WORLD DENSE BREAST DAY | Last Wednesday in September

(Last Updated On: March 29, 2023)

WORLD DENSE BREAST DAY | Last Wednesday in September

We highlight World Dense Breast Day on the last Wednesday in September to raise awareness about the importance of breast screening, breast density, and other screening tests women should consider after their mammogram.


Dense breasts can both hide cancers on a mammogram and also increase a woman’s risk of developing breast cancer. Because both dense tissue and tumors show up as “white” on a mammogram, cancers can be hidden in dense breast tissue. It’s like trying to find a snowball in a blizzard. Not only do dense breasts hide cancer on a mammogram, they also increase the risk of developing breast cancer. Today, on World Dense Breast Day, we all can raise awareness and share medically sourced educational resources on dense breasts.

To view images of mammograms with dense breast tissue, visit

Breasts are made of fat and glands (that make milk) held together by fibrous tissue. Each woman has a unique mix of fatty and dense (glands and fibrous) tissue in her breasts. Furthermore, the more glands and fibrous tissue that a woman has, the “denser” her breast tissue. Almost half of the women over the age of 40 have dense breasts. However, the denser the breast tissue, the greater the chance that a cancer will be missed. Unfortunately, a woman’s risk for breast cancer increases with the level of density in her breast.

Common Questions

What do I need to know about mammograms and dense breasts? An ultrasound or magnetic resonance imaging (MRI) may find cancers not seen on a mammogram in a woman who has dense breasts. Unfortunately, information about a woman’s breast density and other screening options are not always provided after a mammogram. Women should always talk to their health care provider about any additional tests available to them.

How do I find out if I have dense breasts? It is not possible to tell how dense the breasts are from the way they look or feel. A mammogram is the best way for women to learn their breast density. The radiologist who reviews the mammogram will rate breast density into one of four categories.

What are the categories of breast density?

  • (A) Fatty breasts are when most of the breast is made of fat tissue. About 10% of women have fatty breasts.
  • (B) Scattered fibroglandular density is when the areas of fatty and fibrous tissue are scattered throughout the breast. About 40% of women have scattered fibroglandular density.
  • (C) Heterogeneously dense means large portions of the breast are made of dense tissue. About 40% of women have heterogeneously dense breasts. Doctors consider breasts in category C dense.
  • (D) Extremely dense is when most of the breast is made of dense tissue. About 10% of women have extremely dense breasts. Doctors consider breasts in category D dense.

Breasts that are Categories C or D are considered “dense” breasts.

Lower Your Risk

How do I lower my risk of breast cancer? Studies show you can lower the risk of breast cancer by making simple lifestyle changes like:

  • Limiting your alcohol intake to one drink a day.
  • Eating healthier.
  • Exercising at least 4-5 hours a week.
  • Opting to breastfeed if you’re of childbearing age.
  • Limiting hormonal treatment if you are postmenopausal.


  • Learn more about dense breasts at
  • Schedule your mammogram and discuss your breast screening options with your doctor.
  • Participate and spread awareness by educating yourself and others about breast health.
  • Schedule a girls day and encourage conversations about breast health.
  • Donate to to help them provide educational information to everyone.
  • Follow, share and tag #WorldDenseBreastDay on social media and post stories, videos, and interactive images.


In 2022, National Day Calendar approved World Dense Breast Day to help spread the message on the importance of breast health. The day is brought to you by, which is the world’s leading resource on the topic and features educational resources for both women and health care providers. The day also encourages everyone to have conversations and share educational material on the topic of dense breasts.

Read the Press Release here: DBI-WDBD-release-final

Late September leads into Breast Cancer Awareness Month, a time when women’s breast health is a popular topic in the media.’s mission is to promote an informed “dense breast” conversation between patient and physician. In addition, the website provides medically-sourced tools to help women navigate through questions they have during breast health screenings.

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