Most major health organizations have concluded that mammography saves lives. However, there is ongoing debate over:
Mammography in women 40 to 49 saves lives, but the benefit is less than for older women.
Some health organizations have concluded that the modest survival benefits of mammography in women in their 40s outweigh the risks of false positive results. The National Comprehensive Cancer Network recommends routine mammography for women starting at age 40 and the American Cancer Society recommends starting at age 45 [15,105].
The U.S. Preventive Services Task Force meta-analysis of eight randomized controlled trials found that mammography modestly reduced the risk of breast cancer mortality (death) in women 40 to 49 . This study found that to prevent one breast cancer death, 1,904 women 40 to 49 would need to be screened with mammography .
Weighing the benefits and risks, the Task Force does not recommend routine mammography for all women in their 40s .
Instead, the Task Force, as well as the American College of Physicians, recommends that women 40 to 49 discuss the benefits and risks of mammography screening with their health care providers. Then together, they should make informed decisions about when to start mammography screening [13,18,105]. The American Cancer Society recommends informed decision-making for women ages 40 to 44 .
Informed decisions are guided by a woman's breast cancer risk profile. Women at higher risk of breast cancer are more likely to benefit from mammography [18,105]. Decisions should also be guided by a woman’s preferences based on the potential pros and cons of mammography .
The U.S. Preventive Services Task Force recommends that routine mammography screening begin at age 50 .
There are valid concerns about the over-diagnosis and over-treatment of ductal carcinoma in situ (DCIS) and small, slow-growing invasive breast cancers with mammography screening.
Since the introduction of mammography in the 1980s, the number of women diagnosed with DCIS has increased a lot. In 2015, it is estimated that there will be about 50,000 new cases of DCIS .
Over-diagnosis occurs when a mammogram finds DCIS or small, invasive breast cancers that would have never caused symptoms or problems if left untreated. These breast cancers may never grow and some may even shrink on their own. Or, a person may die from another cause before the breast cancer became a problem.
Some researchers estimate that about 20 to 30 percent of DCIS and invasive breast cancers found with mammography may be over-diagnosed .
Although DCIS is non-invasive, without treatment, the abnormal cells can sometimes become invasive over time. Left untreated, about 40 to 50 percent of DCIS cases may progress to invasive breast cancer . (These numbers are estimates.) Higher grade DCIS may be more likely than lower grade DCIS to turn into invasive cancer if left untreated.
At this time, there is no way to tell which cases of DCIS will become invasive breast cancer and which will not. So, women with DCIS are treated with lumpectomy (also called breast conserving surgery) plus radiation therapy or mastectomy. Some women are also treated with hormone therapy.
Since not all cases of DCIS will become invasive breast cancer, some women with DCIS may be over-treated. These women never would have developed invasive breast cancer, with or without treatment.
Researchers are studying ways to identify the cases of DCIS most likely to turn into invasive breast cancer. This would allow treatment to be targeted to those who are at higher risk and might allow some people to avoid treatment.
At this time, however, the standard of care is to treat every case of DCIS as if it might turn into invasive breast cancer.
Learn more about DCIS.
Read more from our Chief Scientific Advisor, Dr. Eric Winer, as he comments on the issue of mammography leading to over-diagnosis and over-treatment.
Despite some ongoing debate, mammography is still the most effective screening tool used today for the early detection of breast cancer.
While any health decision is a personal one that involves weighing benefits and risks, most health organizations recommend women get mammograms on a regular basis.
Learn more about breast cancer screening recommendations for women at average risk.
Learn more about breast cancer screening recommendations for women at higher risk.
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