The process of diagnosing breast cancer usually begins when a woman or her doctor discovers an abnormality in the breast during a clinical or self-examination or when
a mass or tiny spots of calcium appear on a screening mammogram. After this, the doctor will use a number of tests and procedures to determine whether the mass is cancerous and, if it is, to figure out if the cancer has spread.
Not every test is right for every person. Your doctor may consider factors such as your age, medical condition, signs and symptoms, and previous test results when deciding whether a specific diagnostic test is right for you.
- Diagnostic mammography
Mammography is a type of x-ray designed to view the breast. The x-ray films produced by mammography, called mammograms, help doctors find small tumors or irregularities in the breast. Diagnostic mammography is similar to screening mammography except that more pictures are taken, and it is often used when a woman is experiencing signs, such as nipple discharge or a new lump. Diagnostic mammography may also be used if something suspicious is found on a screening mammogram.
An ultrasound 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.
- Magnetic resonance imaging (MRI)
An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. An MRI can also be used to measure a tumor’s size. A special dye called a contrast medium is injected into a patient’s vein or given as a liquid to swallow before the scan to help create a clearer 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 before surgery to find out if chemotherapy is working to shrink the tumor.\
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. There are different types of biopsies, classified by the technique and/or size of the needle used to collect the tissue sample.
- Fine needle aspiration biopsy
This type of biopsy uses a thin needle to remove a small sample of cells from a suspicious lump.
- Core needle biopsy
This procedure uses a thicker needle to remove a larger sample of tissue. It is usually the preferred biopsy technique to find out whether an abnormality discovered during a physical examination or on an imaging test is cancer. A vacuum-assisted biopsy removes several large cores of tissue. Medication to block the awareness of pain, called local anesthesia, is used to reduce a person’s discomfort during the procedure.
- Image-guided biopsy
This test is done when a distinct lump can’t be felt, but an abnormality is seen with an imaging test, such as on a
mammogram. An image-guided biopsy can be done using a fine needle, core needle, or vacuum-assisted needle, depending on the amount of tissue that needs to be removed. During the procedure, the needle is guided to the best 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 any additional tests or scans.
- Surgical biopsy
This type of biopsy removes the largest amount of tissue. A surgical biopsy is either incisional if it removes part of the lump or excisional if it removes the entire lump. Because
surgery is best done after a cancer diagnosis has been made, a surgical biopsy is usually not the recommended procedure for diagnosing breast cancer. Most often, non-surgical core 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.
After a biopsy, a pathologist will look very closely at the tissue that was removed using a microscope. Based on this examination, the pathologist can tell which area of the
breast the cancer started in (ductal or lobular), whether the tumor has spread outside this area (invasive or in situ), and how different the cancer cells look from healthy breast cells (the grade). If the tumor was removed, the healthy tissue around the edges of the tumor, called the margins, will
also be examined to see if cancer cells are present and to measure their distance from the tumor, which is referred to as the margin width.
Additional laboratory testing will be performed on the tumor sample removed during a biopsy. This is done to identify specific genes, proteins, and other factors unique to your tumor. The standard tests used to further evaluate invasive breast cancer include estrogen receptor (ER), progesterone receptor (PR), and HER2 tests. ER status is often determined for DCIS as well.
- ER and PR status
About 60% to 75% of breast cancers have estrogen and/or progesterone receptors. Breast cancer cells with these receptors depend on the hormones estrogen and/or progesterone to grow. The presence of these receptors helps determine the risk of the cancer coming back after treatment and the type of treatment most likely to lower this risk. Generally, hormonal therapy works well for ER-positive and/or PR-positive cancers, also called hormone receptor- positive cancers.
- HER2 status
About 20% to 25% of breast cancers have more copies than usual of a gene called the human epidermal growth factor receptor 2 (HER2). Because this gene makes a protein that fuels tumor cell growth, HER2-positive cancers may grow more quickly. The tumor’s HER2 status also helps determine whether drugs that target the HER2 might help treat the cancer. These drugs include trastuzumab (Herceptin), pertuzumab (Perjeta), lapatinib (Tykerb), and neratinib (Nerlynx). About 50% of HER2-positive tumors also have hormone receptors, so patients can benefit from both types of treatment.
