How Medcan's breast screening approach goes beyond mammography
Why dense breast tissue matters, and what Medcan recommends
For more than 40 years, mammography has been the cornerstone of breast cancer screening, helping improve outcomes through early detection. Yet for many women, an important piece of information isn’t often addressed: Breast density.
If you've ever been told you have ‘heterogeneously dense’ or ‘extremely dense’ breasts, you're among the 40-50% of Canadian women in the same category. Having dense breasts is common. Yet many women don't realize that dense breast tissue can both mask cancers on a mammogram and increase your risk of developing breast cancer altogether.
Knowing this may leave many women asking: Is a mammogram enough? To address this gap, Medcan has implemented a standardized breast screening approach that goes beyond mammography for women with dense breasts. While mammography remains the cornerstone of screening, Medcan now automatically incorporates supplemental breast ultrasound for clients with dense breast tissue.
- Nearly half of Canadian women are classified as having dense breasts.
- Dense breast tissue can mask cancers on a mammogram and increase your risk of developing breast cancer.
- Nearly 4 in 10 cancers may be missed on mammography alone.
- Medcan offers mammography plus ultrasound for women with dense breasts.
- Medcan recommends annual mammography for women with dense breasts and every 1-2 years for women with breast density A or B.
Why breast density changes the screening conversation
Breasts are made up of two types of tissue: fatty tissue, which is made of fat cells, and fibroglandular, which is composed of milk ducts, milk-producing glands (lobules), and connective tissue.
Breast density refers to the amount of fibroglandular tissue compared to fatty tissue in breasts. The greater the amount of fibroglandular (connective) tissue the denser the breast.
Density is categorized by radiologists using four classifications, ranging from A – almost entirely fatty – to D – extremely dense. Women with Breast Density C – heterogeneously dense – or D have the highest amount of dense tissue.
Breast density: determined by how much firm tissue versus fat is in the breasts. The more firm tissue a person has, the denser their breasts are.
When you look at a mammogram, dense breast tissue and many breast abnormalities can appear similar. Fatty tissue appears dark on a mammogram and makes it easier for radiologists to spot abnormalities. Fibroglandular (dense) tissue, appears white on a mammogram, as do many breast cancers, which can make abnormalities more difficult to detect.
In practical terms, that means a standard mammogram may be more likely to miss cancer in a dense breast than in a less dense one.
Breast density is also recognized as its own risk factor for breast cancer, separate from family history or genetics. People with Breast Density C or D sit in a higher risk category than those with less dense breasts.
While the exact scientific reason isn't fully understood, experts believe this higher risk may be related to the greater amount of glandular and connective tissue in dense breasts, where the breast tissue environment itself may be more biologically active.
Additionally, according to Medcan Clinical Director of Women’s Health, Dr. Jennifer Zelovitsky, “New research suggests that dense breast tissue is stiffer than fatty breast tissue. This may play a role in the development of breast cancer.”
New research suggests that dense breast tissue is stiffer than fatty breast tissue. This may play a role in the development of breast cancer.- Dr. Jennifer Zelovitsky, Medcan's Clinical Director of Women's Health
The traditional screening approach
Current breast imaging guidance supports radiologists to consider supplemental screening for people with these higher density categories. MRI is preferred when available, followed by contrast enhanced mammography (which uses dyes to highlight areas with increased blood flow) or ultrasound as appropriate tools.
Since mammographic sensitivity is reduced in dense breast tissue, bilateral breast ultrasound is provided as a supplemental screening tool for clients with Breast Density C and D to improve lesion detection and characterization, thereby enhancing the overall effectiveness of breast cancer screening.
This means that in some cases, additional imaging, such as ultrasound, may be recommended based on breast density, individual risk factors, symptoms, or a radiologist's assessment. Yet access to, and use of, supplemental screening varies across healthcare providers, imaging centers, and jurisdictions.
This inconsistency matters when dense breast tissue can mask cancers on a mammogram. Without additional imaging when appropriate, some cancers may be detected later than they otherwise could be.
According to a large systematic review, mammography alone detects about 74% of cancers, while adding ultrasound increases detection to approximately 96%. Additionally, in women with extremely dense breasts, mammographic sensitivity can fall to approximately 62% or lower, meaning nearly 4 in 10 cancers may be missed on mammography alone.
How Medcan’s breast cancer screening protocol differs
To reduce variability, support clearer decisions, and early awareness, Medcan has introduced a new standardized approach for clients with Breast Density C or D identified on mammography. Our goal is to keep mammography as the foundation of breast screening, while adding targeted supplemental imaging for clients who meet the criteria.
