How can we improve breast cancer screening?
Breast Cancer Cancer mammogram

How can we improve breast cancer screening?

Dr. Talia Henkle
Dr. Talia Henkle

In 10 seconds? Researchers have developed a new system to help identify women who have an increased risk of breast cancer and are good candidates to undergo additional screening.

What’s the story? Breast cancer is the number one cause of cancer death among women in the USA and much of the world. Cancer researchers are trying to change that. The earlier cancer is caught, the easier it is to treat. Mammogram screenings, which have been widely in use since the 1980s, have been key in helping clinicians detect breast cancers earlier and increase breast cancer survival rates.

Hang on! Can you remind me what mammograms are? Of course! A mammogram is a procedure that takes X-ray images of breasts and looks for changes, such as areas of increased density, that can indicate the presence of cancer. The United States Preventive Services Task Force recommends that women with average cancer risk aged 50-74 years be screened every two years. Conventionally, mammograms have been done with an X-ray machine that flattens the breast and takes 4 images of breast tissue in 2D. More recently, however, a new technology called digital breast tomosynthesis (DBT) has been developed. It takes hundreds of X-ray pictures of breast tissue and can render a higher-quality picture of the breast (and not to mention it doesn’t require the breast to be flattened, which can be uncomfortable).

Digital breast tomosynthesis (Right) renders a more detailed breast cancer image than standard digital mammography (left) Source: Altunkeser A, et al. Iran J Radiol. 2021;18(4):e113846.

So, what’s wrong with the screening guidelines? While breast cancer screening has saved many lives, mammograms still fail to detect about 15% of breast cancers or don’t catch them until a later stage, when they are harder to treat (and cancers are diagnosed at stage II or later, about 40% of the time). This is a problem because while the 3-year survival rate for Stage 0 and I breast cancers is higher than 99.7%, it falls to 96.4% for stage II and 83.1% for stage 3. Researchers estimate that this may be because the mammogram images mask some early-stage cancers or, alternatively because the cancers are grow quickly.

So, what can be done to improve mammogram screening and catch even cancers earlier? There is still some debate over what age groups should be screened and how frequently screening should occur, but these discussions fail to take breast cancer risk into account. Researchers have been trying to use refined scientific methods to identify people who have a high risk for breast cancer to encourage them to undergo additional screening measures like breast MRIs or ultrasounds (additional medical imaging techniques) that might help catch cancers that mammogram images miss.

And then what? It turns out that people with dense breast tissue have a 4-6x higher risk of developing breast cancer, which has led to many states requiring doctors to report breast density to women. This practice is a bit over-simplistic, however, as breast density is only one of many factors that impact breast cancer risk. And certainly, people with low breast density may still have a high breast cancer risk.

What else are they working on? Researchers have recently developed a new cancer risk model (AKA a formula that takes in patient data and spits out a cancer risk calculation) that was built off on data from digital breast tomosynthesis images of 154,000 women. This model did a better job at identifying women who had a high short-term risk of developing breast cancer (despite having received a negative screening result) than established risk models. This means that this method could potentially serve as an improvement to current standards and help more women catch their breast cancers earlier.

So, will this new risk analysis be used for patients? That requires a lot of steps! First, other research groups need to confirm these findings to ensure the risk model works as well as they claim. Next, come the logistical issues. Since digital breast tomosynthesis is relatively new, it is not widely accessible to women across the US, and even less so in low- and middle-income countries. Supposing that scenario improves, health insurance companies would also need to agree to cover the costs of any additional screening methods that the risk model recommends before these scientific advances can truly start to help women catch breast cancers early on a wide scale.

What’s the deal with dense breasts?

If you haven’t received a mammogram or if you live in a region that doesn’t report breast density findings, you’ve probably never considered breast density before.

Breasts are composed of three types of tissues, the proportions of which change over a person’s lifetime.

  1. Fatty tissue (AKA fat)
  2. Glandular tissue (Think: mammary glands that support lactation)
  3. Fibrous tissue (Think: scaffolding that supports the breast)

Breasts are considered 'dense' if they have a higher proportion of glandular and fibrous tissues. These sorts of tissues light up in X-ray images and may obscure any small tumors that are forming, which is why women with dense breasts may be recommended to undergo additional non-X-ray-based screening methods.

Dr. Talia Henkle has distilled 2 research papers saving you 7 hours of reading time.

The Science Integrity Check of this 3-min Science Digest was performed by Flávia Oliveira Geraldes.

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