Breast cancer is not a single disease. Different breast cancers can begin in different parts of the breast and may behave differently depending on the type of cancer, whether it has spread beyond where it started, and the biological characteristics of the tumor. Understanding these details helps your breast care team determine which treatment options are most appropriate for you.
At the Margie Petersen Breast Center, breast imaging specialists, pathologists, surgeons, medical oncologists and radiation oncologists work together to evaluate breast cancer and develop an individualized treatment plan based on the clinical findings.
About Breast Cancer
Breast cancer develops when abnormal breast cells begin growing and dividing without normal control. Most breast cancers begin in the milk ducts or the lobules that produce milk. Some remain confined to the structure where they began, while others become invasive and grow into surrounding breast tissue.
Breast cancer can occur in both women and men, although it is much more common in women. There are also many different types and subtypes of breast cancer, and their behavior can vary considerably. The location where the cancer began, whether it is invasive, its grade and stage, and characteristics such as hormone receptor and HER2 status all help define the diagnosis and guide treatment.
Learn more about the Types of Breast Cancer.
Signs and Symptoms of Breast Cancer
Early breast cancer often causes no noticeable symptoms, which is one reason regular breast cancer screening is important. When symptoms do occur, a new breast lump or area of thickening is one of the most common findings. Most breast conditions and changes are not cancer, but any new or persistent change should be evaluated rather than diagnosed based on symptoms alone.
Changes that should be evaluated include:
- A new lump or area of thickening in the breast or underarm
- Swelling of part or all of the breast, even when no distinct lump is felt
- A change in the size, shape or contour of the breast
- New dimpling, puckering or thickening of the breast skin
- Redness, swelling or skin that develops a pitted appearance similar to the surface of an orange
- A nipple that becomes newly inverted, flattened or pulled inward
- Spontaneous nipple discharge, particularly when it is clear or bloody
- Persistent crusting, scaling, ulceration or rash involving the nipple or areola
- Persistent focal pain or tenderness in the breast or nipple
Many benign conditions can also cause breast lumps, tenderness, nipple changes or changes in breast texture. These include cysts, fibroadenomas, fibrocystic changes, hormonal changes, infection and inflammation. Because symptoms alone cannot determine whether a change is benign or malignant, a new or persistent breast finding should be evaluated even if a recent screening mammogram was normal.
If you have noticed a new breast change, learn more about Breast Evaluation at the Margie Petersen Breast Center.
How Breast Cancer Is Diagnosed
Breast cancer may first be suspected because of an abnormal screening result or because a new breast change is found by a patient or healthcare provider. Evaluation typically begins with a clinical breast examination and diagnostic imaging selected according to the type of abnormality, the patient’s age and other clinical factors.
If imaging identifies an area that requires further evaluation, a breast biopsy may be performed to obtain tissue for examination by a pathologist. A biopsy is the only way to confirm whether breast cancer is present. The amount and type of tissue collected depend on the abnormality being evaluated, and many breast biopsies can be performed using a needle guided by mammography, ultrasound or MRI.
When cancer is confirmed, the pathology report provides additional information about the tumor that helps the breast care team understand the diagnosis and plan treatment. This may include the type of breast cancer, whether it is invasive, the tumor grade and important biomarkers such as estrogen receptor, progesterone receptor and HER2 status.
Learn more about Breast Biopsy and how tissue is evaluated after an abnormal breast finding.
Understanding Your Breast Cancer Pathology Report
After a breast biopsy confirms cancer, the tissue is examined by a pathologist to determine important characteristics of the tumor. These findings are summarized in a pathology report and help your breast care team understand what type of breast cancer is present, how the cancer cells are behaving and which treatments may be most effective.
What the Pathology Report Can Tell You
Your pathology report may identify where the cancer began, such as within the breast ducts or lobules, and whether the cancer remains confined to where it started or has invaded surrounding breast tissue. It may also describe the specific histologic type of cancer and other microscopic features seen in the biopsy sample.
The report also provides information used to guide treatment planning, including tumor grade and biomarker results such as estrogen receptor (ER), progesterone receptor (PR) and HER2 status. Additional findings may be added after surgery or further testing because a needle biopsy samples only part of the abnormal area.
Tumor Grade
Tumor grade describes how different the cancer cells and their growth pattern look compared with normal breast tissue. For invasive breast cancer, pathologists commonly use the Nottingham grading system, which evaluates three microscopic features:
- Tubule formation: How closely the cancer cells form structures resembling normal breast glands.
- Nuclear pleomorphism: How different the nuclei of the cancer cells appear in size and shape compared with normal cells.
- Mitotic count: How many cancer cells are actively dividing.
Each feature receives a score, and the combined score is used to assign the tumor a grade from 1 to 3:
- Grade 1: The cancer cells look more like normal breast cells and generally tend to grow more slowly.
- Grade 2: The cancer cells have characteristics between grades 1 and 3.
- Grade 3: The cancer cells appear more abnormal and generally tend to grow more quickly.
Grade provides useful information about how the cancer may behave, but it is only one part of the overall diagnosis. Tumor type, stage, biomarkers and other clinical findings are also considered when treatment recommendations are made.
Grade Is Not the Same as Stage
Grade and stage describe different aspects of breast cancer. Grade describes what the cancer cells look like under the microscope and gives information about how quickly they may grow. Stage describes the overall extent of the cancer, including the size and location of the tumor and whether cancer has reached nearby lymph nodes or other parts of the body.
Because staging requires information beyond the appearance of the cancer cells, your final stage may not be known from the initial biopsy alone. Imaging, surgery, lymph node evaluation and biomarker results may provide additional information that helps establish the stage.
