STUDY SHOWS AN INCREASE IN BREAST CANCER SURVIVAL RATES

Early detection of breast cancer saves lives. This is a common claim made by breast cancer screening programs but is it true?

In England, a recent study followed 512,447 women registered with early invasive breast cancer (involving only breast and possibly axillary nodes) from January 1993 to December 2020. In July 2023, the results from this study were published in The BMJ.

The objective of the study was to estimate breast cancer mortality risks for groups of patients with a recent breast cancer diagnosis. It concluded that the prognosis for women with early invasive breast cancer has improved substantially since the 1990s. The five-year breast cancer mortality risk was 14.4% for women with a breast cancer diagnosis made during 1993-99 and 4.9% for women with a diagnosis made during 2010-15.

WHY HAVE MORTALITY RATES DECREASED?

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, the chances are better you will survive it. Early detection of breast cancer may mean less treatment, more treatment options, and less time spent recovering.

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. When it’s 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.

WHY IS REGULAR MAMMOGRAPHY SCREENING IMPORTANT?

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 several pictures. Then the process will be repeated for the other breast. It may be a bit uncomfortable, but it’s very quick, between 10-15 minutes in total.

All Mayfair Diagnostics’ mammography clinics use technology that provides 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 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 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 many 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 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 cancer 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. Available research puts the risk of overdiagnosis at 10%, compared to research that shows not participating in screening mammography leads to a 60% higher chance of dying from breast cancer.

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.
• Genetic predisposition (e.g., 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 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 14 locations which offer mammography exams and, except for Coventry Hills, all of them feature the latest technology that makes the experience more comfortable. This includes the option for patient-assisted compression – a remote control that allows the patient to adjust the level of breast compression during the exam, under the supervision of the technologist. Visit our breast imaging page for more information.

REFERENCES

Alberta Health Services Breast Cancer Screening Programs (2021) “Breast Cancer Screening.” www.screeningforlife.ca. Accessed December 18, 2023.

Canadian Association of Radiologists (2016) “CAR Practice Guidelines and Technical Standards for Breast Imaging and Intervention.” www.car.ca. Accessed December 18, 2023.

Canadian Cancer Society (2023) “Breast cancer statistics.” www.cancer.ca. Accessed December 18, 2023.

Mayo Clinic Staff (2022) “Breast cancer types: What your type means.” www.mayoclinic.org. Accessed December 18, 2023.

Monticciolo, Dr. et al. (2018) “Current Issues in the Overdiagnosis and Overtreatment of Breast Cancer.” American Journal of Roentgenology. February 2018, 210 (2). Accessed December 18, 2023.

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 December 18, 2023.

Taylor, C., et al. (2023) “Breast cancer mortality in 500 000 women with early invasive breast cancer diagnosed in England, 1993-2015: population based observational cohort study.” The BMJ. 2023; 381: e074684. Accessed December 18, 2023.