An investigation into why two-view mammography is better than one-view in breast cancer screening

AIM: To determine why two-view mammography in screening for breast cancer i s more effective than using a single medio-lateral oblique view, MATERIALS AND METHODS: In the United Kingdom Coordinating Committee on Canc er Research randomized trial of one- vs two-view mammography in breast cant er screening the oblique view was assessed by one radiologist and two views (oblique and cranio-caudal) assessed by another. For the present study the mammographic films were retrieved from the screening centres and assessed by three consultant radiologists. Mammographic films were available from 11 0 women; 87 had their breast cancer detected by both one and two views and in 23 it was missed by one view but detected using two views, Outcome measu res were breast size, location and size of the cancer, mammographic feature s, presence of microcalcification and overall radiological assessment. RESULTS: Although 23 cancers were missed in the original trial when one vie w was used, only two were not visible on the oblique view. Cancers missed u sing a single oblique view (and only detected if the cranio-caudal view was available with the oblique) tended to he smaller by about 4 mm (P = 0.05), centrally located in the breast (P = 0.16), not spiculated or round, (P le ss than or equal to 0.001) and lacked microcalcification (P = 0.15), Breast size and breast radiographic density were not significantly associated wit h breast cancer detection. CONCLUSIONS: The results provide the basis for the observation that two-vie w mammographic screening is more effective than one-view mammographic scree ning, (C) 2000 The Royal College of Radiologists.