Live Well: About Dense Breasts

Even with regular mammograms, breast cancer can sometimes go undetected—one reason for this is breast density. Dense breasts not only make it harder to spot cancer on a mammogram, but they also increase your overall risk of developing breast cancer.

What Is Breast Density?

Breast density refers to the proportion of different types of tissue in your breasts. All breasts contain glands, fibrous tissue, and fatty tissue, but the ratio varies from person to person. Breasts are considered dense when they have more glands and fibrous tissue than fat.

You can’t determine breast density by look or feel. Most people learn about their breast density after a mammogram. In Ontario, Cancer Care Ontario includes this information in the follow-up letter sent after your screening. You can also call the Ontario Breast Screening Program (OBSP) at 1-800-668-9304 to ask about your breast density.

How Common Is Breast Density?

Breast density is common and varies with age:

• About 56% of people in their 40s have dense breasts.
• By age 60, that number drops to 27%.

Breast Density Categories

Breast density is classified into four categories:

• Category A & B: Mostly fatty tissue; lower risk.
• Category C & D: Heterogeneously dense or extremely dense; higher risk and harder to detect abnormalities via mammogram.

In Ontario, people with Category D density are recommended to have annual mammograms instead of every two years. Additional screening methods like ultrasound or MRI may also be beneficial.

What You Can Do

If you have dense breasts, there are proactive steps you can take:

• Perform regular self-examinations.
• Discuss additional screening options with your healthcare provider.
• Consider lifestyle changes to reduce cancer risk, such as:
  • Eating a balanced diet
  • Exercising regularly
  • Limiting alcohol intake
  • Reviewing hormone use

Talk to your primary care provider to determine what’s best for your individual health needs.