Women are 70% more likely to survive stage 1 breast cancer than stage 4, and new research shows that earlier screening could catch breast cancer earlier, increasing their survival rate.
A study out of the University of Ottawa found that women between the ages of 40 and 49 who were annually screened for breast cancer had lower proportions of advanced breast cancer than 50- to 59-year-old women who were not given early routine mammograms. These results are based on the 2011 updated breast cancer screening guidelines, which were implemented in some, but not all, Canadian provinces.
“This is the first Canadian study to show that screening policies for women [aged] 40 to 49 impact women [aged] 50 to 59,” said co-lead author Anna Wilkinson, MD, an Associate Professor in the Faculty of Medicine at the University of Ottawa, in a press release. “Women who are not screened in their forties are presenting with later stage breast cancer in their fifties. This means more intensive treatment and a worse prognosis for these women than if their cancers were diagnosed at an earlier stage.”
Wilkinson worked with Jean Seely, MDCM, FRCPC, head of breast imaging at the Ottawa Hospital and Professor at the University of Ottawa’s Faculty of Medicine. The duo reviewed data from the Canadian Cancer Registry and examined the impact of the 2011 Canadian breast cancer screening guidelines.
The new guidelines changed the recommended age for breast cancer screening from women aged 50 to 59 to women aged 40 to 49. The researchers analyzed 55,490 women from the database, either between the ages of 40 to 49 or aged 50 to 59, who were diagnosed with breast cancer between 2010 and 2017.
The team then examined the incidence changes by stage. Stage 1 incidence decreased by 13.6% since the guideline changes, whereas stage 2 incidence increased by 12.6% among women in their forties, but only 3.1% for women in their fifties.
In Canadian provinces not regulating screening programs for 40- to 49-year-old women, stage 4 breast cancer increased by 10.3% in 50- to 59-year-old women over the 6 years that they were studied.
The 5-year survival rate for stage 1 breast cancer is 99.8% vs. 23.2% for stage 4 diagnoses, according to the study. However, early diagnosis could lead to increased survival rates and decreased mortality, according to researchers.
“This is a great example of the benefit of using Canadian Cancer Registry data housed at Statistics Canada to take advantage of studying the effect of different policies regarding ages to start screening. Our findings align with recently updated USA National Comprehensive Cancer Network guidelines that recommend annual screening mammography for average risk women beginning at age 40,” Seely said in the press release.
Despite new evidence from this study and others, the Canadian jurisdiction is not enforcing polices to screen at a younger age. Currently, only Nova Scotia, Prince Edward Island, and Yukon provinces screen for breast cancer for women in their forties.
“Further work will be needed to determine whether finding these cancers at an earlier stage translates into fewer fatal breast cancers and improved long-term outcomes,” Seely added in the press release.
Study shows annual screening before age 50 leads to lower proportions of advanced breast cancer. University of Ottawa. August 10, 2022. Accessed August 22, 2022. https://www2.uottawa.ca/about-us/media/news/study-shows-annual-screening-age-50-leads-lower-proportions-advanced-breast-cancer