Screen-film mammography versus full-field digital mammography with soft-copy reading: randomized trial in a population-based screening program--the Oslo II Study

Abstract

Purpose: To prospectively compare cancer detection rates, recall rates, and positive predictive values at screen-film mammography (SFM) with those at full-field digital mammography (FFDM) with soft-copy reading in a population-based screening program in Norway.

Materials and methods: Of 43,429 women invited, 25,263 women aged 45-69 years attended the screening program and were randomized, with adjustments for age and area of residence, to undergo SFM or FFDM. Two standard views of each breast were acquired. Independent double reading was performed with use of a five-point rating scale for probability of cancer. Recall rates, positive predictive values, and cancer detection rates were compared for two age groups (45-49 and 50-69 years) by using the chi(2) test.

Results: Overall, 73 cancers in 17,911 women were detected at SFM (detection rate, 0.41%), compared with 41 cancers in 6,997 women at FFDM (detection rate, 0.59%; P =.06). In the group aged 50-69 years, 56 cancers in 10,304 women were detected at SFM (detection rate, 0.54%), compared with 33 cancers in 3,985 at FFDM (detection rate, 0.83%); the difference in cancer detection rates approached significance (P =.053). In the group aged 45-49 years, 17 cancers in 7,607 women were detected at SFM (detection rate, 0.22%), compared with eight cancers in 3,012 at FFDM (detection rate, 0.27%). Recall rates in both age groups were significantly higher at FFDM than at SFM (P <.05), but positive predictive value was not significantly different.

Conclusion: FFDM allowed a higher cancer detection rate than did SFM in the group aged 50-69, although the difference did not reach statistical significance. The detection rate was nearly equal for the two modalities in the group aged 45-49. SFM and FFDM with soft-copy reading are comparable techniques for population-based screening mammography programs.