Do you know your breast density?
Breast density is a measure of glandular to fatty tissue in the breast. It’s assessed on mammogram - you can’t tell breast density by breast size, look or feel
There are 4 categories of breast density
A - <25% dense, ~10% of women
B – 25-50% dense, ~ 40% of women
C – 50-75% dense, ~ 40% of women
D - >75% dense, ~ 10% of women
Category C and D are “dense breasts”
How do I know my breast density?
As of July 2023 in Ontario, breast density will be noted on your mammogram report or screening letter.
If you don’t see it on your report, ask your healthcare provider about your breast density category (A,B,C,D).
What causes high breast density?
Breast density is largely determined by age, hormone status and genetics.
Breasts usually become less dense with age and menopause. Estimated 56% of women in their 40’s have dense breasts, down to 27% in their 60’s.
Estrogen from the birth control pill or menopause hormone therapy can increase breast density.
Why is it important to know my breast density?
1. Breast cancer risk
High breast density is a variation of normal, however the higher the breast density, the higher risk of breast cancer. Women with breast density >75% have estimated 4-6x the risk of developing breast cancer compared to women with breast density <25%. In fact, having dense breasts is a more prevalent risk factor than having a family history of breast cancer.
Risk is twofold:
Dense breasts are believed to be at higher risk for cancer growth AND
Density makes it more difficult to visualize tumors. Mammograms can detect cancer in 98% of fatty breast tissue and only 40% in dense breast tissue
2. New breast screening recommendations
If you have dense breasts, annual mammogram with ultrasound or MRI is the highest standard of care. Each province has its own screening guidelines. In December 2023 Ontario announced a recommendation for additional screening (mammogram with MRI or ultrasound) for those with Category D breast density. It it will take time for the recommendations to be implemented and in the meantime you may need to advocate for this.
3. Hormone therapy consideration
Estrogen therapy increases breast density. While high breast density isn’t a contraindication to hormone therapy, it’s a factor when weighing benefit vs risk.
2023 was a big year in Ontario for updating breast recommendations. Here’s what to know to stay up to date:
-When you have your mammogram, ask your physician for a copy of the report or access it directly by signing up for pockethealth.com. Your breast density (A, B, C, D) will be noted on the report.
-If you’re category D, advocate for additional screening (mammogram with MRI or ultrasound). To be prepared for this conversation with your doctor, refer to a script found here at densebreastscanada.ca
For more information www.densebreastscanada.ca, accessed Feb 2024