Women diagnosed with early-stage breast cancer can expect to become long-term survivors of the disease, according to a recent study.
The study, published Tuesday by the BMJ, found the average risk of dying from breast cancer in the five years after an early-stage diagnosis has fallen to five per cent from 14 per cent since the 1990s.
The study included 512,447 women diagnosed with early breast cancer (meaning it had not spread outside the breast) in England from 1993 to 2015.
“We followed them for up to 20 years and we found the prognosis for women with early breast cancer has improved substantially during the past 20 years,” Carolyn Taylor, professor of oncology at the University of Oxford and lead author of the study, told Global News.
“You can use the data to estimate the risk of breast cancer death by five years. And I think some women don’t want to know their prognosis. But for some women, this will be really reassuring. It can help people to plan ahead, to plan their lives,” she said.
Breast cancer is the most common type of cancer in women in Canada and the second leading cause of cancer deaths in Canadian women, according to the Canadian Cancer Society.
The national cancer charity estimates that about one in eight Canadian women will develop breast cancer during their lifetime and one in 34 will die from it.
The five-year survival rate for breast cancer in women in the country is 89 per cent, meaning a vast majority of women diagnosed with breast cancer will live for at least five years, the society stated on its website.
While Canada does not specifically track survival rates based on the stages of breast cancer diagnosis, the Canadian Cancer Society said that survival outcomes vary depending on the stage of the disease, and early detection generally results in better outcomes.
“It is a trend that we’ve been seeing for years and years. So it’s lovely to see some really solid data coming out of the U.K.,” said Kimberly Carson, CEO of Breast Cancer Canada. “Canada and the U.K. are very similar in demographics and so it’s great news for Canada because it’s confirmatory data that we’ve been seeing for a number of years.”
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“So that’s a two-thirds reduction,” Taylor said.
The researchers of the BMJ study found that annual breast cancer mortality rates and risks decreased with increasing calendar periods. The five-year breast cancer mortality risk was 14.4 per cent for women with a diagnosis made between 1993 and 1999 and 4.9 per cent for women with a diagnosis made between 2010 and 2015.
She noted that the study only collected data on women who died of breast cancer and didn’t look at cancer recurrence.
“But what we were able to say in our study was the risk of dying from breast cancer has reduced substantially during the past 20 years,” she said.
Why have breast cancer deaths dropped?
There are many different reasons explaining why breast cancer prognosis has improved over the past 20 years, Taylor said.
“Breast cancer care has improved considerably and there are many different aspects to that. One is that chemotherapy is better. We now use better chemotherapy drugs than we did 20 years ago,” she explained.
Taylor said that radiotherapy has significantly improved compared to previous decades. Additionally, she said there has been an increase in public awareness about the disease, resulting in more women undergoing breast cancer screening.
Carson believes the high rate of survival for women with breast cancer also has a lot to do with research and precision medicine.
“Precision medicine is really personalized medicine. We know that each person that has a breast cancer diagnosis is going to respond differently. We cannot do one size fits all anymore,” she said.
An example of that is newly developed targeted therapy for breast cancer, which are medications that specifically zone in on certain molecules involved in the growth and spread of breast cancer cells. The therapies interfere with the cancer cell’s ability to grow and divide while minimizing damage to healthy cells.
Carson added that although the rate of screening has increased over the years, organizations like Breast Cancer Canada are urging the federal government to lower the age from 50 to 40.
This comes more than a month after a U.S. health task force recommended women get screened for breast cancer 10 years earlier than the current mammogram recommendation of 50.
In Canada, regular screening mammography is only recommended for patients between the ages of 50 and 74.
But Carson said lowering the screening age to 40 could save more lives, as studies have found those who have mammograms starting at age 40 are 40 per cent less likely to die of breast cancer than women who don’t have mammograms.
'Needs to be zero'
The advances in breast cancer care that have happened in England have been mirrored by other countries, like Canada, Taylor said.
“The changes in treatment have happened in European countries, in Canada and the U.S. as well. So I would expect these improvements in patients diagnosed in England to also be reflected by improvements in other countries,” she explained.
Canada’s breast cancer mortality rate peaked in 1986 and has been declining since, according to the Canadian Cancer Society, adding the reduction in death rates likely reflects the impact of screening and improvements in treatment for breast cancer.
“Before going into the pandemic, your survival rate past five years is almost 90 per cent,” Carson said. “And now with the confirmatory study out of the U.K. mortality rate (could be) at least five per cent, that’s even a better outcome than we could have ever hoped for.”
But she added that a five per cent mortality rate is “still not good enough yet.”
“We still have more to do,” she said. “That five per cent needs to be zero so that it’s no longer a death sentence, that it’s something that you live with, something like diabetes.”
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