- Author: Muhammad Neaman Siddique, MBBS; Chief Editor: Eugene C Lin, MD more...
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.
Breast cancer is the most frequently diagnosed female cancer in the world and is the leading cause of cancer-related mortality in women. In the United States, it is the second most common cause of cancer death in women across all age groups and is the main cause of death in women aged 40-59.
The lifetime probability of developing breast cancer is 1 in 6 overall (1 in 8 for invasive disease). 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. Breast cancer mortality has shown a decline since 1975, which may be attributable to both early diagnosis by virtue of screening mammograms and improvements in adjuvant therapies.
In studies, mammography has clearly been shown to increase the detection of breast cancer at an earlier stage. Based upon consistent data from multiple randomized trials, a strong consensus has been developed in favor of routine screening mammography for all women aged 50-69. Consensus, however, is not as strong in favor of routine screening among women aged 40-49 or women over the age of 70, and in terms of how frequently these patient populations should be screened.
Based upon pooled data form 8 trials, the United States Preventive Services Task Force (USPSTF) has given an estimate that 1904 women aged 39-49 (credible interval, CrI 929 to 6378 women) would need to be screened to prevent one death from breast cancer after at least 11 years of observation, compared to 1339 women in their 50s (CrI 322-7455) and 377 women in their 60s (CrI 230-1050). Moreover, false-positive readings are more common in younger women, both because the tests are less specific and because breast cancer occurs less commonly in that population.[7, 8]
The American Medical Association, the American Cancer Society, the American College of Radiology, the American College of Obstetrics and Gynecology, the National Cancer Institute, and the National Comprehensive Cancer Network (NCCN) recommend starting routine screening at the age of 40. The American Academy of Family Physicians recommends screening mammography every 1-2 years for women aged 40 and older.
On the other hand, the USPSTF, the American College of Physicians, and the Canadian Task Force on the Periodic Health Examination recommend beginning routine screening at age 50. Most of the groups do not clearly state the age when breast cancer screening should stop. The USPSTF recommends mammography screening until age 74. The American College of Radiology recommends continuing screening until life expectancy becomes 5-7 years, on the basis of age and/or comorbidities.
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