Breast Cancer Types and Subtypes By Jean Campbell, MS - Reviewed by a board-certified physician. Updated July 22, 2016 Most of us tend to think of breast cancer as a single disease, but research continues to prove otherwise. In addition to the different types of breast cancer, there are a number of subtypes of the disease. The type and subtype of a breast cancer, identified in a pathology report following surgery, gives a cancer care team the information they need to develop a plan that is most appropriate for successfully treating a specific type and subtype of a breast cancer. Breast Cancer TypesIf your doctor suspects breast cancer, it's worth getting to know the different types now, so you have a basis of understanding should a diagnosis prove to be a reality.Ductal Cancer: Most breast cancers begin in the ducts that carry milk, for breastfeeding, to the nipple.Ductal In-Situ (DCIS): This stage 0 cancer is located within a breast duct. It has not broken through the wall of the duct or spread into the surrounding breast tissue. Article What Is Invasive Ductal Carcinoma (IDC)? Article The 5 Types of Breast Cancer Although not life threatening at this point, DCIS needs to be treated because there is the danger of it eventually becoming an invasive cancer. DCIS is usually picked up in a routine mammogram and successfully treated with a lumpectomy (breast-conserving surgery) followed by radiation therapy.Invasive ductal carcinoma (IDC), which is also known as infiltrating ductal carcinoma, is the most common form of breast cancer. It accounts for about 80 percent of all breast cancer diagnoses. IDC initially forms within a milk duct, breaks out of the duct wall, and spreads into the surrounding breast tissue. Left untreated, IDC has the potential to spread beyond the breast and travel to distant organs. IDC may be detected during a clinical breast exam, a mammogram, an MRI, and sometimes in a breast-self exam. Treatment may include one or more standard treatments such as surgery, radiation, chemotherapy, targeted therapy, and hormone therapy.Lobular carcinoma in-situ (LCIS) describes the abnormal growth of cells in the lobules of the breast where milk is produced. While LCIS seldom progresses to an invasive cancer, lobular carcinoma in situ is considered a risk factor for developing a breast cancer in either breast. LCIS is most often found during a biopsy performed for another breast condition. Immediate treatment is not usually necessary, though following the condition closely is recommended. Women at high risk of developing a breast cancer may choose to have one or both breasts removed to lower their chances of developing the disease.Invasive lobular carcinoma (ILC), the second most common type of breast cancer, accounts for 8 percent of invasive breast cancers. Article What is Medullary Carcinoma of the Breast and How is it Treated? Article Overview of Male Breast Cancer ILC is less likely to present as a distinct lump. Treatment may include surgery, chemotherapy, radiation, and hormone therapy.Inflammatory breast cancer (IBC) is an aggressive cancer, accounting for less than 5 percent of breast cancers. It usually does not present with a lump. IBC cancer cells infiltrate the breast skin and block its lymph vessels. Symptoms may include a rash and pitted skin. The affected breast may appear red, swollen and warm to the touch. It may initially be misdiagnosed as mastitis, an infection of the breast. Depending on the stage of the cancer at diagnosis, treatment may include surgery, chemotherapy, hormone treatment, and radiation treatment.Paget’s disease of the breast accounts for less than 3 percent of breast cancers. Symptoms may include nipple discharge, possible bleeding, and itchy, scaly skin similar to eczema, a skin condition. This breast cancer is usually diagnosed through performing a nipple biopsy. About 50 percent of patients with Paget’s disease of the nipple have a tumor that can be felt in the breast during a clinical breast exam. Treatment will depend on the stage and other factors, including whether or not there is a cancerous tumor in the breast in addition to the Paget’s disease. Treatment may include surgery, chemotherapy, and hormone therapy.Rare Types of Breast Cancer IncludeThough it's less likely that you'll be diagnosed with one of these, if you're diagnosed at all, these rarer, lesser-known breast cancers are also worth being aware of.Medullary carcinoma is considered a subtype of invasive ductal