Background
Although various radiographic modalities are readily available to identify lesions that are suspicious for breast cancer, mammography remains the mainstay of breast cancer screening. Role of breast sonogram is confined mainly to the diagnostic follow-up of a mammographic abnormality because it may help clarify features of a potential lesion. The role of magnetic resonance imaging (MRI) for breast cancer screening is still evolving; currently MRI screening, in combination with mammography, is reserved to the screening of high-risk patients only.
In 2015, an estimated 231,840 new cases of invasive breast cancer were diagnosed, along with an estimated 60,290 additional cases of in situ breast cancer. Only lung cancer accounts for more cancer deaths among women.
Overall breast cancer death rates decreased 36% from 1989 to 2012, because of both improvement in treatments and earlier detection.
The lifetime risk of being diagnosed with breast cancer is 12.3%, or 1 in 8.
Due to the magnitude of the disease, its psychosocial impact, and associated morbidity and mortality, screening for early diagnosis forms a pivotal part of the struggle against this cancer.
According to the National Health Interview Survey, 69% of women 45 years and older have had a mammogram within the past 2 years. Since 1987, the prevalence of women 40 years and older who have had a mammogram has increased from 29% to 70%.
According to the U.S. Preventive Services Task Force, the number of breast cancer deaths averted by screening and early treatment increases with age: over a 10-year period, screening 10,000 women aged 60-69 years will result in 21 fewer deaths from breast cancer; 8 fewer deaths in 10,000 women 50-59 years; and 3 fewer deaths in 10,000 women 40-49 years.