Objective: The purpose of this study was to compare the diagnostic accuracy of digital mammography with that of screen-film mammography in concurrent cohorts participating in the same population-based screening program.
Materials and methods: In a retrospective study covering 2004-2005, we compared digital with screen-film mammography in two concurrent screening cohorts of women 50-69 years old participating in a screening program operated from mobile units. Each cohort had 14,385 participants matched by age and interpreting radiologist from all participants consecutively registered. We compared recall and cancer detection rates.
Results: The recall rate was higher for digital mammography (4.56% vs 3.96%, p = 0.01), particularly when clustered microcalcifications were the only finding (1.05% vs 0.41%, p = 10(-6)) and for younger women (50-59 vs 60-69 years, 5.12% vs 4.17%, p = 0.009). The higher recall rate for digital mammography was mainly evident at incidence screening. The recall rate due to poor technical quality was lower with digital mammography (0.27% vs 0.50%, p = 0.002), possibly because real-time feedback was available. The detection rate was higher for digital mammography (0.72% vs 0.58%, p = 0.14), particularly for cancers depicted as clustered microcalcifications (0.26% vs 0.12%, p = 0.007), in younger (50-59 years) women (0.63% vs 0.42%, p = 0.09), and in denser breasts (1.09% vs 0.53%, p = 0.24). No significant difference was observed in positive predictive value on recall for digital mammography or screen-film mammography. Early cancer (pTis, pT1mic, pT1a) was more frequent in cancer detected with digital mammography than in that detected with screen-film mammography (41.3% vs 27.3%, p = 0.06).
Conclusion: Digital mammography may be more effective than screen-film mammography in contemporary screening practice in mobile units. The data indicate that digital mammography depicts more tumors than does screen-film mammography, especially lesions seen as microcalcifications. The potential association with improved outcome warrants further study.