Breast Cancer Biomarkers
Breast cancer cells are routinely tested for biomarkers that provide information about the biology of the tumor and whether certain treatments are likely to be effective. The most important routinely tested biomarkers include estrogen receptor, progesterone receptor and HER2. Other tests may be used depending on the type and stage of breast cancer.
Estrogen and Progesterone Receptors
Estrogen receptors (ER) and progesterone receptors (PR) are proteins that may be present in breast cancer cells. When a cancer is ER-positive, PR-positive or both, hormones can help stimulate the growth of the cancer. These cancers are described as hormone receptor-positive and may respond to endocrine therapy that reduces hormone activity or blocks hormones from interacting with the cancer cells.
ER and PR results are reported separately and may include the percentage of cancer cells that test positive. Your oncology team considers these results along with the other characteristics of the cancer when determining whether endocrine therapy should be part of your treatment plan.
HER2
HER2 is a protein involved in normal cell growth. Some breast cancers have increased amounts of HER2 or additional copies of the HER2 gene, which can cause the cancer cells to grow and divide more rapidly. HER2 testing helps determine whether HER2-targeted therapies may be effective.
HER2 status is commonly assessed using immunohistochemistry (IHC), which measures HER2 protein on the cancer cells. Additional testing such as in situ hybridization may be performed when the initial result requires clarification. Advances in HER2-targeted treatment have substantially expanded treatment options for patients whose cancers express HER2.
Ki-67 and Other Testing
Ki-67 is a protein found in dividing cells and may be measured to provide additional information about how actively a tumor is growing. Its usefulness varies depending on the clinical situation, and Ki-67 is interpreted together with tumor grade, hormone receptor status, HER2 and other findings rather than used by itself to determine treatment.
For selected patients, additional tumor testing may include multigene assays that evaluate the activity of groups of genes within the cancer. These tests can sometimes help estimate the likelihood of recurrence or whether chemotherapy is likely to provide additional benefit, particularly for certain early-stage, hormone receptor-positive breast cancers.
Tumor biomarker and genomic testing should not be confused with inherited genetic testing. Tumor testing examines characteristics of the cancer itself, while inherited genetic testing looks for changes passed through families that may increase the risk of developing breast and other cancers.
Learn more about Family History and Genetic Testing if your personal or family history may suggest an inherited cancer risk.
How Breast Cancer Stage Is Determined
Breast cancer stage describes the extent of the cancer and helps the care team plan treatment and discuss prognosis. Staging brings together information from the physical examination, breast imaging, pathology findings and, when appropriate, evaluation of the lymph nodes or other parts of the body.
Tumor Size and Location
The size of the invasive breast cancer and how extensively it involves the breast are important parts of staging. Imaging and pathology findings may provide this information at different points during evaluation and treatment, and the final measurement may sometimes differ from what was estimated before surgery.
Lymph Node Involvement
Breast cancer can spread to nearby lymph nodes, most commonly those in the underarm. Whether lymph nodes need to be sampled, and when that evaluation occurs, depends on the type and extent of the cancer and the treatment approach being considered.
Cancer Beyond the Breast and Nearby Lymph Nodes
Additional imaging may be recommended when the clinical findings suggest that breast cancer could involve other parts of the body. These studies are not required for every newly diagnosed breast cancer and are selected according to the stage, symptoms and other individual findings.
Tumor Biology Also Matters
Modern breast cancer staging considers more than tumor size and lymph nodes. Tumor grade and biomarker results, including estrogen receptor, progesterone receptor and HER2 status, can also help define the cancer and provide important information about its expected behavior and treatment options.
Learn more about the Types and Stages of Breast Cancer.
What Happens After Breast Cancer Is Confirmed?
Once breast cancer has been confirmed, the next step is to bring together the imaging, pathology, biomarker and staging information needed to develop a treatment plan. Not every patient follows the same sequence of care because breast cancers differ in their biology, extent and response to available treatments.
Your Breast Cancer Care Team
Breast cancer treatment often involves specialists from several disciplines, including breast surgery, medical oncology, radiation oncology, breast imaging and pathology. Plastic and reconstructive surgery, genetic counseling and other specialists may also become involved depending on the diagnosis and the patient’s individual needs.
Developing an Individualized Treatment Plan
Your treatment recommendations are based on the type of breast cancer, tumor size and location, lymph node involvement, stage, grade, hormone receptor and HER2 status, overall health and other clinical factors. Your preferences and goals are also an important part of treatment planning.
Depending on the diagnosis, treatment may include surgery, radiation therapy, endocrine therapy, chemotherapy, HER2-targeted therapy or other systemic treatments. Some patients begin with surgery, while others may receive medication before surgery to treat the cancer and evaluate how it responds.
Additional Testing When Appropriate
Some patients may benefit from additional testing before the treatment plan is finalized. This can include genomic testing of the tumor to help guide systemic therapy decisions or inherited genetic testing when the personal or family history, age at diagnosis or characteristics of the cancer suggest a possible hereditary cancer predisposition.
Explore Breast Cancer Treatment to learn more about surgery, radiation therapy and systemic treatment options.
Moving Forward With a Breast Cancer Diagnosis
A breast cancer diagnosis brings together a great deal of new information. Understanding the type of cancer, its stage, grade and biomarkers can help make the treatment plan easier to understand and give you a clearer picture of why particular therapies are being recommended.
At the Margie Petersen Breast Center, our multidisciplinary breast team reviews the clinical findings together and works with each patient to develop a treatment plan based on the characteristics of the cancer and the individual’s needs, goals and preferences.
Talk With Our Breast Clinic Team
The Breast Health Clinic can be reached at (310) 582-7209. If you have questions about a new breast symptom, need an evaluation or would like help determining your next step, call and a member of our team can assist you.
