Breast Cancer Screening

Breast cancer screening refers to the medical screening of asymptomatic, apparently healthy women for breast cancer in an attempt to achieve an earlier diagnosis. The assumption is that early detection will improve outcomes. A number of screening test have been employed including: clinical and self breast exams, mammography, genetic screening, ultrasound, and magnetic resonance imaging.

A clinical or self breast exam involves feeling the breast for lumps or other abnormalities. Evidence however does not support its use in women with a typical risk for breast cancer. The use of mammography in universal screening for breast cancer is controversial. Clinical trials have found a relative reduction in breast cancer mortality of 10% (2.4 deaths per 100,000 person-years) attributable to screening but this difference was non significant. The Cochrane Collaboration review found a 15% reduction in mortality, but the absolute reduction in breast cancer mortality was 0.05%, and due to harm from false positive screening and increased mortality from treatment complications, they could not conclude whether screening did more harm than good. The Nordic Cochrane Collection (2012) reviews updated research to state that advances in diagnosis and treatment make mammography screening less effective today. They state screening is “no longer effective.” They conclude that “it therefore no longer seems reasonable to attend” for breast cancer screening at any age, and warn of misleading information on the internet.

Many national organizations recommend it for most older women. If screening mammography (as opposed to diagnostic mammography) is chosen for women at normal risk for breast cancer, it should only be done every two years in women between the ages of 50 and 74. Several tools are available to help target breast cancer screening to older women with longer life expectancies. Similar imaging studies can be performed with magnetic resonance imaging.

Earlier, more aggressive, and more frequent screening is recommended for women at particularly high risk of developing breast cancer, such as those with a confirmed BRCA mutation, those who have previously had breast cancer, and those with a strong family history of breast and ovarian cancer.

Abnormal findings on screening are further investigated by surgically removing a piece of the suspicious lumps (biopsy) to examine them under the microscope. Ultrasound may be used to guide the biopsy needle during the procedure. Magnetic resonance imaging is used to guide treatment, but is not an established screening method for healthy women.