Doctors usually diagnose patients with breast cancer after taking a tissue sample, which can require minor surgery in some cases.
Patients are ranked by categories of severity. A level 0 (zero) is the lowest category and has a 100 percent survival rate when treated. Level IV (four) is the most advanced level and has a significantly lower survival rate.
Doctors use many tests to diagnose cancer and find out if the cancer has spread or metastasized to other parts of the body beyond the breast and the lymph nodes under the arm. Some tests may also help the doctor decide which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. A biopsy is the removal of a small amount of tissue or cells for examination under a microscope. See below for more information about the types of biopsies that can be performed. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has spread.
This list describes options for diagnosing this type of cancer, and not all tests listed will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:
Age and medical condition
Type of cancer suspected
Signs and symptoms
Previous test results
The series of tests needed to evaluate a possible breast cancer usually begins when a woman or her doctor discover a mass or abnormal calcifications on a screening mammogram, or a lump or nodule in the woman’s breast during a clinical or self-examination. Less commonly, a woman might notice a red or swollen breast or a mass or nodule under the arm.
The following tests may be used to diagnose breast cancer or for follow-up testing after the cancer has been diagnosed. Not every person will need all of these tests.
The following imaging tests may be done to learn more about a suspicious area found in the breast during screening.
Diagnostic mammography. Diagnostic mammography is similar to screening mammography except that more pictures of the breast are taken, and it is often used when a woman is experiencing signs, such as a new lump or nipple discharge. Diagnostic mammography may also be used if something suspicious is found on a screening mammogram.
Ultrasound. Anultrasound uses high-frequency sound waves to create an image of the breast tissue. An ultrasound can distinguish between a solid mass, which may be cancer, and a fluid-filled cyst, which is usually not cancer.
MRI. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. An MRI can also be used to measure the tumor’s size. A special dye called a contrast medium is given into the patient’s vein before the scan to help create a clear picture of the possible cancer. A breast MRI may be used after a woman has been diagnosed with cancer to check the other breast for cancer or to find out how much the disease has grown throughout the breast. It may also be used for screening, along with mammography, for some women with a very high risk of developing breast cancer (see Prevention).
A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. There are different types of biopsies, classified by the technique and/or size of needle used to collect the tissue sample.
A fine needle aspiration biopsy uses a thin needle to remove a small sample of cells.
A core needle biopsy uses a wider needle to remove a larger sample of tissue. This is usually the preferred biopsy technique for finding out whether an abnormality on a physical examination or an imaging test is cancer. A vacuum-assisted biopsy removes several large cores of tissue. Local anesthesia, which is medication to block pain, is used to lessen a patient’s discomfort during the procedure.
A surgical biopsy removes the largest amount of tissue. This biopsy may be incisional, which is the removal of part of the lump, or excisional, which is the removal of the entire lump. Because surgery is best done after a cancer diagnosis has been made, a surgical biopsy is usually not the recommended way to diagnose breast cancer. Most often, non-surgical core needle biopsies are recommended to diagnose breast cancer. This means that only one surgical procedure is needed to remove the tumor and to take samples of the lymph nodes.
Image-guided biopsy is used when a distinct lump cannot be felt, but an abnormality is seen with an imaging test, such as a mammogram. During this procedure, a needle is guided to the location with the help of an imaging technique, such as mammography, ultrasound, or MRI. A stereotactic biopsy is done using mammography to help guide the needle. A small metal clip may be put into the breast to mark where the biopsy sample was taken, in case the tissue is cancerous and more surgery is needed. This clip is usually titanium so it will not cause problems with future imaging tests, but check with your doctor before you have additional imaging tests. An image-guided biopsy can be done using a fine needle, core, or vacuum-assisted biopsy (see above), depending on the amount of tissue being removed. Imaging tests may also be used to help do a biopsy on a lump that can be felt, in order to help find the best location.
Sentinel lymph node biopsy is a way to find out if there is cancer in the lymph nodes near the breast. Learn more about sentinel lymph node biopsy in the Treatment Options section.
Analyzing the sample(s) removed during the biopsy can help your doctor learn about specific features of a cancer that help determine treatment options.
Tumor features. Examination of the tumor under the microscope is used to determine if it is invasive or in situ, ductal or lobular, and whether the cancer has spread to the lymph nodes. The margins or edges of the tumor are also examined and their distance from the tumor is measured, which is called margin width.
ER and PR. Testing for ER and PR (see Overview) helps determine both the patient’s risk of recurrence and the type of treatment that is most likely to lower the risk of recurrence. ER and PR are often measured for DCIS as well. Generally, hormonal therapy (see Treatment Options) works well for ER-positive and/or PR-positive cancers. Learn about ER and PR testing recommendations from ASCO and the College of American Pathologists (CAP).
HER2. The HER2 status (see Overview) helps determine whether drugs that target the HER2 receptor, for example the antibody treatment trastuzumab (Herceptin), might help treat the cancer. In addition, about 50% of HER2-positive tumors also have hormone receptors and can benefit from both hormone and HER2 directed therapy. Read ASCO’s and CAP's recommendations for HER2 testing for breast cancer
Grade. The tumor grade is also determined from a biopsy. Grade refers to how different the cancer cells look from healthy cells, and whether they appear slower growing or faster growing. There are three grades: grade 1 (well differentiated), grade 2 (moderately differentiated), and grade 3 (poorly differentiated).
Your doctor may recommend additional laboratory tests on your tumor sample to identify specific genes, proteins, and other factors unique to the tumor. This helps your doctor find out the subtype of cancer.
