Surgical care for breast cancer in Canada varies substantially across the country according to the province or territory in which a woman lives, according to an article in CMAJ Open.

Breast cancer surgery is the most common treatment for early-stage breast cancer. For most women, long-term survival with breast-conserving surgery (lumpectomy combined with radiation therapy) is comparable to mastectomy.

To better understand breast cancer surgery trends in Canada, researchers looked at data from the Canadian Institute for Health Information (CIHI) on 57 840 women in every province and territory who had breast cancer surgery between 2007/08 and 2009/10. Most, 98%, had surgery for invasive single breast cancer. The highest mastectomy rate - 48% - was in the youngest (under 49 years) and oldest (over 70 years) age groups compared with middle-aged women (40%). Women in Quebec had the lowest rates of mastectomy (26%) compared with those in Newfoundland and Labrador, who had the highest rates (69%).

Increasing distance from radiation facilities (usually located in urban areas) was correlated with higher rates of mastectomies. Socioeconomic status also affected mastectomy rates, with the most affluent women less likely (39%) to undergo the procedure compared with the least affluent (49%).

"As well as describing breast cancer surgery rates from a pan-Canadian perspective, we have shown variation in clinical practice related to surgical care of breast cancer," writes Dr. Geoff Porter, Ramia Chair in Surgical Oncology and Professor of Surgery, Dalhousie University. "This is an important first step in understanding how care can be improved."

One year after surgery for lumpectomy, 8854 women (23%) underwent surgical re-excision to remove cancerous tissue. These rates, and the type of additional surgery (mastectomy or breast-conserving surgery), also varied substantially depending on province or territory.

"Unfortunately, there is no pan-Canadian standard for acceptable margins following breast-conserving surgery," write the authors.

Rates of prophylactic mastectomy for the second breast following initial mastectomy are about half that in the United States; 6% of women in Canada underwent the procedure over the time period of the study.

The study also looked at day surgery and reconstructive breast surgery rates.

The Canadian findings are consistent with population-based studies in the United States and the United Kingdom.

"Further research is needed to better understand these variations and their impact on patient outcomes, as well as to inform potential quality initiatives," the authors conclude.

The study was conducted by the Canadian Institute for Health Information and the Canadian Partnership Against Cancer.

CMAJ Open, an online open-access journal that publishes high-quality medical and health research, comes from the same family as the Canadian Medical Association Journal (CMAJ).