How is Breast Cancer Diagnosed?

Last updated: September 2023

A diagnosis of breast cancer may require several tests and the expertise of different doctors. The journey to a diagnosis may begin through regular screening tests, which are used to detect breast cancer before it causes any symptoms, or it may begin when a woman or her doctor find a lump or notice other breast changes that need further testing.

Screening tools

Mammograms are currently the best screening tool to detect breast cancer in its earliest stages. Mammograms are x-rays taken of the breasts. The breast is placed between a specific platform and a plastic plate, then compressed to evenly distribute the breast tissue and hold the breast still for the x-ray image. One image is taken from a top-to-bottom view, and one image is taken from an angled side view.1,2

Recommendations for screening mammography can vary for women between the ages of 40-49. However, certain screening guidelines suggest that women who are at an average risk of developing breast cancer begin screening mammography between the ages of 40-49 (and by no later than age 50) and receive yearly or biennial (every other year) mammograms between the ages of 50 and 74. For women at a higher risk for breast cancer, such as those with a personal or family history of breast cancer, or those who have a known genetic mutation (like BRCA), screening mammograms may be started at a younger age and/or recommended more frequently.3,4
Patients should discuss their individual screening plan with their doctor to determine the risks/benefits of screening options and to ensure they have the best plan for them as an individual.

Screening guidelines generally no longer recommend clinical breast exam (an examination of the breasts by a healthcare professional) or breast self-exam as effective screening tools, but some women or their doctors are the first to find an abnormality in the breast that may lead to a diagnosis of breast cancer.5 While mammography remains the best screening tool to find breast cancers at their earliest stages, it is important for all women to know what’s normal for their breast tissue and bring any changes to the attention of their doctor.

Diagnostic tools

There are several tools which may be used in diagnosing breast cancer, including:

  • Diagnostic mammograms, which are used when someone is having a symptom that may be indicative of breast cancer or if an abnormality was detected in a screening mammogram. Diagnostic mammograms use the same machine used in screening mammograms, but additional views are taken of the breast.6
  • Ultrasound, an imaging technique that uses sound waves to produce a picture and can help differentiate between a fluid-filled lump (such as a harmless cyst) or a solid lump.7
  • Magnetic resonance imaging (MRI), an imaging test that uses powerful magnets and radio waves to generate pictures of the internal structures and may be used on the breast to further evaluate abnormalities found on a mammogram or to determine the extent of a diagnosed breast cancer.8
  • Biopsy, a procedure in which a sample of tissue is removed from the breast to examine it for cancerous (malignant) cells under a microscope.9

Healthcare professionals involved in diagnosis

When getting a mammogram or other imaging, a patient will see a radiologist. A radiologist is a doctor who specializes in diagnosing conditions using medical imaging, such as mammograms, ultrasounds, and MRIs.10

Many women who have an abnormality found on a mammogram or who have a lump may be referred to a breast surgeon. While surgery may not be needed, a breast surgeon is a specialist in diagnosing breast conditions.11

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