The number of deaths from breast cancer is on the decline, but new data out of the U.S. shows the prevalence of cases among women under 50 years of age is rising.
That has advocates for breast cancer screening once again urging change in Canada.
The study, published in CA: A Cancer Journal for Clinicians on Tuesday, found the number of deaths declined by 44 per cent between 1989 and 2022.
“I think that’s amazing,” Kimberly Carson, CEO of Breast Cancer Canada, told Global News. “That’s why we work as hard as we do in research to be able to change those statistics.”
There were roughly 518,000 fewer deaths overall during that time span, though it notes certain demographics have not seen the same decline. American Indian/Alaska Native women saw no reduction in mortality, while Black women have a 38 per cent higher mortality than white women, despite a five per cent lower incidence rate.
In fact, the study notes this group has the lowest survival rate of any racial and ethnic group for every breast cancer subtype and stage of the disease, except for the “localized-stage,” at which they are 10 per cent less likely than white women to be diagnosed.
Even with these discrepancies, however, the study says the decrease in the number of deaths overall is in large part due to advances in treatment and earlier detection through screening.
“The sooner that we catch it, the better the outcome,” Carson said. “Certainly screening is obviously a huge, huge priority because we can catch it at Stage 0, Stage 1 … your chance of surviving breast cancer is almost 100 per cent.”
According to the study released Tuesday, breast cancer incidence has been rising by one per cent each year between 2012 and 2021.
The study noted the rising trend was mainly confined to hormone receptor-positive disease, in which breast cancer cells are found to have receptor proteins that estrogen and progesterone attach to, stimulating cancer to grow.
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In addition, the study notes associated risk factors such as increased excess body weight and continued decline in the fertility rate also contributed — the Canadian Cancer Society notes not becoming pregnant at all increases the risk for breast cancer, while “the more children a woman has, the greater the protection against breast cancer.”
The data found various differences depending on race and ethnicity, with Asian-American and Pacific Islander women seeing the fastest increase. Those under 50 saw a higher rise of 2.7 per cent compared with 2.5 per cent for those 50 and older.
Among white women, there was a 1.4 per cent annual increase under 50, compared with 0.7 per cent in those 50 and older.
The increase in cases among younger women is just the latest in a series of studies showing various types of cancers are on the rise in younger adults, with a study published in The Lancet in July showing higher incident rates in generation X and millennials for 17 of 34 cancer types, including breast, pancreatic and gastric forms.
Early detection is a key way to get ahead of the disease or treat it early, but that is proving to be a potential issue north of the border, where data suggests similar trends.
A study published in April found a similar increase among Canadian women, especially among those under 50.
There were an average 5.7 cases per 100,000 people among those in their 20s annually between 2015 and 2019, up 45.5 per cent from the number seen between 1984 and 1988.
There was also a 12.5 per cent increase between these two periods for those in their 30s, and 9.1 per cent for those in their 40s.
The Canadian Task Force on Preventative Health Care in May kept its guidance in place, with regular screening mammography only recommended for patients between the ages of 50 and 74, though women in their 40s can request it.
The task force said its position was due to concerns of over-diagnosis and unnecessary biopsies, but some experts called it “outdated and flawed,” and Health Minister Mark Holland announced he was opening an external review into the task force amid its decision.
The task force’s move came even as the U.S. lowered its own recommended age to 40, and Ontario said screening would be expanded this fall.
Carson said the U.S. study shows that the rate among young women is rising and the lack of movement in Canada is “unfortunate.”
“It saves lives if we catch it earlier and it’s also less cost-intrusive onto the system if we can catch it earlier,” she said.
A recent Angus Reid poll last month, commissioned by the organization, found 94 per cent of Canadians felt screening should start at age 40, but more than 27 per cent reported neither they nor a loved one have been screened and depending on when cancer is caught, it changes the treatment.
“If you’re diagnosed at zero or Stage 1, you may just do lumpectomy and radiation and off you go, as opposed to let’s say Stage 3, where you’re looking at perhaps chemotherapy, surgery, more chemotherapy, radiation; it’s certainly a longer journey,” Carson said.
According to the Canadian Cancer Society, there are things you can do though to reduce your risk like limiting alcohol intake, being physically active and following screening guidance.
— with files from Global News’ Katie Dangerfield
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