The Canadian Task Force on Preventive Health Care has released an updated breast cancer screening guideline placing emphasis on shared decision-making between women and their health care providers. This is meant to support women to decide whether to undergo screening or not based on their own values and preferences.
In Canada, most women 50 years and older who are not at elevated risk are invited for mammography screening for breast cancer and face a decision about whether to participate, according to Dr Ainsley Moore Vice-Chair of the Task Force.
“A review conducted for this guideline on women’s values and preferences about breast cancer screening suggests that many women aged 40 to 49 years would choose not to be screened if they were aware of outcomes for their age group,” said Dr Moore in a press release.
On the other hand, many women aged 50 years and older would choose to screen given the more favourable balance of benefits and harms. Some women of this age may choose not to be screened based on their individual values and preferences around the benefits and harms of screening.
Breast cancer screening using mammograms identifies breast cancer earlier and leads to a reduction in the risk of breast cancer mortality; however, it also leads to known harms including false-positive results, further testing and possible breast biopsy, as well as overdiagnosis resulting in unnecessary treatment and potential associated complications.
The most recent evidence examined by the Task Force continues to show a close balance between these potential benefits and harms.
The Guideline reflects the growing importance of shared decision-making between patients and physicians in preventive health screening, especially in situations like this where the balance between potential benefits and harms is not certain.
Meanwhile, screening is recommended in women aged 50-74.
The Guideline, developed by the Task Force, an independent body of primary care and prevention experts, has been published in the Canadian Medical Association Journal (CMAJ).
Other screening modalities
The Task Force recommends not using magnetic resonance imaging (MRI), tomosynthesis or ultrasound to screen for breast cancer in women not at increased risk. (Strong recommendation; no evidence)
We recommend not performing clinical breast examinations to screen for breast cancer. (Conditional recommendation; no evidence)
It recommends not advising women to practice breast self-examination to screen for breast cancer. (Conditional recommendation; low-certainty evidence)
There was an absence of evidence on clinical outcomes of screening by magnetic resonance imaging, ultrasound, digital breast tomosynthesis or clinical breast examination, and there was evidence that performing breast self-examination has no impact on breast cancer mortality.
However, the Task Force noted that better-quality evidence is needed on the impact of breast cancer screening for women of all ages. Additional studies on Canadian women’s values and preferences for screening that are based on accurate estimates of both benefits and harms, conducted in a transparent and easily comparable manner, would help guide future recommendations.
This clinical practice guideline has been endorsed by the Nurse Practitioners’ Association of Canada (NPAC).
The Canadian Task Force on Preventive Health Care was established to develop clinical practice guidelines that support primary care providers in delivering preventive health care. The mandate of the Task Force is to develop and disseminate clinical practice guidelines for primary and preventive care, based on a systematic analysis of scientific evidence.