Screening with digital mammography: 2-year experiences from Vestfold County, Norway

Purpose

To compare the results from high-volume screening using full-field digital mammography (FFDM) with screen film mammography (SFM) in the Norwegian Breast Cancer Screening Programme (NBCSP).

Materials and methods

The NBCSP offers biennial two-view mammography screening to all Norwegian women aged 50–69. As the only county, Vestfold used FFDM during the prevalence round (2004–2005) (Lorad Selenia; Hologic, USA). Double reading was performed on soft-copy workstations (Sectra MX, Sweden). In total 18,369 women were screened and 142 cases of breast malignancies were diagnosed. The results were compared with the prevalence found in all other Norwegian counties (1996–2004), all using standard SFM.

Results

Recall rates All reasons

FFDM, 4.9%; SFM, 5.4% (P = 0.002).

Positive mammographic findings

FFDM, 4.1%; SFM, 4.2%.

Technical reasons

FFDM, 0.2%; SFM, 0.6% (P < 0.001).

Detection rates All malignancies

FFDM, 0.77%; SFM, 0.65% (P = 0.057).

Invasive tumours

FFDM, 0.55%; SFM, 0.54%.

Ductal carcinoma in situ (DCIS)

FFDM, 0.22%; SFM, 0.11% (P < 0.001).

No statistically significant differences were found concerning tumour size or involvement of axillary lymph nodes.

Conclusion

FFDM had a higher detection rate for DCIS but no difference was observed for invasive tumours. Recall rates were lower due to fewer technically inadequate examinations. FFDM performs well in high-volume population-based screening.