World Dense Breast Day 2026 is bringing renewed attention to a common breast characteristic that can affect both a woman’s risk of developing breast cancer and the ability of a mammogram to detect it.

Observed on September 30, the fifth annual World Dense Breast Day is a 24-hour global education campaign organized by DenseBreast-info.org. The effort brings together health organizations, clinicians and advocates to share medically sourced information about breast density, screening and breast cancer detection. DenseBreast-info.org said its 2025 campaign reached 53.6 million people worldwide and generated more than 76,000 interactions. DenseBreast-info, Inc.

The Black Women’s Health Imperative joined this year’s campaign as an event supporter, encouraging Black women to understand their breast density, personal risk and screening options.

“KNOW your breast density. KNOW your risk. KNOW your screening options,” the organization wrote in a World Dense Breast Day message, while encouraging women to discuss appropriate screening with their health care providers.

Breast density describes the amount of fibrous and glandular tissue compared with fatty tissue in the breast. It is not something a person can determine by looking at or feeling the breast. A radiologist determines breast density by examining a mammogram.

Dense breasts are also common. The National Cancer Institute estimates that nearly half of women age 40 and older who receive mammograms have dense breast tissue. Cancer.gov

The issue matters for two reasons. Dense breast tissue and tumors can both appear white on a mammogram, making some cancers more difficult to see. Separately, having dense breasts is itself associated with an increased risk of developing breast cancer, although breast density is only one of several factors that determine a person’s overall risk. CDC

Knowing breast density is only the first step

Since September 10, 2024, mammography facilities across the United States have been required under updated Food and Drug Administration regulations to tell patients about their breast density in mammography reports. The federal standard requires reports to classify breast density and explain that dense tissue can make cancer more difficult to detect on a mammogram. U.S. Food and Drug Administration

That change means more patients now receive breast-density information, but understanding what to do with it remains important.

The U.S. Preventive Services Task Force recommends mammography every two years for women ages 40 through 74 who are at average risk. For women with dense breasts and an otherwise negative mammogram, however, the Task Force says current evidence is insufficient to recommend either for or against supplemental screening with ultrasound or MRI. Patients are encouraged to discuss their breast density alongside other risk factors with a health care professional when considering additional imaging. USPSTF

DenseBreast-info.org Executive Director JoAnn Pushkin said the campaign is intended to help women have those conversations with reliable information.

“The goal is to Find It Early, when cancer is the most treatable and survivable,” Pushkin said in announcing this year’s campaign. DOTmed

That conversation carries particular importance for Black women because breast cancer outcomes continue to differ sharply across racial groups. American Cancer Society data show that Black women have a lower overall breast cancer incidence rate than White women but a 38% higher breast cancer death rate. The organization points to differences in stage at diagnosis and access to high-quality screening and treatment as contributing factors. American Cancer Society

The USPSTF has similarly noted that Black women are more likely to be diagnosed beyond stage I and more likely to develop triple-negative breast cancer, an aggressive subtype. The Task Force has emphasized that screening alone is not enough to address these differences and that timely follow-up after an abnormal mammogram and access to effective treatment are also essential. USPSTF

World Dense Breast Day organizers are using this year’s campaign to make breast-density information more understandable before Breast Cancer Awareness Month begins in October. For patients who receive a dense-breast notification, experts say the result should not be viewed as a diagnosis. Instead, it can serve as a starting point for understanding individual breast cancer risk, staying current with recommended mammography and discussing whether any additional evaluation is appropriate.

For many women, knowing their breast density may be one more piece of information that helps them take a more informed role in their breast health.