If you are a woman between 45 and 49 years old, should you attend an organised mammography screening programme?
Research results
Below you will find the results of a group of women who were screened compared to those who were
not screened.
The balance between clinical benefits and harms is one major consideration for a guideline panel to
make a recommendation for screening. To decide whether to do mammography screening or not, we
selected outcomes critical to making the decision: breast cancer stage IIA, breast cancer stage III, rate of
mastectomies, breast cancer mortality, overdiagnosis, and false-positive related adverse effects.
Events per 100 000 women
Outcomes
Mammography screening
Happens to 100000 people
No mammography screening
Happens to 100000 people
Certainty of the evidence
Breast cancer stage IIA
46 fewer
334
per 100000
380
per 100000
very low
certainty
certainty
Breast cancer stage III+ or tumour size ≥40 mm
88
per 100000
90
per 100000
low
certainty
certainty
Rate of mastectomies
1080
per 100000
180 fewer
900
per 100000
low
certainty
certainty
Breast cancer mortality
623
per 100000
700
per 100000
moderate
certainty
certainty
Overdiagnosis
Overdiagnosis is estimated to be 12.4% (95% CI 9.9%-14.9%) from a population perspective.
moderate
certainty
certainty
False-positive related adverse effects: psychological
False-positive mammograms are associated with greater anxiety and distress about breast cancer as well as negative psychological consequences that may last up to three years. Women who had further testing following their routine mammogram experienced significant short-term anxiety.
low
certainty
certainty
False-positive related adverse effects: Biopsies and surgeries
2.2% and 1.1% (from 1.7 million initial screens and 5.9 million subsequent screens) of all screening examinations resulted in needle biopsy among women without breast cancer. 0.19% and 0.07% (from 1.7 million initial screens and 5.9 million subsequent screens) of all screening examinations resulted in surgical interventions among women without breast cancer*.
very low
certainty
certainty
*Cross-sectional data from the EUNICE Project (women aged 50 to 69): 17 countries, 20 screening programmes, 1.7 million initial screens, 5.9 million subsequent screens
Comparison
Mammography screening
Benefits
If you were to have a mammography, your risk of stage II or greater breast cancer is probably reduced, and your risk of death from breast cancer may be reduced. The risk of dying from breast cancer is reduced by between 4 (low risk population) and 8 (high risk population) per ten thousand women offered screening. This corresponds to a reduction of 5 to 10 breast cancer deaths per ten thousand in women actually screened*.
For women between 45 and 49 years old, the Guidelines Development Group members agreed they would have a larger anticipated reduction in breast cancer mortality, and greater health benefits compared to women between the ages of 40 and 44, partly due to higher absolute incidence and mortality from breast cancer in women aged 45-49 than in women aged 40-44. There may be little or no change to your risk of death from other causes, or of developing breast cancer of stage III or higher.
Harms
There is a risk of being overdiagnosed. An overdiagnosed cancer is a cancer diagnosed by screening which is so slow-growing that it would never have been diagnosed in a person's lifetime if the person had not been screened. It is hard to tell which cancers are of this type, and which are not, so treatment is the same as if it was not overdiagnosed. Therefore, you will be advised to have treatment, possibly including mastectomy (removal of the breast). There is also a small chance of a false positive mammography result, which means that you would have further tests after screening. These tests will confirm that you do not have cancer, but you may have suffered unnecessary anxiety and distress.