Key messages from scientific research that's ready to be acted on
Got It, Hide thisCanelo-Aybar C, Ferreira DS, Ballesteros M, et al. Benefits and harms of breast cancer mammography screening for women at average risk of breast cancer: A systematic review for the European Commission Initiative on Breast Cancer. J Med Screen. 2021 Feb 25:969141321993866.
In women who have average risk for cancer, what are the benefits and harms of screening for breast cancer in women less than 50 years, between 50 to 69 years, or between 70 to 74 years of age?
Breast cancer screening involves regular examination of women’s breasts with mammography to detect cancer. Screening is more likely to detect cancer in early stages, when it is small and has had less chance to spread. When detected early, there are more treatment options and often a better outcome. Breast cancer screening may also lead to overdiagnosis, where a cancer that would not have caused harm during a woman’s lifetime is detected and treated, or to false-positive results, where the screening test is positive, but follow-up tests are negative for cancer. False-positive results can cause anxiety and psychological distress due to worry about having breast cancer when breast cancer is not actually present.
The researchers did a systematic review based on studies available up to June 2018.
They found 4 systematic reviews of observational studies and reports from 9 randomized controlled trials.
Key features of the trials were:
Compared with women who did not receive an invitation to screening, screening
In women with average risk for breast cancer, screening mammography reduces breast cancer–related deaths in those aged 50 to 69 years. In women less than 50 years or more than 70 years of age, the balance of benefits and harms are less clear. Women should discuss the option of screening with their health care provider to determine what is best for them. It is important to note that these recommendations do not apply to women who have a higher-than-average risk for breast cancer.
Outcomes | Age groups | Number of studies (number of women) | Effect of screening for breast cancer compared with no screening* | Quality of evidence† |
Death due to breast cancer | < 50 years | 8 studies (348,478 women) | No difference in effect | Moderate |
| 50 to 69 years | 6 studies (249,930 women) | An average of 138 to 483 fewer women out of 100,000 would die due to breast cancer (ranging from 60 fewer deaths to 714 fewer deaths)‡ | High |
| 70 to 74 years | 2 studies (18,233 women) | No difference in effect | High |
Overdiagnosis§ | < 50 years | 1 trial (50,430 women) | For every death due to breast cancer that is avoided, about 4 more women will be diagnosed with cancer that would not have caused harm during their lifetime | Moderate |
| 50 to 69 years | 2 trials (64,117 women) | For every death due to breast cancer that is avoided, about 4 more women will be diagnosed with cancer that would not have caused harm during their lifetime | Moderate |