Tests that take an even closer look at the biology of the tumor are commonly used to understand more about a woman’s breast cancer, particularly for a cancer that has not spread to other organs. These tests can help estimate the risk of cancer recurrence in the years after diagnosis. They can also predict whether a treatment will be helpful to reduce the risk of cancer recurrence. This helps some patients avoid the possible side effects of a treatment that is not likely to work well.
The tests described below are typically done on tissue removed during surgery. Most patients will not need an extra biopsy or more surgery. For more information about genomic tests, what they mean, and how the results might affect your treatment plan, talk with your doctor.
Oncotype Dx™. This test evaluates 16 cancer-related genes and 5 reference genes to estimate the risk of the cancer coming back in a place other than the breast and nearby lymph nodes within 10 years after diagnosis for women with stage I or stage II (see Stages) ER-positive breast cancer treated with hormonal therapy alone. Results are mainly used to help make decisions about whether chemotherapy should be added to a person’s treatment with hormonal therapy. Although this test is typically used for patients with breast cancer that has not spread to the lymph nodes, recent research suggests that this test may be useful for some patients with cancer that has spread to the lymph nodes.
Mammaprint™. This test uses information from 70 genes to predict the risk of the cancer coming back for early-stage, low-risk breast cancer. It is approved by the FDA for estimating the risk of recurrence in early-stage breast cancer, but it is not yet known if this test can predict whether chemotherapy will work. This test is more common in Europe than in the United States.
Additional tests. Other tests are being researched and may become additional tools to guide treatment options in the future. These tests include the following, among others:
Breast cancer index (BCI)
The doctor may also need to do several types of blood tests to learn more about the cancer:
Complete blood count. A complete blood count (CBC) is used to measure the number of different types of cells, such as red blood cells and white blood cells, in a sample of a person’s blood. It is done to make sure that your bone marrow is functioning well.
Serum chemistry. These tests are often done to look at minerals in your blood, such as potassium and calcium, called electrolytes and specialized proteins called enzymes that can be abnormal if cancer has spread. However, many noncancerous conditions can cause changes in these tests, and they are not specific to cancer.
Alkaline phosphatase is an enzyme that can be associated withdisease that has spread to the liver, bone, or bile ducts.
Blood calcium levels can be high if cancer has spread to the bone.
Total bilirubin count and the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST)evaluate liver function. High levels of any of these substances can indicate liver damage, a sign that the cancer may have spread to that organ.
Hepatitis tests. These may be used to check for evidence of prior exposure to hepatitis B and/or hepatitis C. If you have evidence of an active hepatitis B infection, you may need to take a special medication to suppress the virus before you receive chemotherapy. Without this medication, the chemotherapy can help the virus to grow and cause damage to the liver.
Blood tumor marker tests. Serum tumor markers are tumor proteins in a person's blood. Higher levels of a serum tumor marker may be due to cancer or a noncancerous condition. Tumor marker testing is not recommended for early-stage breast cancer because the markers are not usually high, but they may be useful to monitor the growth of recurrent or metastatic disease along with symptoms and imaging tests. Tumor markers should not be used to monitor for a recurrence, as such testing does not appear to improve a patient’s chance of recovery. Learn more about tumor markers for breast cancer
The tests your doctor recommends to evaluate whether the cancer has spread and its stage depends on your medical history, symptoms, how much the disease has grown in the breast and lymph nodes, and the results of your physical examination. Read Stages for more information. Many of these tests may not be done until after surgery. These tests are generally only recommended for patients with later-stage disease. Most patients with early-stage breast cancer do not need additional imaging tests.
X-ray. An x-ray is a way to create a picture of the structures inside of the body, using a small amount of radiation. A chest x-ray may be used to look for cancer that has spread from the breast to the lungs.
Bone scan. A bone scan may be used to look for spread of cancer to the bones. A radioactive dye or tracer is injected into a patient’s vein, and then the scan is performed several hours later using a special camera. The tracer collects in areas of the bone that are healing, which occurs in response to damage from the cancer cells. The areas where the tracer collects appear dark, compared to healthy bone, which appears gray. Some cancers do not cause the same healing response and will not show up on the bone scan. Areas of advanced arthritis or healing after a fracture will also appear dark.
Computed tomography (CT or CAT) scan. A CT scan may be used to look for tumors in organs outside of the breast, such as the lung, liver, bone, and lymph nodes. A CT scan creates a three-dimensional picture of the inside of the body with a special x-ray machine. A computer combines these images into a detailed, cross-sectional view that shows abnormalities, including most tumors. A CT scan can also be used to measure the tumor’s size and if it is shrinking with treatment. A contrast dye may be injected into a patient’s vein before the scan to provide better detail.
Positron emission tomography (PET) scan. A PET scan may also be used to find out whether the cancer has spread to organs outside of the breast. Similar to a CT scan, a PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into a patient’s vein. This sugar substance is then taken up by cells that use the most energy because they are actively dividing. Because cancer cells tend to use energy actively, they absorb more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body. Areas that are most active appear as bright spots, and the intensity of the brightness can be measured to better describe these areas. A combination PET/CT scan may also be used to measure the size of tumors and to determine the location of the bright spots more accurately. A PET/CT scan will also show any abnormalities in the bone, similar to the bone scan.
After diagnostic tests are completed, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the amount of cancer in the body; this is called staging. If there are suspicious areas found outside of the breast, at least one area may be biopsied if possible to confirm the diagnosis of cancer.