cancer detection performance, but computed radiography (CR) mammography was less likely by 21 percent to help detect breast cancer, according to a study published online May 14 in Radiology.

Although multiple studies have evaluated digital mammography, few have focused on CR mammography, and none of these has focused on concurrent cohorts.

Anna M. Chiarelli, PhD, of the department of prevention and cancer control at Cancer Care Ontario in Toronto, and colleagues attempted to fill this gap and compare digital and CR mammography with film-based mammography in large concurrent cohorts.

The researchers identified three groups of women ages 50-74 years who underwent screening mammography between Jan. 1, 2008, and Dec. 31, 2009. The sample included 403,688 women who underwent screen-film exams, 220,520 who underwent digital mammography and 74,190 who underwent CR mammography.

A total of 61 percent of cancers were detected by screen-film mammography, 32.4 percent with digital and 6.6 percent with CR, yielding similar detection rates for film and digital exams. However, CR mammography was less likely—by 21 percent—to help detect breast cancers, according to the researchers.

Digital mammography was more likely—by 30 percent—to help detect in situ cancers than screen-film exams.

Recall rates were higher for digital mammography than for film exams, and the adjusted odds reached borderline significance. The recall rates for CR were lower than for film, but adjusted odds did not demonstrate significance.

“Overall, this study found that digital mammography with [digital] technology is at least equivalent to [screen-film mammography] in breast screening for women 50-74 years of age,” wrote Chiarelli et al.

The researchers’ results for CR mammography differed from earlier studies and showed lower recall rates and positive predictive values. “Compared with [screen-film mammography use of CR] could result in about 10 fewer cancers detected per 10,000 women screened.”

Chiarelli and colleagues recommended programs that offer digital and CR mammography monitor performance of both types of systems and consider counseling women on the potentially lower cancer detection rates with CR.