June 27, 2019
3 min read

Dense breast notification laws with added mandate linked to increased ultrasound, cancer detection rates

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact customerservice@slackinc.com.

Susan Busch, PhD
Susan Busch

State-mandated breast density notifications that included information about the benefits of supplemental screening appeared associated with modest increases in ultrasound use and cancer detection rates, according to study results.

“Our study suggests that if one of the goals of dense breast notification laws is to change clinical practice, the language of the legislation is important,” Susan Busch, PhD, professor of public health at Yale University School of Public Health, said in a press release. “Including specific information about additional testing is more effective than vague recommendations that suggest talking to your physician.”

Busch and colleagues assessed the association of state dense breast notification laws with supplemental testing and cancer detection by reviewing data from more than 1.4 million mammograms performed in 2014 and 2015 among women aged 40 to 59 years with private insurance. The women resided in nine U.S. states that enacted dense breast notification laws and 25 U.S. states without such laws.

Results showed states with dense breast notification laws that also required notice of possible supplemental screening benefits had 10.5 more ultrasounds per 1,000 mammograms and 0.37 more breast cancers detected per 1,000 mammograms than states without notification laws. Researchers observed no significant differences in ultrasound and cancer detection rates between states with generic notifications and no notifications.

Busch spoke with HemOnc Today about the differences in dense breast notification laws, their apparent impact on further screening and cancer detection, and plans for subsequent research.

Question: What prompted this research?

Answer: Dense breast notification laws typically require that mammogram reports provided to women include information regarding breast density. Yet, states differ in the specifics. Almost all state notification laws suggest communication with a provider, such as: ‘This information about the results of your mammogram is given to you to raise your awareness and to inform your conversations with your doctor. Together, you can decide which screening options are right for you.’

However, some states require that information about the potential benefits of supplemental screening be included in the notification. For example, ‘You may benefit from supplemental screening tests, which may include breast ultrasound screening, breast MRI examination or both, depending on your individual risk factors.’ Although past reports indicated use of supplemental ultrasound increased in certain states after introduction of dense breast notification laws, whether these laws were associated with population-level changes in breast cancer detection was unknown. In addition, we were interested in learning whether the content of the notification affected the magnitude of any changes in the supplemental screening rate.


Q: How did you conduct the study?

A: Using health care claims data, we conducted a retrospective study of women aged 40 to 59 years receiving a screening mammography. We then looked at the associations between two categories of state dense breast notification laws and receipt of supplemental screening (ultrasound or MRI), or breast biopsy, and cancer detection. Given the strong association between breast density and age, we also assessed potential differences in such effects by age at mammography.

Q: Can you elaborate on the findings ?

A: Although dense breast notification laws were associated with increased ultrasound rates, the increases were not significant — about 10 per 1,000 screening mammograms. Only laws that included language about the benefits of supplemental testing were associated with increased screening ultrasound. Our study adds to prior work in that we also examined the association of dense breast notification laws with breast cancer detection. We found that dense breast notification laws were associated with small increases in cancer detection but, again, only in states with laws that included language about the benefits of supplemental testing.

Q: Were you surprised by what you found?

A: We were surprised that the increase in rates of screening ultrasound was small. I would have expected to see a greater increase in supplemental ultrasound screening, given that dense breasts are common in women in their 40s and 50s (between 38% and 57% of these women have dense breasts).

Q: What are the clinical implications of the findings?

A: If women are notified that they have dense breasts, they should consider discussing the benefits and risks of supplemental screening with their physician. Physicians may consider a patient’s individual risks for breast cancer and provide information on the benefits of supplemental screening. This will help women decide on a screening strategy tailored to their individual risk factors and preferences.

Q: Do you have plans for additional research?

A: Yes. We are interested in whether dense breast notification laws have the intended effect of increasing women’s awareness of breast density, including the possible masking effects of dense breasts, and the increased risk for breast cancer. In addition, we are interested in examining potential harms of the notices, including whether women experienced increased anxiety in states with dense breast notification laws.

Q: Is there anything else that you would like to mention?


A: We did not have enough follow-up data in our study to determine whether dense breast notification laws were associated with reduced breast cancer mortality. This is another area that deserves additional study. – by Jennifer Southall


Busch SH, et al. Am J Public Health. 2019;doi:10.2105/AJPH.2019.304967.

For more information:

Susan H. Busch, PhD, can be reached at Yale University School of Public Health, 60 College St., PO Box 208034, New Haven, CT 06520-8034; email: susan.busch@yale.edu.

Disclosure: Busch reports no relevant financial disclosures.