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Breast Screening Technology

The aim of breast cancer screeningScreening:
the search for diseases such as breast cancer in people without symptoms. Mammography is an important tool for breast cancer screening and earlier detection.
is to reduce mortality ratesMortality (rate):
The number of people that die from a disease in a population over a period of time.
by detecting breast cancer early. When breast cancer is detected at an earlier stageStage:
a way of classifying breast cancer that describes how far a cancer has spread. It identifies whether breast cancer is at an early, locally advanced or metastatic stage. The stage of breast cancer can sometimes be represented as a number (e.g. between 0 and 4).
, most people have more treatment options, less invasive treatment and a better chance of surviving the disease. As a result of advancements in breast cancer screening, diagnosis and treatment, the breast cancer mortality rates has fallen by 43% since the 1980s, which means more women are living longer, healthier lives.


There are different ways that people can be screened for breast cancer. Mammography Mammogram (also called mammography):
A low-dose X-ray of the breast. It is used to take images of the breasts and is an important screening tool for the earlier detection of breast cancer.
is the most commonly used method of breast cancer screening in many places. It has been widely tested and proven to help reduce deaths from breast cancer by 25-35% in women who start screening by mammography from the age of 40.

There are two main types of mammography technology – screen-film mammography and digital mammographyDigital mammography:
a low-dose X-ray similar to screen-film mammography, equipped with a digital receptor and a computer instead of film.
. Both types of mammograms work by taking images of your breast tissue using low dose x-rays, which are then read by a radiologistRadiologist:
A doctor who specializes in reading tests such as ultrasounds and X-rays. A radiologist may also perform core biopsies and use imaging techniques to guide cancer treatment.
who looks for any abnormalities that may be breast cancer.

Digital mammography has largely replaced screen-film mammography in most parts of Canada. This is because it is better at detecting breast cancer in women in their 40s, women 50+ who have not gone through menopauseMenopause:
a natural part of a woman's aging process, when the ovaries start to make less estrogen and progesterone and the menstrual periods stop. This change typically occurs between the late 40s and mid-to-late 50s.
, and women with clinically diagnosed dense breastsDense breasts (breast density):
Dense breasts have less fat and more glandular and connective tissue. A woman’s breast density depends on her age and genetic factors. Breast density is a risk factor for breast cancer. Having “dense breasts” is a clinical diagnosis that can only be assessed by mammography.
. Wherever it is available, Canadian Breast Cancer Foundation encourages women to be screened with digital mammography.

For women who are at average risk of breast cancer (approximately 80% of women in Canada), mammography is the most effective and appropriate screening method. In the section below, we introduce other technologies that are used alongside digital mammography to screen women at higher risk of breast cancer – as well as newer screening technologies that are being developed.


Breast ultrasoundUltrasound:
an imaging technique that uses sound waves to take a picture of structures in the body, such as the breast.
can be useful as an additional screening technology in women at higher risk of developing breast cancer or women with clinically diagnosed dense breasts. Where breast MRIMagnetic Resonance Imaging (MRI):
an imaging technique that uses powerful magnetic fields and radio waves to create detailed, 3-dimensional images of the organs and tissues in the body, such as the breast.
is not available, ultrasound has a role to play in screening women at intermediate or high risk of breast cancer. Breast ultrasound is often used in combination with mammography and MRI to provide additional screening information and is also a method used for breast cancer diagnosis.

Ultrasound uses high frequency sound waves to create an image of structures in the body, such as the breast. It does not use ionizing radiation (e.g. X-ray). Ultrasound is able to tell the difference between fluid-filled cystsCyst:
A fluid-filled sac that is usually benign (non-cancerous). The fluid may be removed for analysis.
and solid tumoursTumour:
an abnormal mass of tissue that occurs when cells divide more than they should or do not die when they should. Tumours may be benign (not cancer) or malignant (cancer). A tumour is also called a neoplasm.
, but cannot always distinguish between a cancerous (malignant) and non-cancerous (benign) tumour. A biopsyBiopsy:
A procedure in which tissue samples are removed from the body for examination under a microscope to determine if cancer or other abnormal cells are present.
is usually required to determine if a tumour is cancerous.

Magnetic Resonance Imaging (MRI)

Where available, Magnetic Resonance Imaging (MRI) of the breast is combined with mammography to screen for breast cancer in women who are at high risk. An MRI is used in addition to a mammogram because younger, pre-menopausal women have greater breast density, which can make it more difficult to see abnormalities with mammogram alone. Breast cancers in women who are at high risk tend to grow faster, and when available, the combination of MRI and mammogram is better at detecting breast cancer in this population than either technology alone.

An MRI uses a powerful magnet and radio-frequency waves to create an image of structures in the body. It does not use ionizing radiation. As with an ultrasound, an MRI may not be able to tell the difference between a cancerous and non-cancerous tumour, and a biopsy may be required to confirm a diagnosis.

