Breast cancer rates creeping upward

Breast cancer is the most common cancer among Canadian women. In 2025, 1 in 8 women were expected to be diagnosed with breast cancer in their lifetime, and 1 in 35 expected to die from the disease. 

Breast cancer rates among women have been inching up by about 0.2% per year for nearly two decades. The incidence of breast cancer has increased for all age groups, particularly among women under the age of 50 years. 

For women aged 20 to 29 years, the breast cancer incidence rate per 100,000 women rose from 3.6 in 2001 to 6.1 in 2019. For women aged 30 to 39 years, the incidence rate per 100,000 women rose from 38 to 42, while for those aged 40 to 49 years, it rose from 131 to 141.

Breast cancer has multiple subtypes, some being more aggressive than others. 

Triple-negative breast cancer is one of the more aggressive subtypes. From 2012 to 2017, it accounted for approximately 1 in 10 cases overall, 1 in 5 cases among women diagnosed under the age of 40 years and 1 in 5 cases among Black women.

A recent study found significant geographic differences in both breast cancer diagnoses and deaths among females in Canada, underscoring that where people live may influence their cancer risk and outcomes. 

Using data from the Canadian Cancer Registry and national death records, the study tracked invasive breast cancer incidence from 2010 to 2020 and breast cancer mortality from 2010 to 2022. 

Overall, after age standardization, the breast cancer incidence rate averaged 140 cases per 100,000 females each year, while the breast cancer mortality rate stood at 28 deaths per 100,000 females.

However, these figures mask wide variation across provinces, territories and communities. Cancer incidence rates were highest in certain urban centres with large immigrant and racialized populations, as well as in some rural regions in Quebec, Ontario and the Prairies. In contrast, rates were lowest in large metropolitan areas, such as Montréal, Toronto and Vancouver. 

Most breast cancer cases from 2010 to 2020—about three-quarters—were diagnosed at earlier stages (stages 1 and 2). However, stage-specific incidence varied by geography, perhaps suggesting differences in screening, access to care and underlying risk factors.

Conversely, mortality patterns followed a different geographic picture. Death rates from breast cancer were highest in rural eastern regions and lowest in large urban centres. Such differences may be due to potential disparities in screening behaviour, treatment access and follow-up care.

Mammograms can help detect breast cancer; however, screening practices vary across provinces and territories. 

In 2024, the Canadian Community Health Survey found that 79% of females aged 50 to 74 years living in the provinces reported having had a mammogram within the past three years, little changed from 2017 (78%).

Differences in breast cancer screening participation among women aged 50 to 74 years exist between the provinces. In 2024, mammogram rates among women aged 50 to 74 years ranged from just over four in five in Alberta and Ontario to two in three in the Maritimes.

In 2024, one in three women (32%) reported that the reason they did not have a mammogram within the past three years was because they did not think it was necessary.

Among women diagnosed with breast cancer from 2010 to 2017, the five-year net survival rate was 99.8% at stage 1, 91.9% at stage 2, 74.0% at stage 3 and 23.2% at stage 4.

Simulation studies using the microsimulation model OncoSim have shown that increasing participation in breast cancer screening or altering the frequency or age-eligibility of screening could result in earlier detection of breast cancer and fewer breast cancer-related deaths.