Women aged forty to forty-nine should not undergo routine mammography screening for breast cancer, according to new guidelines issued by the Canadian Task Force on Preventive Health Care, which were published in CMAJ (Canadian Medical Association Journal). The Task Force also recommends that the screening interval be extended to every two to three years for females aged 50 to 74, from every two years.
Women should not carry out clinical breast exams and breast self-examinations if they have no symptoms pointing to breast cancer, the guidelines also recommend.
The new recommendations are directed at doctors and policy-makers, and provide guidance on mammography, MRI scans, clinical breast exams by doctors, and breast self-exams. They specifically focus on females in three age groups - 40 to 49, 50 to 59 and 70 to 74 years - and who neither have a history of breast cancer nor a family history with a close relative with the disease. A close relative means mother, sister or daughter.
Dr. Marcello Tonelli, Chair of the Task Force on Preventive Health Care and Associate Professor at the University of Alberta, Department of Medicine, in Edmonton, Alberta, said:
"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.
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."
The guideline says that a better balance is required between the harms and costs of overdiagnosis, overtreatment, and false positives and the outcomes of breast cancer screening with regard to tumor detection and mortality. Several recent studies have shown that routine breast cancer screening during middle age do not impact on mortality rates enough to outweigh the negative consequences of them.
Screenings that come up with a false-positive result can seriously impact on the patient's and her family's well-being, causing disruption and extra costs; they also use up resources of the health care system.
Dr. Tonelli said:
"Providing Canadians with guidelines that reflect the most current scientific evidence is our priority. We encourage every woman to discuss the risks and benefits of screening with their doctor before deciding on the best approach for them."
Below are the main recommendations:
- As the risk of cancer is very low for women aged 40-49, and the risks of overdiagnosis, overtreatment and false-positives are relatively high, there should be no routine mammography for this age group
- Women aged 50 to 69 years - routine screening should occur every two to three years
- Women aged 70 to 74 years - routine screening should occur every two to three years
- Average risk women should have no MRI screening
- There should be no routine clinical breast exams by doctors
- There should be no breast self-exams to screen for breast cancer
"There was no evidence that screening with mammography reduces the risk of all-cause mortality. 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 Canadian Task Force on Preventive Health Care consists of 14 primary care and prevention experts - it is an independent body. It was established by the Public Health Agency of Canada to "develop clinical practice guidelines that support primary care providers in delivering preventive health care".
In a Commentary piece in the same journal, Dr. Peter Gøtzsche, Nordic Cochrane Centre, Copenhagen, Denmark, remarks:
"These guidelines are more balanced and more in accordance with the evidence than any previous recommendations."
Gøtzsche explains that there is no evidence supporting the use of routine mammography screening, he says it is ineffective at best, and also harmful because the "diagnosis of cancers that would otherwise be undetected lead to life-shortening treatments and mastectomies".
Dr. Gøtzsche wrote:
"The main effect of screening is to produce patients with breast cancer from among healthy women who would have remained free of breast disease for the rest of their lives had they not undergone screening.
(conclusion) The best method we have to reduce the risk of breast cancer is to stop the screening program," he concludes. "This could reduce the risk by one-third in the screened age group, as the level of overdiagnosis in countries with organized screening programs is about 50%."
Written by Christian Nordqvist