carcinoma. It has a spongy feel when touched; it does not feel like a lump. It can usually be seen on a mammogram. These tumors are rarely hormone receptor positive. Treatment options include surgery, radiation, and chemotherapy.Tubular carcinoma is also considered a subtype of invasive ductal carcinoma. Its cells have a tubular appearance when looked at under a microscope. It feels spongy to the touch. It may be found during a clinical breast exam or a mammogram. Often not an aggressive cancer, it responds well to standard breast cancer treatments. Article What is Metaplastic Breast Cancer? Article What Are Common Impostors of Inflammatory Breast Cancer? Mucinous carcinoma is considered a rare form of invasive ductal carcinoma cancer, in which the cells “float” in pools of mucin, a main ingredient of mucus. A diagnosis may take several steps, including a physical exam, a mammogram, ultrasound, an MRI, and a biopsy. Treatment, depending on the stage, may include surgery, chemotherapy, radiation, and hormone therapy. Metastatic breast cancer is a stage IV breast cancer that has spread to other parts of the body, potentially including, but not limited to, the brain, bone, liver, and lungs. It is treatable, but unfortunately not curable. Less than 10 percent of those newly diagnosed with breast cancer have metastatic breast cancer when first diagnosed. Most metastatic breast cancers occur months or years after being diagnosed and treated for a localized breast cancer.Treatment is ongoing, with the goals of providing not only quality, but length of life. In addition to possibly being treated with chemotherapy, radiation, and/or hormone therapy, women and men with metastatic breast cancer may opt to see if they qualify for participation in clinical trials of new treatments.The Main Subtypes of Breast CancerDetermining the subtype of a breast cancer is done during a biopsy, conducted by a pathologist, who is a medical doctor. The pathologist confirms the presence of cancer and further examines the tumor tissue looking for genetic and hormonal characteristics of the cancerous tumor.What Are the Four Kinds of Breast Biopsies?The three main subtypes of breast cancer include: Hormone-receptor-positive: Most breast cancer patients have this subtype of breast cancer; their tumors may be stimulated to grow and spread by either estrogen or progesterone. Hormone receptor positive tumors account for 65 to 75 percent of all tumors. It is treated with drugs such as tamoxifen, which can be taken by pre- and post-menopausal women, or aromatase inhibitors that can only be taken by patients who are post menopausal. The hormonal therapies block the activity of estrogen to reduce the chance of having a breast cancer recurrence.HER2-positive: These tumors have the human epidermal growth factor 2, which is a gene that transmits the HER receptor protein. While this receptor is necessary in the normal growth of breast cells, in excess, the HER2 receptor may result in a cancer growing. Chemotherapy is the usual treatment.Triple-negative: A triple-negative breast cancer does not have estrogen receptors, progesterone receptors, or HER2 receptors. Triple-negative tends to be more aggressive and affects almost 15 percent of those with breast cancer. Because triple-negative doesn’t have hormone and HER2 receptors, it doesn’t respond to hormone therapy, and chemotherapy is the recommended treatment.A Word From VerywellWhatever the type or subtype of a breast cancer, it is always best found and treated at the earliest possible stage, before it has spread and when it has the most favorable outcome. See your family physician or gynecologist for an annual checkup that includes a comprehensive breast exam. Learn about your family history of breast cancer; if there is breast cancer in your family, have a conversation with your care provider about when you need to begin having mammograms.If there is no family history of breast cancer, remember that 85 percent of breast cancers occur in women with no family history of the disease. Don’t put off getting routine mammograms starting at age 40.I’m glad I did. Twice, mammograms found a cancer in my breast before it could be felt in a clinical breast exam, and before either breast cancer needed to be treated with chemotherapy.Sources:American Cancer Society. Types of Breast Cancer. Last Medical Review: 09/25/2014Last Revised: 05/04/2016.Cancer.Net. Breast Cancer-Treatment Options. Approved by the Cancer.Net Editorial Board, 02/2016.