Breast cancer guidelines

The recent screening guidelines for breast cancer1 by the Canadian Taskforce on Preventive Health Care (CTFPHC) have clarified the state of the science behind screening; however, many women and clinicians have expressed concerns. The new guidelines are nuanced and further discussion from the perspective of population-based screening is deserved.

The publication1 stated that the previous guidelines advised women aged 50–69 to have mammograms annually. In fact, CTFPHC previously recommended screening every one to two years. Average-risk women aged 50–69 do not routinely receive annual mammography in Canada. The new guidelines are similar to current practice in Canada. About 70% of women aged 50–69 have had mammography within a 30-month time period.2 Further, about 25% of women aged 40–49 have had annual mammography.

The new guidelines provide a “weak” level recommendation regarding routine screening with mammography for average-risk women aged 40–49 and aged 50–74.1 A weak recommendation implies some degree of choice based on individual circumstances. Clinicians must assist women in making informed choices consistent with the woman’s understanding of harms, benefits and personal values and preferences. In consideration of informed choice, the Canadian Breast Cancer Screening Initiative (CBCSI), which includes representation from all providers of population-based breast cancer screening in Canada, has produced a decision aid (www.publichealth.gc.ca/decisionaids). An online continuing medical education course related to breast cancer screening is also in development.

In Canada, the age-standardized mortality rate for breast cancer has fallen by more than 35% since 1986.3 The most significant drop occurred after 1996, which was six to eight years after the introduction of population-based screening programs in Canada and improved quality of mammography. The decline in mortality is attributable to both the uptake in screening and the use of more effective adjuvant therapies.4 The age-standardized incidence rate for breast cancer in Canada has remained relatively unchanged for twenty years.

The new guidelines look at the harms and benefits of screening mammography, as well as the values and preferences of the patient. Organized, high-quality, population-based breast cancer screening programs are an important public health initiative. Screening programs with comprehensive quality assurance and evaluation of program performance have shown to be more effective than screening that is not organized.5^,6 Early detection, in combination with appropriate treatment significantly lowers breast cancer mortality and improves the quality of life of patients with breast cancer.