Mammography screening: Weighing the pros and cons for women’s health

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Publication Date: 
Tue, 2012-07-17

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The Canadian Task Force on Preventive Health Care released its guideline on screening for breast cancer for average-risk women (aged 40 to 79) in late 2011. The guideline updated screening recommendations made by the Task Force’s predecessor, the Canadian Task Force on the Periodic Health Examination, in 2001. The focus of the guideline is on mammography screening, but the guideline authors also recommended against clinical breast examination (by physicians) and breast self-examination by patients. The Task Force issues guidelines for primary care (family) doctors on a range of preventive care issues. In this article, journalist Ann Silversides wades through the recent controversies about the guideline, explaining the issues and summarizing the evidence and current thinking about mammography screening. See also: Breast self-examination: What it means and why the thinking about it has changed.

By Ann Silversides


Photo: With permission from St David's HealthCare (Flickr).

The current debate about the value of mammography erupted last fall when the Canadian Task Force on Preventive Health Care released its recommendations for breast cancer screening for “average-risk women 40 to 74.”

The public wrangling has left women confused about what to do about mammography screening.

On November 22, 2011, the day after the recommendations were made public, a Toronto Star news story opened with the statement: “The mammogram wars have come to Canada.”

The “wars” refers to the firestorm of controversy in the United States when a similar U.S. task force had, in 2009, recommended against routine screening for women aged 40 to 49 years.

In the United States, this represented a radical change of policy. Previously, screening mammography had been recommended every one to two years for all women over 40.

But the Canadian position was not new. The Canadian Task Force on Preventive Health Care was repeating a recommendation—first made in 1994 and endorsed again in 2001—against routine screening for women 40 to 49 years old. It did, however, recommend routine screening for average risk women 50 to 69 years old every two to three years.

Organized breast cancer screening programs began in Canada in 1988 and are now in place in all provinces and territories except Nunavut. Most programs involve screening women 50 to 69 years old every two years, but British Columbia and Alberta invite women 40 and older into screening, although Alberta requires a doctor’s referral letter.

Even though the Task Force recommendation about who should be eligible for routine screening did not change, it provoked controversy and often hard-to-follow arguments. Technical debates based on statistics pit those who argue that formal screening programs should be expanded to younger women (on the basis that mammography benefits have been underestimated) against those who maintain that benefits have been exaggerated and harms downplayed. [See the series on these issues  and the position of the Canadian Breast Cancer Foundation on the screening debate].

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