Building on earlier research which suggests that cancer incidence and cancer-related outcomes can vary, depending on where people live, Statistics Canada researchers have published their work looking at geographic variability in the incidence and mortality of breast cancer among females in Canada.
The study found that between 2010 and 2020, the invasive breast cancer age-standardized incidence rates (ASIRs) was 140.1 per 100,000 females annually, “with marked geographic and community variation,” they write. “Mean age at diagnosis was 62.7 years.”
The summary report, Geographic variation in female breast cancer incidence and mortality in Canada, found that ASIRs were significantly higher in Quebec and Alberta, when compared to Ontario and significantly lower in New Brunswick, Manitoba, Saskatchewan, British Columbia and Nunavut.
The study also looks at community sizes – those in communities with between 500,000 and 1,499,999 people had a significantly higher ASIR of 142.3 per 100,000.
Nationally, the mean age at diagnosis varied significantly across the country, coming in lower in Nunavut (54.2 years), the Northwest Territories (56.7 years) and Alberta (61.2 years), compared with Ontario (62.5 years). “Other provinces had significantly higher mean ages at diagnosis,” they write. “In general, the mean age at diagnosis increased with decreasing community size.”
The report also notes that regions with relatively higher breast cancer incidence rates do not necessarily also experience relatively higher breast cancer mortality rates.
Notably, in a review of existing research, the report’s authors point to a U.S. study which also notes significant geographic variability in incidence trends, before going on to suggest that place-based factors be incorporated into risk prediction algorithms alongside other established risk factors including age, ethnicity and genetics.
“The geographic variability in the present study also supports considering the impact of geography and place-based risk for breast cancer incidence and mortality in Canada,” they write. The current findings indicate that where a person lives may have an important impact on their cancer-related risk.”
