Thursday's report by the Canadian Institute for Health Information showed differences in the use of all surgical treatments for breast cancer. About 22,000 women in Canada have surgery for breast cancer each year.
Most of the breast cancer patients studied were treated for invasive disease. (iStock)
"These findings raise questions about how Canadian women are exercising their treatment options and the resultant quality of care," the report's authors concluded, based on data from 2007–2008 to 2009–2010.
Mastectomy rates ranged from 69 per cent in Newfoundland and Labrador to 26 per cent in Quebec.
The differences decreased only slightly when age, income and travel time to a cancer centre were considered, the institute said.
Generally, clinical practice guidelines recommend breast conserving surgery, also called lumpectomy, and radiation therapy for the majority of women with breast cancer. Lumpectomy and radiation are less invasive and are associated with fewer complications with similar survival to mastectomy.
Dr. Geoff Porter, a professor of surgery at Dalhousie University in Halifax, called the report an important step in understanding differences in breast cancer surgery.
"We can only really understand where we're going if we know where we are," Porter said. "I think that's just very valuable when you think about optimizing the quality of breast cancer care. We need to know those patterns and trends so that we can see whether they're changing."
Porter said that the high rates of mastectomies and re-excisions or repeated surgeries if lab tests show that residual tumours may be present, could be higher in Newfoundland and Labrador because of differences in how the surgeries are counted in that province.
In many areas in Canada, core biopsies with a needle are used to make a diagnosis. In Newfoundland and Labrador, the tumour itself may be removed for the diagnosis and that surgery could be counted as the first one, he said.
Porter said the report offers a powerful way to look at breast cancer in the population. The tradeoff is that clinical data, such as the size of tumour and its stage, weren't included.
The type of surgery can also vary with income. In the report, women living in the least affluent areas had the highest rates of mastectomy. Long courses of radiation are generally recommended after lumpectomies and travel time appeared to significantly reduce use of less-invasive surgery, the authors said.
A third of mastectomies in Ontario were done as day surgeries but fewer than two per cent in Alberta and Saskatchewan were done that way.
"The extent of this variation raises interesting questions regarding the organization of care and resources issues."
The report was prepared by CIHI and the Canadian Partnership Against Cancer.