ABSTRACT
In many countries, regular breast cancer screening with mammography is oered to women over 40 or 50 years of age to detect early signs of breast cancer. Eectiveness of mammographic screening has been established by randomized controlled trials and by observation of a signicant reduction in breast cancer mortality in the screened population in countries where large screening programs were established in the 1990s. In screening mammograms, clustered microcalcications and breast masses are the most important signs of cancer in mammograms. While microcalcications are most often associated with noninvasive in situ cancers, masses reect the presence of invasive
malignant processes. e majority of cancers in screening are detected by masses, and most palpable lesions in symptomatic women appear as masses.
