Understanding breast cancer screening

In the United States, mammography is the gold standard for breast cancer screening. What can they detect?
Dr. Pinker-Domenig: Women at average risk for breast cancer are recommended to start with mammography, which is a low-dose x-ray that looks at breast tissue. The machine has two plates that compress the breast and spread out the tissue before taking the photo.

In addition to looking for masses, mammograms also look for details such as asymmetries and microcalcifications that may indicate something is growing in that spot.

There are different types of mammography. With a regular mammogram, which is 2D, the patient may be called back because there may be overlapping tissue and we don't know if it's something to be concerned about. Digital breast tomosynthesis, also called a 3D mammogram, is another type of mammogram that can reduce recall and detect more cancers.

The latest development is contrast-enhanced mammography, which uses dye injected into a vein to visualize cancer. This is a great option for women who are at higher risk than average and have dense breasts that limit mammography or even tomosynthesis. So this is a new and exciting addition to the screening toolbox that we have.

It's also important to note that self-breast exams are still valuable during the screening process, as they allow you to get to know your body. If you feel something is wrong, we recommend that you check it once.

When is additional screening, such as an ultrasound, required?
If a finding is detected on a mammogram, a diagnostic breast ultrasound is often done as part of the workup. However, ultrasound can also be used as an adjunct screening for women with dense breasts.

Although ultrasound can help find more cancers, it can also cause more false positives. Sometimes I get asked, “Can I have an ultrasound instead of a mammogram?” The answer is no. Ultrasonography cannot detect microcalcifications, which are often the earliest form of breast cancer. Ultrasound alone is not an adequate screening test.

Who is recommended to have an MRI scan and how is it used for screening?
MRI is undoubtedly the most sensitive test for detecting breast cancer, regardless of risk factors such as breast density. However, MRI is also the most expensive test. It is currently recommended for patients at high risk for breast cancer, including those with a lifetime risk of 20% or higher. Standard screening for these high-risk women is MRI and mammography. This is because MRI can miss early, small cancers that appear as microcalcifications on mammograms. Patients undergoing mammography or MRI do not require an ultrasound.

How does breast MRI work?
Breast MRI is a device that uses a powerful magnet and radio waves to create detailed images of the inside of the breast. Similar to contrast-enhanced mammography, breast MRI uses dye injected into a vein to highlight areas where cancer is growing. Unlike a mammogram, an MRI does not use radiation and is completely painless. You lie still inside a tunnel-like scanner. However, if you are claustrophobic and don't like closed spaces, you may feel a little uncomfortable inside.

In what scenarios would a doctor perform a biopsy?
A scenario in which a biopsy is recommended is when there is suspicion of malignancy. I usually advise patients not to assume they have cancer right away. If there is more than a 2% chance of malignancy, we recommend a biopsy because we don't want to miss anything.

The initial biopsy is not a surgery. A radiologist uses image guidance and local anesthesia to remove and study small tissue samples. During the biopsy, you will feel the radiologist doing something, but it will not hurt. Personally, I compare it to a dentist.

Once the biopsy is complete, place a small clip marker over the area where the sample was taken. This is important because if it comes back benign, the person reading the mammogram in the future will know that a biopsy was done and the results were benign. If surgery is required, this will also help you know exactly where to go, allowing your surgeon to save as much tissue as possible. This marker does not detect metal detectors at airports and is non-allergenic.

What should I keep in mind about screening if I am attending screening for the first time, or in general?
If it's your first time taking a screening test, there's no need to panic right away if it's recalled. I don't have any old images to compare it to, so I want to see everything and document everything properly. So if you happen to have a recall on your baseline test, it doesn't necessarily mean you have cancer.

Patients also need to be aware that we err on the side of caution and want to catch cancer as early as possible. Currently, almost everything detected early is treatable. That's why it's so important to get a mammogram.