CTFPHC · 2024

Breast cancer (update) — Draft recommendations (2024)

The draft recommendations and decision-making tools were open for public comment until August 30, 2024. Please note, the public comment survey is now closed.

The Canadian Task Force on Preventive Health Care would like to thank everyone who submitted comments on the draft recommendations and decision-making tools. We will include a summary of all feedback and how it was addressed in the final guideline. As some stakeholders will be interested in commenting on the modelling report, we will invite stakeholders to provide input on the report once it is available. The modelling data used for the draft recommendations is available in the draft report. The full modelling report will be based on updates to the OncoSim model that occurred after the draft recommendations were released on May 30, 2024. Revised estimates from this modelling exercise will be considered in the final guideline.

Decision-making tools

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Introduction

Breast cancer is a disease that touches many Canadians. It is the most common cancer and the second leading cause of cancer-related death among Canadian women. In 2024, it is estimated that 30,500 women will be diagnosed with breast cancer, representing 25.4% of all new cancers diagnosed (excluding non-melanotic skin cancers). It is also estimated that 5,500 will die from the disease, representing 13.5% of all cancer deaths among this group in 2024. Treatments for breast cancer are improving and offer more and more hope for women with breast cancer. Mortality from breast cancer is declining, from 41.7 deaths per 100,000 in 1989 to an estimated rate of 21.8 deaths per 100,000 in 2024.

We all want to find ways to continue to reduce the burden of this disease. That's why the Canadian Task Force on Preventive Health Care (Task Force) conducted a comprehensive evidence review on breast cancer screening, including recent observational studies, randomized controlled trials, and modelling. These were considered along with data from Statistics Canada and other sources to make sure we had the best, most recent and fulsome evidence for these draft recommendations.

The draft recommendations for breast cancer screening are for women* at average risk or at moderately increased risk**. They do not apply to those with a personal or extensive family history of breast cancer, genetic mutations that would increase breast cancer risk, or symptoms suggestive of breast cancer.

* People assigned female at birth.

** Moderately increased risk is defined here as 12 to 20% cumulative lifetime risk, and comprises women with dense breast category C or D and women with a moderate family history, defined as having one first-degree relative or two second-degree relatives diagnosed after age 50. Any more extensive family history or multiple risk factors (e.g., high breast density and a family history of breast cancer) may put an individual at high lifetime risk.

Draft recommendations

Breast cancer screening is a personal choice.

Women aged 40 to 74 should be provided information about the benefits and harms of screening to make a screening decision that aligns with their values and preferences. If someone in this age range is aware of this information and wants to be screened, they should be offered mammography screening every 2 to 3 years.

This information should be accessible and shared in absolute numbers. It should include how age, family history, race and ethnicity, and breast density (if known) may impact benefits and harms of screening. Tools are available on the Task Force website to support decision-making and discussions with healthcare providers.

Women aged 40 to 49

Based on the current evidence (trials, observational studies, modelling and a review on values and preferences), we suggest not to systematically screen with mammography. Because individual values and preferences may differ, those who want to be screened after being informed of the benefits and harms should be offered screening every 2 to 3 years (conditional recommendation, very low-certainty evidence).

Benefits and harms: In ages 40 to 49, we found that the harms may outweigh the benefits.
Patient values and preferences: Our systematic review showed that a majority of patients aged 40 to 49 may not weigh the benefits as greater than the harms, with important variability.
Race and ethnicity: There are data showing variability in incidence, mortality, subtype and stage at diagnosis (e.g., higher mortality in Black women in this age group).

Women aged 50 to 74

Based on the current evidence, we suggest screening with mammography every 2 to 3 years. Because individual values and preferences may differ, it is important that women aged 50 to 74 have information about the benefits and harms of screening to make their decision (conditional recommendation, very low-certainty evidence).