Emerging screening technologies

Molecular breast imaging is being tested for its ability to detect smaller, earlier breast cancers in high-risk women with clinically diagnosed dense breasts. It will not replace mammography, but may offer a more effective screening option for some. A clinical trialClinical trial:
One of the most common types of experimental studies in humans is the clinical trial. Clinical trials are designed to test new ways to prevent, detect, and treat specific diseases.
of this new technology is taking place in Canada, but the technology is not licensed for population-based breast cancer screening here.

Digital breast tomosynthesis (DBT) is a newer technology that is approved for use in Canada, but is not yet widely available. Like mammography, it uses X-rays to take pictures of the breast, but creates a 3-dimensional (3D) image rather than the 2-dimensional (flat) image produced by conventional digital mammography. 

DBT may be especially useful for screening women with dense breasts because the 3D image that is produced makes it easier to see breast cancers that may be hidden by dense breast tissue on conventional mammography. Evidence suggests that DBT may be able to detect smaller breast cancers and with more accuracy, decreasing the likelihood of being called back for more testing after a screening test. The procedure also requires less compression to get an image, making mammograms more comfortable for women. Research is ongoing to better understand how best to use this newer technology in population-based breast cancer screening.

Other technologies are being developed that may help to improve the earlier detection of breast cancer in the future, including breast computed tomography, and biomarker imaging. 

Thermography is not recommended for breast cancer screening

No credible scientific evidence has shown that thermographyThermography:
(Also called thermal imaging or infrared imaging) is a computerized imaging tool that measures heat distribution at the surface of the breast. While thermography may be appealing to some women because it is a pain-free exam, scientific research has shown that thermography is not reliable for detecting breast cancer.
is an effective tool for detecting breast cancer, helps to reduce breast cancer mortality, or can indicate a person’s risk of developing breast cancer. Thermography is an unlicensed, unregulated service with no proven clinical value for the detection of breast cancer.

While thermography has been available for many years, it is not recommended by any leading cancer organization or medical authority as a substitute for screening mammograms.

Research on thermography

Claims that thermography is useful in diagnosing breast cancer have not been proven. In fact, research studies since the 1970s have consistently concluded that thermography is not a reliable breast cancer screening tool because it can miss a significant number of breast cancers and has a high proportion of false positive results (meaning that it shows signs of breast cancer when none are there, requiring follow-up by mammogram, ultrasound or other diagnostic tools to rule cancer out).

Given its limitations, thermography may be detrimental to the health of women who rely on its results to identify pre-cancerous conditions or detect breast cancer. Thermography is not licensed by Health Canada as a population-based breast screening tool nor is the practice regulated or accredited in Canada, or covered by provincial or territorial health insurance programs.

Health Canada Advisory on Thermography

On Nov 28, 2012, Health Canada advised that no thermography machines have been approved to screen for breast cancer in Canada. Health Canada will work with the provincial and territorial ministries of health to stop the use of thermography as a tool for breast cancer detection.

In contrast, mammography is licensed and regulated by Health Canada as a tool to screen and diagnose breast cancer and is covered by health insurance programs in Canada. Provincial and territorial screening programs offer the highest quality breast cancer screening and are accredited by the Canadian Association of Radiologists. Mammography is the most widely-tested breast cancer screening tool and is currently the most accurate diagnostic modality available for the earlier detection of breast cancer.



Breastcancer.org. Digital Tomosynthesis. Accessed March 16, 2014.

Canadian Breast Cancer Foundation. (2010). Earlier Detection and Diagnosis of Breast Cancer: A Report from It’s About Time! A Consensus Conference. Toronto, ON: Canadian Breast Cancer Foundation.

Canadian Breast Cancer Foundation. (2010).  Earlier Detection and Diagnosis of Breast Cancer. Recommendations and Scientific Review from It’s About Time! A Consensus Conference. Toronto, ON: Canadian Breast Cancer Foundation.

Canadian Cancer Society. Ultrasound. Accessed March 16, 2014.

Canadian Cancer Society. Magnetic Resonance Imaging (MRI). Accessed March 16, 2014.

Health Canada. It’s Your Health: Mammography.  Accessed June 23, 2014. 

Health Canada (2012). Thermography machines are not authorized to screen for breast cancer. Accessed November 28, 2012.

Health Imaging. NJEM: Screening mammography recommended for most women. Accessed June 23, 2014.

Helvie, M.A. (2010). Digital Mammography Imaging: Breast Tomosynthesis and Advanced Applications. Radiologic Clinics of North America, 48 (5), 917-929.

Pisano, E. et al. (2005) Diagnostic Performance of Digital versus Film Mammography for Breast-Cancer Screening.  New England Journal of Medicine, 353 (17), 1773-1783.

Society of Breast Imaging. Breast thermography. SBI position statement. Accessed June 23, 2014.

The Canadian Agency for Drugs and Technologies in Health (2012). Infrared Thermography for Population Screening and Diagnostic Testing for Breast Cancer. Issues in Emerging Health Technologies, Issue 118.

Warner, E. (2011). Breast Cancer Screening.  New England Journal of Medicine, 365 (11), 1025-1032.