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Breast cancer is the second leading cause of cancer death among women in the United States.
What Is Breast Cancer Screening?
Screening for breast cancer means looking for signs of breast cancer in all women of a certain age or with certain risk factors, even if they have no symptoms. The goal of screening is to catch cancers early. Screening for breast cancer lowers the risk of dying of it; early-stage cancers are easier to treat than later-stage cancers, and the chance of survival is higher. Screening for breast cancer is done mostly by mammography (breast x-ray).
Benefits and Harms of Mammograms
In general, having routine mammograms lowers the risk of dying of breast cancer. But mammograms are not perfect tests. They can miss some cancers, and they can find lesions that may look like cancers but are not actually cancers (false-positive results), resulting in additional testing and procedures. They can also find very low-risk cancers that would never have caused any health problems if they were never found or treated (overdiagnosis). A JAMA Patient Page published on December 17, 2014, discusses the pros and cons of screening for breast cancer in greater detail.
When Should You Start Being Screened?
Because all women are different, there is not one universal “best” age to start screening for breast cancer. Mammograms are not very useful in younger women because the breast tissue is more dense, making it harder to see potential cancers. Also, the earlier women start having mammograms, the higher the lifetime chance of having a false-positive result or a case of overdiagnosis. On the other hand, delaying screening for too long can lessen the mortality benefit of catching cancers early. Some women with a high risk of breast cancer (particularly those with family members who have had breast cancer) should start screening earlier than others. For younger women, screening may include tests other than mammograms.
In the United States, there are different sets of recommendations from different organizations. These recommendations were formed by carefully reviewing a large amount of data from a large number of studies about the benefits and harms of breast cancer screening.
The US Preventive Services Task Force (USPSTF) developed a guideline in 2009 and currently recommends that women aged 50 to 74 years get a screening mammogram every 2 years. For women younger than 50 years, some may choose to be screened based on individual risk factors.
In the October 20, 2015, issue of JAMA, the American Cancer Society (ACS) updated its breast cancer screening guidelines. The ACS currently recommends that women start screening at age 45 years. Yearly screening is recommended until age 54 years; after that age, some women can undergo screening every 2 years. Screening should continue as long as there is a life expectancy of 10 years or more. For women younger than 45 years, some may choose to be screened based on individual risk factors.
The USPSTF recommends fewer screening mammograms because too many may lead to overdiagnosis and overtreatment. The ACS recommends more frequent screening based on the belief that more screenings are necessary to catch more tumors at an earlier stage. The differences between the 2 groups’ recommendations represent different ideas about balancing the benefits and the potential harms of screening.
Every woman needs to make her own decision about balancing risks versus benefits. Talk to your primary care doctor about which breast cancer screening approach is best for you.
Centers for Disease Control and Preventionwww.cdc.gov/cancer/breast/
Sources: Oeffinger KC, Fontham ETH, Etzioni RB, et al. Breast cancer screening for women at average risk: 2015 guideline update from the American Cancer Society. JAMA. doi: 10.1001/jama.2015.12783.
Pace LE, Keating NL. A systematic assessment of benefits and risks to guide breast cancer screening decisions. JAMA. 2014;311(13):1327-1335.
Topic: Preventive Medicine
Jin J. Breast Cancer Screening Guidelines in the United States. JAMA. 2015;314(15):1658. doi:10.1001/jama.2015.11766
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