If a tumor does not express ER, PR, or HER2, the tumor is called “triple-negative.” Triple-negative breast cancer makes up about 15% of invasive breast cancers. Triple-negative
breast cancer may be more common among younger women, particularly younger black women. Triple-negative cancer is also more common in women with a mutation
in the BRCA1 and BRCA2 genes. Experts recommend that all people with triple-negative breast cancer be tested for BRCA gene mutations.
Tests that look at the biology of a tumor are sometimes used to understand more about breast cancer, especially if the cancer has not spread to other parts of the body. These tests can help choose the most effective type of treatment, predict the risk of recurrence, and avoid possible side effects of a treatment that is not likely to work well.
The most common genomic test in the United States is called 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.
This test is usually used for patients with stage I or stage II ER-positive breast cancer. These results are mainly used to help doctors decide whether chemotherapy should be added to treatment with hormonal therapy.
There are other types of genomic tests that are less often used. These include Breast Cancer Index, MammaPrint, and Prosigna (formerly called a PAM50 test).
Doctors may also use the term “grade” when talking about breast cancer. The grade describes how much cancer cells look like healthy cells when viewed under a microscope. Knowing the grade of the cancer may help your doctor predict how quickly the cancer will spread. If the cancer looks similar to healthy tissue and contains different cell groupings, it is called differentiated or a low-grade tumor. If the cancerous tissues look very different from healthy tissue, it is called poorly differentiated or a high-grade tumor. In general, the lower the tumor’s grade, the better the prognosis.
- GX—Cannot be evaluated; undetermined
- G1—Similar to healthy breast tissue, well differentiated, low grade
- G2—Still has some features of healthy breast tissue, moderately differentiated, intermediate grade
- G3—Very different from healthy breast tissue, poorly differentiated, high grade
People with breast cancer are usually given a stage along with their diagnosis. The stage is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body. Doctors use diagnostic tests to find out a cancer’s stage so information about staging may not be available until all the tests are finished. Knowing the stage will help your doctor decide which treatment plan will be most effective and help predict your prognosis.
Doctors assign the stage of breast cancer using a number zero (0) through 4 (Roman numerals I through IV). Doctors may refer to stage I and stage IIA cancer as “early stage” and to stage IIB and stage III as “locally advanced.” Stage IV is called “metastatic breast cancer.”
Stage 0. The disease is only in the ducts and/or lobules of the breast and has not spread to the surrounding breast tissue. It is also called in situ or noninvasive cancer.
Stage IA. The tumor is small and invasive, but it has not spread to the lymph nodes.
Stage IB. A small number of cancer cells have spread to the axillary lymph nodes under the arm and formed tiny clusters larger than 0.2 mm but smaller than 2 mm in size. There is either no evidence of a tumor in the breast, or the tumor in the breast is 20 mm or smaller.
Stage IIA. The cancer has any of the following characteristics:
- There is no evidence of a tumor in the breast, but there is cancer in the axillary lymph no
- The tumor is 20 mm or smaller and has spread to the axillary lymph nod
- The tumor is between 20 mm and 50 mm and has not spread to the axillary lymph no
Stage IIB. The cancer has either of the following characteristics:
- The tumor is between 20 mm and 50 mm and has spread to 1 to 3 axillary lymph no
- The tumor is larger than 50 mm but has not spread to the axillary lymph nod
Stage IIIA. The tumor may be any size, but it has spread to 4 to 9 axillary lymph nodes or to internal mammary lymph nodes. It has not spread to other parts of the body.
Stage IIIA may also describe a tumor larger than 50 mm that has spread to small areas of cancer in the lymph nodes.
Stage IIIB. The tumor has spread to the chest wall, caused swelling or ulceration of the breast, or is diagnosed as inflammatory breast cancer. It may or may not have spread to the axillary or internal mammary lymph nodes under the arm. It has not spread to other parts of the body.
Stage IIIC. The tumor can be any size, but it has spread to 10 or more axillary lymph nodes, the internal mammary lymph nodes, and/or other lymph nodes under the collarbone. The cancer has not spread to other parts
of the body.
Stage IV. The tumor can be any size, but the distinguishing characteristic is that it has spread to other distant sites in the body.
Recurrent. The breast cancer has come back after treatment.
STAGE AND GRADE
- Stage 0 ¨ Stage IIIA
- Stage IA ¨ Stage IIIB
- Stage IB ¨ Stage IIIC
- Stage IIA ¨ Stage IV (metastatic)
- Stage IIB ¨ Recurrent