The proportion of advanced breast cancers in women aged 50 to 59 is lower in provinces that perform annual mammograms in their 40s, a new study has found.
Provinces that have ended their screening program for 40 to 49 year olds have seen the number of stage 4 cancers in women aged 50 to 59 jump 10.3% in six years.
This is according to the study of a research team from the University of Ottawa and the Ottawa Hospital, published in the journal Current Oncology and released on Wednesday.
At the same time, there is a lower proportion of stage 2, 3 and 4 breast cancers in women aged 40-49 and stages 2 and 3 in women aged 50-59 in provinces that carry out annual screening in 40-year-olds.
“This study is the first in Canada to confirm the benefits of screening from the age of 40 in women aged 50 to 59,” said Dr. Anna Wilkinson, co-lead author of the study and associate professor at the University of Ottawa Faculty of Medicine.
“Fifties who have not been screened in their forties have breast cancer at more advanced stages. They therefore require more intensive treatments and their prognosis is less favorable, compared to women who were diagnosed at an earlier stage,” she explained.
This research has also shown a lower survival rate in those whose cancer was diagnosed at an advanced stage. The five-year survival rate reaches 99.8% for stage 1 cancers, compared to only 23.2% for cancers diagnosed at stage 4. “Our findings are in line with the recent update of guidelines from the National Comprehensive Cancer Network, in the United States, which recommends starting annual mammograms as early as age 40 in women at average risk,” said Dr. Jean Seely, Chief of the Ottawa Hospital Breast Imaging Service. and Professor in the Faculty of Medicine at the University of Ottawa.
Today, only Nova Scotia, Prince Edward Island and the Yukon send annual reminders to women in their 40s to be screened.
The study analyzed data from the Canadian Cancer Registry on 55,490 women aged 40 to 59 who were diagnosed with breast cancer between 2010 and 2017.
