Women aged 40-74 without personal or family history of breast cancer, known BRCA1 or 2 mutation, or prior chest wall radiation
Burden of illness
There were approximately 22,700 new cases of breast cancer and 5,400 deaths from breast cancer in Canada during 2009. Incidence and case-fatality rates increase with age.
Intervention
Mammography (film or digital)
Recommendations
For women aged 40-49 we recommend not routinely screening.
(Weak recommendation; moderate quality evidence)
Basis of Recommendation
The likelihood of breast cancer is lower and the likelihood of false positive results on mammography is greater in younger women.
This recommendation places a relatively low value on a very small absolute decrease in breast cancer mortality and reflects concerns with unnecessary diagnostic testing and overdiagnosis (diagnosis of breast cancer that will not affect length or quality of life).
Women who place a higher value on a small reduction in breast cancer mortality and are less concerned about the potential harms may choose screening.
About 470 women aged 40-49 die of breast cancer in Canada each year.
To save one life
from breast
cancer over about
11 years in this
age group:
about 2100 women would need to be screened every 2 to 3 years
75 women would have an unnecessary breast biopsy
about 690 women will have a false positive mammogram leading to unnecessary anxiety and follow-up testing
For women aged 50-69 we recommend routinely screening every 2 to 3 years.
(Weak recommendation; moderate quality evidence)
Basis of Recommendation
Women who do not place a high
value on a small reduction in
breast cancer mortality and are
concerned about false positive
results of mammography and
overdiagnosis may decline
screening
About 900 women aged 50-69 die
of breast cancer in Canada each
year.
To save one life
from breast
cancer over about
11 years in this
age group:
about 720 women would need to be screened every 2 to 3 years
26 women would have an unnecessary breast biopsy
about 204 women will have a false positive mammogram leading to unnecessary anxiety and follow-up testing
For women aged 70-74 we
recommend routinely screening
every 2 to 3 years.
(Weak recommendation; low quality evidence)
Basis of Recommendation
Women who do not place a high
value on a small reduction in breast
cancer mortality and are concerned
about false positive results of
mammography and overdiagnosis
may decline screening
About 480 women aged 70-74 die
of breast cancer in Canada each
year.
To save one life
from breast
cancer over about
11 years in this
age group:
about 450 women would need to be screened every 2 to 3 years
11 women would have an unnecessary breast biopsy
about 96 women will have a false positive mammogram leading to unnecessary anxiety and follow-up testing
For every 1,000 women screened for about 11 years
About 5 women will unnecessarily undergo surgery for breast cancer
Details of recommended service
For women aged 50-74 we suggest screening every 2 to 3 years, which appears to preserve nearly all of the benefit of annual screening but reduces adverse effects, inconvenience to women and cost. No data from our review address the benefits of screening in women younger than 40 or older than 74 but benefit is likely lower than in women aged 50-74. Either digital or film mammography is acceptable. Screening with magnetic resonance imaging is not recommended.
Consider using your electronic health record to flag a screening reminder for patients aged 50 to 74 every 3 years; this can be particularly useful if you don't have a local screening program that generates automated reminders to patients
Special considerations
Certain ethnic groups may have higher (e.g. Ashkenazi Jews) or lower (East Asians) risk of breast cancer, which may increase or reduce the absolute benefit of screening, respectively. Rates of screening are low in Aboriginal populations, and further work is needed to determine how this can be improved.
Given the small absolute benefit of screening, benefit is uncertain in people whose life expectancy is substantially reduced by comorbid conditions. For people with comorbidity but normal or near-normal life expectancy, potential determinants of risk and benefit should be discussed.
Provincial and regional decision-makers should consider whether access to high quality screening facilities is adequate for people residing outside major centers.
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