Wide variation in mastectomy rates across Canada

OTTAWA — In 2012, roughly 22,700 women will be diagnosed with invasive breast cancer — and many of them will require surgery as part of their treatment. A new report released today by the Canadian Institute for Health Information (CIHI) and the Canadian Partnership Against Cancer (the Partnership) shows that substantial variations exist in the use of surgical breast cancer treatments across the country. These insights, along with information about the factors that help explain patterns and variations, can be used to inform health system improvements.

The study, Breast Cancer Surgery in Canada, 2007-2008 to 2009-2010, examines surgical care for women with invasive breast cancer and those with the non-invasive form of the disease, ductal carcinoma in situ (DCIS). Based on three years’ worth of data (2007-2008 to 2009-2010), the report follows the surgical treatment of approximately 22,000 women for one year starting from the date of their initial surgery.

“By providing insights into trends and patterns that will help to improve treatments, this report has the potential to strengthen outcomes and quality of life for women with breast cancer — the most commonly diagnosed cancer among Canadian women,” says Anne McFarlane, CIHI’s Vice President, Western Canada and Developmental Initiatives.

Mastectomy and breast-conserving surgery (BCS, commonly known as a lumpectomy) are two types of surgery used to treat invasive cancer and DCIS. For women diagnosed with smaller tumours, evidence shows that BCS followed by radiation treatment provides a survival rate comparable to mastectomy. Both treatment options present little risk of complications — 7-day and 30-day complication rates were 2% or less for BCS and 6% or less for mastectomy for both invasive breast cancer and DCIS (rates pertain to the period 2007-2008 to 2009-2010).

Across Canada, 39% of women with unilateral invasive breast cancer — cancer in one breast — had a mastectomy within a year of their initial surgery. (In 32% of cases, women with this type of cancer undergo mastectomy as their first surgery. Among those who start with BCS, roughly 1 in 10 [11%] require a mastectomy within a year.) Crude mastectomy rates varied greatly across Canada, ranging from 26% in Quebec to 69% in Newfoundland and Labrador.

Rates of re-operation following BCS vary across provinces

Some women who initially undergo BCS require subsequent operations to remove, or excise, additional tissue (re-excision). Re-excision can range from a widening of the original BCS site to a full mastectomy. “Until now, there’s been little information available about re-excision rates from a pan-Canadian perspective,” says Anne McFarlane. “Our joint report looks at national surgical patterns and shows that re-excision is relatively common for Canadian women following breast conserving surgery.” During the time frame of the study (2007-2008 to 2009-2010), 23% of women with invasive breast cancer and 36% of women with non-invasive breast cancer (DCIS) required at least one additional operation following the initial BCS. Of the 23% with invasive breast cancer, 11% underwent mastectomies, while 12% underwent further BCS.

Across the provinces, re-excision rates (within one year of the initial BCS procedure) varied significantly. Newfoundland and Labrador demonstrated the highest re-excision rate following BCS, at 56%. Manitoba’s and Quebec’s re-excision rates following BCS were lower, at 17%.

Age and travel time affect mastectomy rates

Among women with invasive breast cancer, the CIHI-Partnership study identified a U-shaped relationship between age and mastectomy rates. Rates were relatively high (44%) for women age 18 to 49. Rates then fell to 35% for those age 50 to 69 and rose again to 45% for women age 70 and older. While the choice between mastectomy and BCS is heavily influenced by the extent of the disease upon diagnosis, factors such as perceptions of risk, body image and attitudes toward radiation therapy and breast reconstruction play a role in determining treatment choices.

Women who choose BCS as their surgical option typically undergo post-surgical radiation therapy — therapy provided only at certain cancer centres and often requiring daily trips. The report shows an increase in mastectomy rates corresponding to travel time greater than 40 minutes (between a woman’s home and the cancer centre offering radiation treatment). Mastectomy rates exceeded 50% for women who must travel 1.5 hours or longer (each way) to reach a centre offering radiation treatment.

“This report confirms what we suspected — that there are variations in the use of surgery as a treatment option for breast cancer based on a range of factors,” says Dr. Heather Bryant, Vice-President, Cancer Programs, Clinical and Population Health at the Canadian Partnership Against Cancer. “Armed with information like this, health system planners and clinicians are in an ideal situation to identify strengths and opportunities within existing practice, which can collectively help to optimize breast cancer care and the experience of women who receive surgery as part of their treatment.”

About the Canadian Partnership Against Cancer

The Canadian Partnership Against Cancer is an organization funded by the federal government to accelerate action on cancer control for all Canadians. We bring together cancer experts, government representatives, the Canadian Cancer Society and cancer patients, survivors and their families through the Canadian Cancer Action Network to implement the first pan-Canadian cancer control strategy. We aim to be a driving force to achieve a focused approach that will help prevent cancer, enhance the quality of life of those affected by cancer, lessen the likelihood of dying from cancer and increase the efficiency of cancer control in Canada.

About the Canadian Institute for Health Information

The Canadian Institute for Health Information (CIHI) collects and analyzes information on health and health-care in Canada and makes it publicly available. Canada’s federal, provincial and territorial governments created CIHI as a not-for-profit, independent organization dedicated to forging a common approach to Canadian health information. CIHI’s goal: to provide timely, accurate and comparable information. CIHI’s data and reports inform health policies, support the effective delivery of health services and raise awareness among Canadians of the factors that contribute to good health.