Canada's breast cancer screening guidelines fail to address racial and ethnic disparities

University of OttawaNov 5 2024

Canada's current national screening guidelines for breast cancer are less appropriate for women of certain race and ethnicity groups since they are diagnosed at younger ages with more advanced stages of the disease. The new findings from a University of Ottawa research team underscore the urgent need to reevaluate screening guidelines to account for racial and ethnic differences and ensure equitable healthcare access, including earlier screening, to improve outcomes for all women. 

Breast cancer characteristics and outcomes in Canada related to race and ethnicity are not currently documented. This new study has found that Canadian women who did not identify as White had an earlier peak age of breast cancer diagnosis and higher proportions of cases diagnosed under age 50. They also have an earlier peak age of death, dying on average seven years earlier.

Key findings

The study, which linked census data with the Canadian Cancer Registry to assess breast cancer cases, was conducted by a team of researchers led by Dr. Anna Wilkinson and Dr. Jean Seely along with Carmina Ng and Larry Ellison from Statistics Canada. 

Published in The Oncologist, key findings include:

• A Black woman in her 40s faces a breast cancer mortality rate that is 40% higher compared to White women of the same age group.
• First Nations and Métis women in their 60s face mortality rates 20% to 50% higher than White women of the same age groups, respectively.
• The peak age of breast cancer diagnosis was 65 for White women, compared to ages 42-60 for women of other race and ethnicity groups.
• About 1/3 of breast cancer cases were diagnosed before age 50 in ArabInuit, Korean, West Asian and multiethnic women compared to 16% in White women.
• White women have higher rates of hormone-positive breast cancer, a subtype associated with better outcomes, while Black women had double the proportion of aggressive triple-negative breast cancer, which has much poorer survival rates. (Five-year survival for stage III triple-negative breast cancer is only 74%, and just 7% for stage IV.)

Early screening

"This study highlights the importance of screening starting at age 40 for individuals who are typically diagnosed with breast cancer at younger ages. Screening starting at age 50 systematically disadvantages women of race and ethnicity groups other than White, potentially leading to more advanced disease at diagnosis and, in the case of Black women, possibly higher mortality," said lead author Dr. Wilkinson, Associate Professor in the Faculty of Medicine. 

"Moreover, elevated mortality rates among Metis and First Nations women mandate an examination of barriers to healthcare these women face across the cancer continuum-;from screening to diagnosis to treatment."

Addressing care gaps

Despite provincial advances – Ontario now includes women aged 40-49 in their organized screening program – national guidelines will continue to influence family physicians to recommend against screening when patients seek their guidance, according to researchers, potentially leading to missed opportunities for early detection among women of color.

The lead authors from uOttawa – whose previous research touches on screening guidelines and rising breast cancer rates – see updated cancer data collection as the best aid for understanding the underlying reasons for mortality disparities and to address gaps in cancer care.