For clients with Breast Density C and D tissue, Medcan now automatically includes a bilateral breast ultrasound as part of the routine breast screening pathway. The ultrasound is provided as supplemental screening to support improved assessment in extremely dense tissue, where mammography alone may be limited.
In some situations where ultrasound may not be recommended, the Medcan protocol is for the radiologist to document the rationale, which may include the absence of additional risk factors, recent supplemental imaging, stable imaging over time, a recommendation for an alternate screening modality, or limited expected benefit based on the clinical scenario.
Our approach recognizes that while mammography remains the gold standard of breast screening, women with dense breasts can benefit from additional imaging. By automatically incorporating supplemental ultrasound for clients with Breast Density C and D, Medcan aims to provide a more comprehensive view of breast health and support proactive, informed care.
Breast cancer screening isn't one-size-fits-all. Understanding your personal risk factors, including breast density, can help ensure you're receiving the most appropriate screening for your needs.
Additional preventative tests for women with dense breasts or other risk factors
Most women at average risk of breast cancer should start regular mammogram screening at age 40 to 50. In Canada, the age depends on provincial screening programs and personal preferences.
At Medcan, we recommend that breast cancer screening begin at age 40 for all women at average risk. Ontario’s breast screening guidance changed a few years ago, with the Ontario Breast Screening Program lowering the starting age from 50 to 40 effective October 8, 2024. Medcan aligned with this industry shift at the time, consistent with our long-standing focus on earlier detection.
At Medcan, we recommend screening begins at 40 for all women. Screening is also recommended every 1 to 2 years for most women. “At Medcan, we recommend annual mammography for women with dense breasts and every 1-2 years for women with Breast density A or B,” explains Dr. Zelovitsky.
At Medcan, we recommend annual mammography for women with dense breasts and every 1-2 years for women with Breast density A or B.- Dr. Jennifer Zelovitsky, Medcan's Clinical Director of Women's Health
However, women with higher-than-average risk, which may include dense breasts in addition a strong family history, certain genetic mutations, previous chest radiation, or other significant risk factors, may need to start earlier or engage in more frequent screenings.
For woman at a high risk who have concerns and want to be proactive, genetic tests are also available.
Inherited gene changes can influence breast cancer risk, and they are not limited to the well-known BRCA1 and BRCA2 genes. Medcan’s Enhanced Genetic Screening panel includes 12 known breast cancer-related genes, some of which may be found in people without a family history of breast cancer. Additionally, the test screens for your inherited risk for 45 health conditions including cancer, heart disease, and respiratory disease by analyzing more than 160 genes through a simple blood draw.
If someone is at high risk, after testing positive for certain breast cancer gene mutations, more intensive follow-ups may be recommended. That may include a clinical breast exam every six to 12 months starting as early as 25, along with MRI beginning in addition to mammography as early as 30. Breast MRI is typically not part of standard screening, which is why genetic testing can be a helpful tool in developing more personalized management recommendations.
Turning information into a proactive breast screening plan
Translating all of this into action starts with understanding your personal risk profile. That includes your breast density category, family history, any known gene mutations, and your age. Each of these factors influences which screening tools are most appropriate and how often they should be used.
If your mammogram report notes Breast Density C or D, you can expect Medcan to automatically include a bilateral breast ultrasound as part of your routine screening, unless there is a documented reason not to proceed, or you choose to decline. If it is not recommended, your radiologist will document why, whether that is due to recent supplemental imaging, stable findings, an alternate modality being preferred or limited expected benefit.
If you are unsure about your inherited risk, you may want to explore Medcan’s Enhance Genetic Screening to test for additional breast cancer genes, especially if you have a personal or family history of breast or related cancers. For those who test positive for certain mutations, a more intensive screening protocol may be recommended.
Take action
Our breast cancer screening protocol adds a breast ultrasound to mammography for women with dense breast tissue and is provided as part of Medcan’s Annual Health Assessment, an evidence-based, physician-led analysis that includes up to 15 screening stations and tests for 100+ biomarkers. The assessment leverages the latest in technology and clinical innovation to provide a comprehensive picture of your health with same-day results, insights, and personalized recommendations. Identify risk areas and maximize the opportunity for early detection of significant health concerns, such as cancer, heart disease, and diabetes.
Additionally, as part of the assessment, you can add a Enhanced Genetic Screening test to your day. It can also be done as stand-alone test to gain more insights into your genetic risk for breast cancer along with other conditions.
