2024 Breast Cancer Screening Guideline Update

Q&A with Dr. Guylène Thériault, a family physician, teacher of evidence-based medicine and Canadian Task Force on Preventative Health Care Chair.

The Task Force will issue draft recommendations this spring on screening for breast cancer screening. 

Q: Why are national guidelines important and what role do they play in Canadian health care?

  • National clinical guidelines provide critical guidance for primary healthcare providers and their patients. Clinicians seek trustworthy, easy-to-understand guidance and tools to share with their patients to help them understand screening and other preventive care interventions. Our guidelines provide evidence-based recommendations for family physicians, nurse practitioners and other primary care providers. We look at the best evidence available as well as information on patient values and preferences on topics such as screening for cancers, thyroid dysfunction, and chronic health conditions, and interventions aimed at prevention such as tobacco cessation.
  • Primary care has a unique role in providing preventive health. Their comprehensive and holistic care for patients allows them to understand potential benefits and harms of medical interventions, particularly those offered to otherwise healthy patients. This differs from a specialist perspective whose patients present with the disease in question or symptoms that warrant investigation.

Q: Who is involved in creating the guideline?

  • For each guideline, the Task Force relies on subject matter experts and patient input. The breast cancer screening guideline update includes four content experts (a clinical oncologist, a radiation oncologist, a surgical oncologist and a radiologist), and three patient partners with lived experience.
  • This is in addition to the Task Force, which currently includes 6 family physicians, 4 specialists and 2 nurse practitioners who have additional expertise in guideline creation. As members of the Task Force, they do not have ties to industry, specialty organizations, nor financial conflicts of interest.
  • We also rely on research teams with specialized skills in evidence synthesis.

Q: What new approaches has the Task Force adopted for the 2024 breast cancer screening guideline update?

  • In the past, we have relied largely on RCTs, which are the gold standard for understanding the effects of healthcare interventions. However, for breast cancer screening, most of the RCTs are older. To ensure we include more recent evidence, we expanded our review to include recent observational trials as well as RCTs and modelling. We considered these study types with data from Statistics Canada and other sources to ensure we had the best, most recent evidence. 
  • We also included 3 patient partners from the beginning on the working group and engaged the TF-PAN (Task Force Public Advisors Network) to understand what patients want to know.

Q: How do you balance evidence against real-world experiences of people concerned about or experiencing breast cancer?

  • Breast cancer is a disease that touches many Canadians. We have all heard heart-breaking stories and want to find ways to reduce the burden of this disease.  It’s important to look at the evidence to understand what are the benefits and harms of screening as we can’t recommend something if the benefits do not clearly outweigh the harms. 
  • We do this regularly in life – we weigh the pros and cons of what cell phone plan is best, do we buy a house now or wait until interest rates drop? 
  • With scientific evidence, it’s not always easy to interpret. In life we like to think of things in black and white but with evidence, it is often less clear and more “grey”. Think of those reports we hear that coffee is good for us, then another that it’s bad for us. This holds true for many diseases and interventions. While evidence is often changing, we need scientifically sound data to understand what will hold true and what will not.

Q: Who are the recommendations for?

  • They are for women (people assigned female at birth) at average or moderately increased risk of breast cancer. This includes people with dense breast category C or D or moderate family history (with no more than one first degree or two second degree relatives diagnosed after 50).
  • The recommendations do not apply to those with a personal or extensive family history of breast cancer, and genetic mutations that would increase breast cancer risk, or symptoms suggestive of breast cancer.
  • We want to make it clear that if anyone has a symptom, like a lump, they should talk to a health care provider to investigate. If someone has symptoms, a mammogram is not done for screening but rather diagnostic testing.

Q: There is a lot of debate about breast cancer screening and some people have expressed criticism of the Task Force. What are the key misperceptions about the current guideline update?

  • Critique and feedback help push us to do our best. We don’t expect everyone to agree with us, but we are confident that we are systematically following the evidence and will produce the most appropriate recommendations for Canadian primary care providers and their patients.
  • A criticism is that we don’t use experts in guideline creation. This is false. For each guideline we involve subject matter experts – there are 4 involved with the breast cancer update. Also, Task Force members are experts in their fields – family physicians and nurse practitioners, leaders in emergency medicine, pediatrics and other specialties. Since the main users of our guidelines are primary care clinicians and their patients, a primary care perspective is important. 
  • There is confusion around the difference between screening and diagnostic testing. Screening is done in otherwise healthy people who don’t have symptoms. Diagnostic testing occurs if someone has a symptom such as a breast lump. For this, they should talk to a health care provider as that is not screening.  
  • Another comment we’ve heard is that we are only looking at the older RCT evidence. On the contrary, this guideline review includes recent observational trials, including one from 2020 and a commissioned modelling exercise from 2023/24. We have included more than 165 studies in the analysis, winnowed down from 1000s using pre-defined criteria. 
  • Sometimes someone will point out studies that support their personal position. It’s important to understand that you can’t pick and choose studies because they support your perspective; we have looked at them all, through the same lens.

Q: What would the health care landscape look like if national guidelines did not exist?

  • There are massive amounts of information in the world now. Clinicians are busy, and there is a shortage of primary care professionals. They need unbiased, easy-to-use, trustworthy evidence-based guidance to help them care for their patients. We need to make it easy for them to provide evidence-based care. Many associations produce their own guidelines, but these may have a local or specialty focus. We need unbiased guidelines that everyone across Canada can trust.


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