Mammograms for Women in Their 40’s Deemed Redundant

New guidelines recommend that women aged 40 to 49 do not need routine breast cancer screening with mammography, since the relatively small mortality benefit is countered by an increased risk of over-diagnosis and unnecessary treatment.

The new breast cancer screening guideline published by the Canadian Task Force on Preventive Care (Ottawa), an independent body of 14 primary care and prevention centers, recommends no routine mammography screening for women aged 40-49, and extends the screening interval from every two years--which is current clinical practice--to every two to three years for women aged 50-74. The guidelines, aimed at physicians and policy-makers, provide recommendations for mammography, magnetic resonance imaging (MRI), breast self-exams, and clinical breast exams by clinicians.

According to the new guidelines, outcomes of breast cancer screening such as tumor detection and mortality must be put into context of the harms and costs of false-positive tests, overdiagnosis, and overtreatment. Among the key recommendations made is that no routine mammography for women in their 40’s should be performed, as the risk of cancer is low in this group, while the risk of false-positive results and overdiagnosis and overtreatment is higher. The committee also recommended routine screening with mammography every two to three years for women aged 50-69; routine screening with mammography every two to three years for women aged 70-74; and no screening of average-risk women using MRI. The guidelines were published in the November 8, 2011, issue of Canadian Medical Association Journal (CMAJ).

“As the Guideline on Breast Cancer Screening was last updated in 2001 and breast cancer screening has since become a subject for discussion amongst doctors and patients, the revitalized Canadian Task Force selected breast cancer screening as the topic for its first guideline,” said Marcello Tonelli, MD, chair of the Task Force and an associate professor at the University of Alberta (Edmonton, Canada). “We intend that this guideline, which reflects the latest scientific evidence in breast cancer screening, be used to guide physicians and their patients regarding the optimum use of mammograms and breast examination.”

“There was no evidence that screening with mammography reduces the risk of all-cause mortality,” added the authors. “Although screening might permit surgery for breast cancer at an earlier stage than diagnosis of clinically evident cancer (thus permitting the use of less invasive procedures for some women), available trial data suggest that the overall risk of mastectomy is significantly increased among recipients of screening compared with women who have not undergone screening.”

The debate over the need for screening mammography has raged since 2009, when the US Preventive Services Task Force (USPSTF; Rockville, MD, USA) made similar recommendations. The debate has shown no signs of petering out, with some studies showing that mammographic screening in women 40 to 49 offers a worthwhile mortality benefit, while others that have found only a trivial benefit. In 2010, the American College of Obstetricians and Gynecologists came out in support of mammographic screening beginning at age 40.

Related Links:
Canadian Task Force on Preventive Care
US Preventive Services Task Force