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  • Dense breast tissue can make it more difficult to detect signs of breast cancer on a mammogram.
  • Supplemental screening with an ultrasound can help increase breast cancer detection.
  • However, a new study has found that women at greatest risk are not always getting this additional screening.
  • While breast density is a risk factor, it’s important to consider other factors too.
  • Women with a high risk of mammography failure should consider supplemental screening.

Dense breast tissue is a risk factor for breast cancer. It makes it harder to visualize cancer on a mammogram, allowing critical diagnoses to be missed.

Currently, if you have dense breast tissue — in other words, your breasts contain proportionally more fibrous tissue than fat — doctors in the majority of states are required to notify you, in order to give women the opportunity to opt for supplemental ultrasound screening.

Now a new study published in the journal CANCER finds there are some potential drawbacks to supplemental screenings according to the authors of a study.

First of all, additional imaging is needed so there is more time and expense involved.

Also, more ultrasounds mean that there is a higher likelihood that people will end up having unneeded breast biopsies.

The authors note that it is important to be certain that only women who are at high risk of missed breast cancer diagnoses are getting supplemental ultrasound screening.

The goal of their study was to evaluate the risks versus benefits of these added screenings.

The American College of Gynecology and Obstetrics released updated guidance for healthcare practitioners and reiterated that women with dense breasts but no additional risk factors for cancer may not need additional screenings.

“While ACOG does not recommend routine use of alternative or adjunctive tests to screening mammography in individuals with dense breasts who are asymptomatic and have no additional risk factors, ACOG recommends that clinicians comply with the new FDA rule and any state laws and federal rules that require disclosure of a patient’s breast density as recorded in a mammogram report,” the authors stated.

According to Dr. Blen Tesfu, a general practitioner and medical advisor for the UK-based healthcare platform Welzo, ultrasound’s ability to visualize the breast in a different way can provide additional information to doctors.

“It can detect small abnormalities that might not be visible on mammograms alone,” she explained, “potentially leading to earlier detection and improved outcomes for women at higher risk.”

Lead author Dr. Brian Sprague said he and his colleagues were interested in studying this topic because there are no national guidelines for when to use supplemental screening after a mammogram.

“Yet, the use of breast ultrasound screening has been increasing over the past decade in the U.S.,” he noted, “in part due to the increased attention to the limitations of mammography screening among women with mammographically dense breasts.”

To take a closer look at this question, he and his team examined altogether 38,166 supplemental ultrasounds and 825,360 screening mammograms without supplemental ultrasounds.

Their analysis was performed between 2014 and 2020 at 32 American imaging facilities and three regional registries of the Breast Cancer Surveillance Consortium.

When they analyzed the data, they found that 95.3% of supplemental ultrasounds were being done on women with dense breast tissue.

On the other hand, 41.8% of mammograms without supplemental ultrasound screening were done in women with dense breasts.

Among the women who received supplemental ultrasound screening, 23.7% had a high risk of interval-invasive breast cancer, meaning that cancer missed by the screening would be detected prior to the next regularly scheduled mammogram.

This was compared to 18.5% of women who had mammograms that were not followed up with supplemental ultrasound imaging.

Interval-invasive cancers tend to grow and spread quickly as well as being larger, per the National Cancer Institute. They also have a worse prognosis.

Sprague said these findings suggest that ultrasound screening is highly targeted to women with dense breasts, but not well targeted to women who are at the highest risk of a missed diagnosis.

Tesfu said, based on this study, it is advised for supplemental ultrasound screening to be done on women with dense breasts who are also at high risk of mammography screening failure.

“Factors to consider when determining high-risk status may include breast density and 5-year breast cancer risk calculated using prediction models,” she said.

However, because no consensus guidelines currently exist, the assessment will have to be done on a case-by-case basis, taking into account each woman’s risk factors, preferences, and available resources.

Sprague pointed to publicly available risk calculators from the Breast Cancer Surveillance Consortium that consider factors such as age, family history of breast cancer, body mass index, breast density, as well as others, which can be used in decision-making.

“Women with breast cancer risk and particularly those at high risk of a late stage breast cancer with mammography alone should consider supplemental ultrasound screening,” he advised.

Tesfu said that consultation with your healthcare provider or a breast specialist will help you determine what is appropriate for you.