A University of Calgary epidemiologist is using data from Ontario Health Study (OHS) participants to explore how environmental or lifestyle factors could be associated with breast cancer in younger women.
Dr. Darren Brenner recently gained approval to study the de-identified data for female participants who were ages 35 to 50 and cancer-free at the time they joined the OHS. Questionnaire data from the OHS will be combined with Ontario Cancer Registry data to focus his work on those who have subsequently had a cancer diagnosis since joining the OHS.
Comparatively little is known about the risk factors for young-onset breast cancer, Brenner noted in his application to use OHS data. Inherited genetic mutations play a role, but generally only account for 5% to 10% of young-onset cases, suggesting lifestyle or environmental factors may contribute to the development of breast cancer in younger women. The role of obesity needs further study, he noted, as recent studies suggested a decreased risk for breast cancer in younger women with obesity.
Younger women diagnosed with breast cancer tend to have poorer survival rates because they are not routinely screened, and so tend to have an already-advanced stage of cancer once they are diagnosed.
Breast cancer remains the most commonly diagnosed cancer among Canadian women. Though the number of cancer diagnoses in older women has gone down over the last 25 years, the number of women under age 50 who receive a breast cancer diagnosis has increased. According to the Canadian Cancer Society, breast cancer accounts for 23% of diagnosed cancers in Canadians aged 30 to 49. On a positive note, female breast cancer death rates have decreased an estimated 48% since they peaked in 1986.
In addition to using questionnaire data and blood samples from OHS participants, Dr. Brenner is also pulling similar data about British Columbian and Albertan women, through the Canadian Partnership for Tomorrow Project, Canada’s largest population cohort study.
Dr. Brenner and his team will examine the impact of lifestyle, environmental, and reproductive factors, family and medical history, as well as breast cancer screening protocols, on the risk for breast cancer in women under 50.
Results from their investigation could improve researchers’ understanding of young-onset breast cancer causes and could lead to improved prevention strategies.
Read more about Dr. Brenner and his other research projects in this article: ‘Research Rockstar’
 Canadian Cancer Statistics 2019 p. 14
 Canadian Cancer Statistics 2019 p. 7