Benefits and harms: In this age group, the benefits may outweigh the harms.
Patient values and preferences: A majority of patients are likely to weigh the benefits as greater than the harms, with variability.
Race and ethnicity: Variability observed (e.g., higher mortality among First Nations and Métis women aged 60 to 69).

Women aged 75 and above

Based on the current evidence (observational studies and modelling; no trials available), we suggest not to screen with mammography (conditional recommendation, very low-certainty evidence).

Benefits and harms: There is a lack of information; there is concern that harms outweigh benefits beyond age 74.
Values and preferences: A majority of patients aged 75 and above are likely to weigh the benefits as greater than the harms, with variability.
Race and ethnicity: Lack of data.

Recommendations on supplemental screening

For women with moderately increased risk due to high breast density(categories C and D), we did not find any evidence on the benefits of supplemental screening for outcomes important to patients. Therefore, we do not suggest the use of MRI or ultrasound as supplementary screening tests (conditional recommendation, very low-certainty evidence). If interested in screening, these women should refer to the recommendation that corresponds to their age group.

For women with moderately increased risk due to family history of breast cancer, we did not find any evidence on the benefits of supplemental screening. Therefore, we do not suggest the use of MRI or ultrasound as supplementary screening tests (conditional recommendation, very low-certainty evidence). If interested in screening, these women should refer to the recommendation that corresponds to their age group.

What do the recommendations mean?

If you are a patient

Screening is a personal choice. Make sure you have the information about the benefits and harms in order to make a decision that aligns with your values and preferences. Tools are available on the Task Force website. These recommendations are for people at average to moderately increased risk without breast symptoms. If you have symptoms (e.g., a lump), consult a healthcare provider.

If you are a primary care provider

For a woman aged 40 to 74 considering screening, provide information in absolute numbers about the potential benefits and harms as part of shared decision-making. Although the recommendation favours screening for people aged 50 to 74, it remains important to provide this information. If she decides to participate, offer her mammography screening.

For screening programs

Whether people access programs through self-referral, invitation, or a healthcare provider, they should receive clear information in absolute numbers. As a quality measure, programs should track the number of women able to make an informed decision and gather data related to race and ethnicity.

Additional Documents

Who worked on these recommendations?

Voting members – Breast Cancer Screening Working Group

Guylène Thériault, MD
Nathalie Slavtcheva, NP
Jennifer Flemming, MD
Kate Miller, MD
Scott Klarenbach, MD
Ashraf Sefin, MD

Collaborating members of the Canadian Task Force

Eddy Lang, MD
Patricia Li, MD
Gail Macartney, NP
Donna Reynolds, MD
Henry Siu, MD
Keith Todd, MD

Clinical and content experts (non-voting)

Alexandra Easson, MD (surgeon)
Derek Muradali, MD (radiologist)
Michelle Nadler, MD (oncologist)
Jonathan Sussman, MD (radiation oncologist)

Patient partners

Dawn Barker
Samira Chandani
Siobhan Grennan

Global Health and Guidelines Division, Public Health Agency of Canada

Heather Limburg
Laure Tessier
Greg Traversy
Leila Esmaeilisaraji, MD
Chantelle Garritty
Casey Gray
Mona Hersi
Melissa Subnath
Julie Wu
Allison Yeung

Evidence review and synthesis centres

University of Alberta: Alberta Research Centre for Health Evidence

Jennifer Pillay
Samantha Guitard
Sholeh Rahman
Sabrina Saba
Ashiqur Rahman
Liza Bialy
Nicole Gehring
Maria Tan
Alex Melton
Lisa Hartling

University of Ottawa

Alexandria Bennett
Nicole Shaver
Niyati Vyas
Faris Almoli
Robert Pap
Andrea Douglas (patient partner)
Taddele Kibret
Becky Skidmore
Martin Yaffe (clinical expert)
Anna Wilkinson, MD (clinical expert)
Jean M. Seely, MD (clinical expert)
Julian Little
David Moher

Knowledge translation team

Knowledge translation program staff at Unity Health Toronto

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