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 is more effective than using a single medio-lateral oblique view, MATERIALS AND METHODS: In the United Kingdom Coordinating Committee on Cancer Research randomized trial of one- vs two-view mammography in breast canter 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 110 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 measures were breast size, location and size of the cancer, mammographic features, presence of microcalcification and overall radiological assessment. RESULTS: Although 23 cancers were missed in the original trial when one view was used, only two were not visible on the oblique view. Cancers missed using 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 less than or equal to 0.001) and lacked microcalcification (P = 0.15), Breast size and breast radiographic density were not significantly associated with breast cancer detection. CONCLUSIONS: The results provide the basis for the observation that two-view mammographic screening is more effective than one-view mammographic screening, (C) 2000 The Royal College of Radiologists.