How Is Breast Cancer Diagnosed?

Reviewed by: HU Medical Review Board | Last reviewed: February 2024 | Last updated: February 2024

A breast cancer diagnosis may require several tests and different doctors. The path to a diagnosis may begin with regular screening tests. Doctors use regular screening to detect breast cancer before it causes any symptoms. Your doctor may also suggest additional testing if you or the doctor find a lump or notice other breast changes.1,2

Screening for breast cancer

X-rays of the breast, called mammograms, are an important part of breast cancer screenings. In a mammogram, the breast is placed between a platform and a plastic plate. It is then compressed to evenly distribute the tissue and hold the breast still.1-3

It is recommended that women ages 45 to 54 get mammograms every year. Women 55 and older can often get mammograms every 2 years. Some women may need additional screening tests because of their genetics or family history. You should also monitor your breasts for any visual changes.1,2

Your doctor may start diagnostic testing if:1,2

  • A mammogram shows signs of breast cancer
  • You notice a change in your breasts

How are imaging tests used to diagnose breast cancer?

Imaging tests help doctors see inside the body. There are several imaging tests that may be used to get a clearer view of your breast tissue:1,3

  • Diagnostic mammograms are similar to screening mammograms except that the picture is more detailed.
  • Ultrasounds help show the difference between masses or cysts. Masses are more likely to be cancer than cysts. Ultrasounds are usually used to look at a small area rather than the entire breast.
  • Magnetic resonance imaging (MRI) uses magnets to make detailed images of the body. You may be injected with a dye before the MRI scan begins. The dye helps the cancer show up better on the images. MRIs may also be used after diagnosis to determine if cancer has spread.

How are biopsies used to diagnose breast cancer?

During a biopsy, a small piece of tissue is removed from the breast. An expert then looks at this tissue with a microscope. Imaging tests can show something in the body that might be cancer. But you typically need a biopsy to confirm a diagnosis.1,3

There are different types of biopsies that might be used:1,3

  • Fine needle biopsies use a small needle and only remove a sample of cells.
  • Core needle biopsies use a wider needle to remove a tissue sample.
  • Image-guided biopsies use imaging to help your doctor guide the needle to a specific spot.
  • Surgical biopsies remove the largest amount of tissue. This is a less common type of biopsy for diagnosing breast cancer.
  • Sentinel lymph node biopsies check to see if cancer has spread to lymph nodes near the breasts.

Classifying breast cancer

If you have breast cancer, the tissue sample from your biopsy can tell your doctor more about the cancer. They may do additional tests on the sample. This can help your doctor to learn which treatments may be most effective for your cancer. The tests may check for:1,4

  • Certain hormone receptors or proteins.
  • Changes (mutations) in your genes.
  • How different the cancer cells look from healthy cells. This is called the grade.

These tests help your doctor decide treatment options and determine the risk from the cancer. You may also receive a blood test. Blood tests can check for blood cell counts, organ health, and tumor markers.1,4

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