BREAST CANCER SCREENING AND THE EFFECTIVENESS OF MAMMOGRAMS
The survival rates for breast cancer have been increasing since the 1980s, thanks to earlier detection from regular mammogram screening and improvements in breast cancer treatments. According to the Canadian Cancer Society, breast cancer will affect one in eight women in Canada, but if you find it early, there are more ways to treat it and the chances are better you will survive it.
The best way to detect breast cancer early is by having regular screening mammograms before you develop symptoms of breast cancer like pain, lumps, or other changes to the breast. This is why educating women about early detection is often the main goal of breast awareness month and its associated fundraisers and campaigns.
Having a mammogram every year, or every two years (based on your risk factors), makes it easier for a radiologist to compare your images and see changes or areas of concern. If you wait until you have symptoms, the breast cancer might be bigger and harder to fight.
Mammography is a type of X-ray exam that takes an image of the inside of the breasts. During your exam, the machine will gently press down on the breasts to spread the breast tissue out and capture a more complete picture of each breast. The pressure lasts for a few seconds, while the machine quickly takes a number of pictures. Then the process will be repeated for the other breast. It may be a bit uncomfortable, but it’s very quick, only 10 or 15 minutes in total.
All Mayfair Diagnostics’ mammography clinics use technology that provides traditional 2D images of the breast, as well as 3D images (tomosynthesis) of the breast that can then be viewed in slices. This provides a greater level of detail and a clearer view of the breast tissue with a very small dose of radiation.
Once the pictures have been taken, one of our doctors will look over them very carefully to check for possible abnormalities or changes compared to previous images. This is the best way to detect breast cancer in its early, most treatable stage, because it provides a detailed look at the internal structure of breast tissue and can reveal changes that are too small to feel.
WHEN SHOULD I START HAVING A MAMMOGRAM?
All women should have a mammogram. Many people start having regular mammograms every year at about age 40, since Alberta Health Care covers one mammogram per year starting at that age. If you have pain or a concern about your breasts earlier than that, you can of course go see your doctor and arrange to have a mammogram. To get a mammogram, you will need to speak to your doctor about your family history, when to start screening, and how frequently you should be screened.
Mayfair Diagnostics recommends screening mammography every year from age 40 to 49, then every two years between age 50 and 75, if there are no risks factors that would necessitate a shorter interval. After age 75, screening frequency will depend on a number of factors, including your medical history.
Across Canada the recommended age to start screening and the recommended screening intervals differ by province. Most provincial and federal breast screening guidelines are based on an evaluation of whether the benefits of regular screening mammograms outweigh the potential harms. Mayfair’s recommendations for breast screening are aligned with the Canadian Society of Breast Imaging and the Canadian Association of Radiologists.
WHAT ARE THE RISKS OF REGULAR BREAST SCREENING?
When deciding between the benefit of early detection of breast cancer and the potential harms associated with breast screening there are two main harms that are often considered. The first is radiation exposure and the second is overdiagnosis.
Many women are concerned about the cumulative effects from radiation exposure during a mammogram. However, mammograms require a very small dose of radiation – the same amount of radiation as every person receives from the earth's natural background radiation over six months. Since the risk of harm from this amount of radiation exposure is low compared to the prognosis when breast cancer is detected early, many women decide the benefit outweighs the risk.
Overdiagnosis includes unnecessary treatment of cancer that would not have caused harm in a woman’s lifetime, as well as the physical and psychological consequences of false positives. Current research puts the risk of overdiagnosis at 10 percent, compared to research that shows not participating in screening mammography leads to a 60 percent higher chance of dying from breast cancer.
WHAT ARE THE BENEFITS OF SCREENING?
Early detection is the primary reason for screening. When breast cancer is detected through imaging and before it is clinically apparent (e.g. palpable lump), it’s more likely to be small and more easily treated. Small cancers detected early can be removed and breast conserving surgery can be performed. Additionally, small cancers often do not require chemotherapy or radiation therapy.
WHAT ARE THE RISK FACTORS FOR DEVELOPING BREAST CANCER?
Women with the following risk factors are considered high risk and may be encouraged to start screening earlier and more frequently.
- Personal history of breast or ovarian cancer.
- First-degree relative (parent, sibling, child) diagnosed with breast or ovarian cancer.
- BRCA1, BRCA2 positive.
- Three or more second-degree relatives with breast or ovarian cancer.
- Volpara D (extremely dense) breast density* score.
- Chest wall radiation at an age younger than 30.
- History of lobular carcinoma in situ or atypical hyperplasia on previous breast biopsy.
*Dense breast tissue refers to how it appears on the mammogram based on the mix of fatty and fibrous tissue. Women with very dense breasts may require a more personalized screening approach than what is recommended for the general population. This may include both mammography and ultrasound exams.
While the recommendations differ, the ultimate decision rests with women. Understanding the risks and benefits of regular mammogram screening and speaking with your doctor about your medical history is an important first step to decide what’s right for you.
Mayfair Diagnostics has 12 locations which offer mammography exams, including Mahogany Village, Market Mall, Mayfair Place, Cochrane, and Southcentre locations which have the new Pristina mammography system – which helps provide a more comfortable mammogram. Visit our breast imaging page for more information.
Canadian Association of Radiologists (2016) “CAR Practice Guidelines and Technical Standards for Breast Imaging and Intervention.” www.car.ca. Accessed May 17, 2021.
Canadian Society of Breast Imaging (2018) The Canadian Society of Breast Imaging response to the new CTFPHC Guidelines. www.csbi.ca. Accessed May 17, 2021.
Coldman, A., et al (2014) “Pan-Canadian Study of Mammography Screening and Mortality from Breast Cancer.” Journal of the National Cancer Institute. November 2014, 106 (11). Accessed May 17, 2021.
Monticciolo, Dr. et al. (2018) “Current Issues in the Overdiagnosis and Overtreatment of Breast Cancer.” American Journal of Roentgenology. February 2018, 210 (2). Accessed May 17, 2021.
Tabar, L., et al. (2018) “The incidence of fatal breast cancer measures the increased effectiveness of therapy in women participating in mammography screening.” Cancer. Accessed May 17, 2021.