Breast cancer subtypes
Breasts are made up of two main types of cells; the breast lobules, which make milk, and the breast ducts which carry the milk to the nipple. The most common type of breast cancer - known as "ductal carcinoma" starts in the ducts. Less common is "lobular carcinoma," which starts in the breast lobules.
There are other, very rare types of breast cancer. Inflammatory breast cancer is a very fast growing type of ductal carcinoma. Paget's disease of the breast is a type of ductal carcinoma that affects the nipple and areola. Phyllodes tumors start in the connective tissue of the breast.
Stages of breast cancer
The stage of a cancer refers to whether the cancer has spread beyond the breast, and if so, where in the body the cancer has spread. Measuring the stage of breast cancer helps doctors decide how to treat it. Breast cancer most often starts as a lump within the breast that can grow and spread:
- within the breast
- to nearby tissue (such as lymph nodes, skin or the chest wall)
- through the blood stream or lymph system to distant organs (metastasis)
In breast cancer, there are five major stages.
- Stage 0: A stage 0 breast cancer is known as a ductal carcinoma in situ (DCIS), a non-invasive form of the disease. The tumor cells are contained within the ducts of the breasts, and have not invaded beyond the duct. Cancers caught and treated at stage 0 are very unlikely to recur or spread.
- Stage 1: A small tumor (< 2 cm) that is contained within the breast and has not spread to the lymph nodes.
- Stage 2: A stage 2 breast cancer can be either a larger tumor that involves the breast only, or a tumor that has spread to some lymph nodes in the armpit.
- Stage 3: A stage 3 breast cancer can be either a tumor in the breast that invades the skin or chest muscle, or a tumor that involve several lymph nodes surrounding the breast (in the armpit, near the collarbone, near the breast bone). Stage 3 breast cancers are sometimes called “locally advanced.”
- Stage 4 or metastatic: A stage 4 breast cancer is one that has spread beyond the breast and the regional lymph nodes to another place in the body, such as the bone, lung, and/or liver. Stage IV breast cancers are also called “advanced” or “metastatic.”
Generally, breast cancers diagnosed at stages 1-3 are considered curable, so treatment plans are made with the goal of cure. Metastatic breast cancer is often treatable at diagnosis. Over time, metastatic breast cancer is likely to progress or recur; sometimes after several different types of treatment. There are many different treatments available for metastatic breast cancer, and clinical trials testing new treatments are often available.
Subtypes and biomarkers
After a biopsy or surgery confirms breast cancer, pathologists look closely at the cells for additional clues on how to best treat the cancer. All breast cancers are tested for common changes, called tumor biomarkers: estrogen receptor (ER), progesterone receptor (PR), and HER2. The results of these tumor biomarker tests play a major role in choice of cancer treatment:
- ER-positive and PR-positive breast cancers: Breast cancers with these biomarkers are often called "hormone sensitive" breast cancers. These are usually treated with hormone therapy. Chemotherapy may also be recommended depending on the stage of the tumor and other factors. A targeted therapy known as a CDK4/6 inhibitor (Ibrance) has been FDA approved for treating metastatic or advanced hormone receptor positive, Her2-negative breast cancer in combination with an aromatase inhibitor.
- HER2-positive breast cancers: these cancers benefit from therapies that target the Her2 molecule. Therapies include Herceptin (trastuzumab) and Perjeta (pertuzumab). Anti-HER2 therapy is given with chemotherapy in patients with early-stage, curable tumors. Patients whose tumors are HER2-positive and ER-positive receive hormone therapy, as well as chemotherapy and anti-HER2 therapy.
- ER-negative and PR-negative breast cancers: these are almost always are treated with chemotherapy because hormone therapy does not benefit patients with these types of tumors.
- Triple-negative breast cancers: tumors that are negative for all three markers are referred to as triple-negative breast cancer or sometimes "TNBC" for short. Like other ER-negative breast cancers, triple-negative breast cancers are almost always treated with chemotherapy. People with BRCA1 mutations are more likely to develop triple-negative breast cancer than any other type of breast cancer.
Additional tests can be performed on tumor samples to help guide treatment. Prognostic genomic tests can also help guide treatment decisions. For some patients with advanced cancers, tumor testing can look for additional tumor markers to help guide the choice of targeted therapies. At the moment, this type of tumor testing for targeted therapy is mostly experimental and used within research studies.
Some types of breast cancer are more common in people with inherited mutations linked to cancer.
- The National Accreditation Program for Breast Centers (NAPBC) certifies centers that commit to providing the best possible breast care.
- National Cancer Institute-Designated Cancer Centers deliver cutting-edge cancer treatments to patients in communities across the United States.
- The National Comprehensive Cancer Network (NCCN) maintains a list of comprehensive cancer centers.
If you are a person who has been diagnosed with breast cancer, you can find peer support through the following resources:
- Register for the FORCE Message Boards to connect with others who share your situation. Once you register, you can post on the Share Your Mutation board to connect with other people who carry an inherited mutation and the Diagnosed With Cancer board to connect with other people who have been diagnosed with breast cancer.
- FORCE's Peer Navigation Program will match you with a volunteer who shares your mutation and situation and provide you with a free resource guide.
- Contact the FORCE impact leaders in your area to link to local support groups and other resources.
- Attend a virtual support meeting in your area.
- Read the stories from members of our community.
Other organizations that provide support for people diagnosed with breast cancer include:
- HIS Breast Cancer Awareness is an organization providing information and awareness for men with breast cancer.
- Living Beyond Breast Cancer is a national organization for people diagnosed with breast cancer across the care continuum.
- METAvivor is a national nonprofit organization that provides support for women with metastatic breast cancer and that funds metastatic cancer research.
- SHARE is a nonprofit that provides support and information for women with breast, ovarian or endometrial cancer.
- Sharsheret is a national organization for the Jewish breast and ovarian cancer community.
- Young Survival Coalition is an organization for young people diagnosed with breast cancer.