Types of Breast Cancer

April 10, 2025

This page was reviewed under our medical and editorial policy by Hannah Chang, M.D., assistant professor, and Susan Yost, Ph.D., staff scientist, Department of Medical Oncology & Therapeutics Research, City of Hope^® Cancer Center Duarte

Several kinds of cancer may develop in a person’s breast tissue. Although each type has distinct traits, all are considered related diseases.

Breast cancer types are grouped, based on a number of factors, including where they start in the breast, the kind of cells they affect, their genetic (molecular) traits (including the presence or absence of certain cell proteins), how the cells look under a microscope and how the cancer cell features affect cell growth.

Women and men diagnosed with breast cancer receive a pathology report that details what type of breast cancer has been found. The doctor also explains the diagnosis and provides suggested treatment options.

Characteristics That Determine the Type

The different types of breast cancer are determined by studying characteristics of the breast tumor, including where it began, its appearance and whether it has certain hormone and genetic markers. These features help doctors pinpoint the type and develop a personalized treatment plan for each patient.

Where It Begins

Most breast cancers start in cells that line the breast structures, known as epithelial cells. These cancers are called carcinomas. Specifically, the National Cancer Institute (NCI) notes that up to 90% of breast cancer begins in the epithelial cells that line the glandular tissues. These are known as adenocarcinomas.

Breast tumors may start in:

• The lining (epithelial cells) of ducts that supply milk, which is called ductal carcinoma
• The lining (epithelial cells) of the lobules that produce breast milk, which is called lobular carcinoma

Less commonly, a malignancy begins in the breast’s connective or fat tissues or in the lining of its blood and lymph vessels. These breast cancers are called sarcomas, or lymphomas if they begin in the lymph nodes.

Appearance of Cancer Cells

A pathologist (a doctor trained to study cells) views tissue samples obtained during a breast biopsy procedure (or a tumor removed during surgery) under a microscope. After studying the tissue, the pathologist gives it a grade based on how it compares to normal (noncancerous) cells. The more abnormal the tissue looks, the higher the grade, and the faster the cancer cells are likely to grow and spread.

The pathologist also looks for certain size, shape and cell structure patterns to help determine the type or subtype of breast cancer. For example, lobular carcinoma tends to form in a single-file cell pattern.

Hormone Receptor Status

Breast tumor types are also differentiated by certain hormone receptors that are present (or absent) on the cancer cells.

Estrogen receptors: Breast cancer cells that contain estrogen receptors are called estrogen receptor positive (ER+), while those without these receptors are called estrogen receptor negative (ER-). Estrogen receptors attach to the hormone estrogen, and this hormone may help the cancer cells grow.

Progesterone receptors: Breast cancer cells that contain progesterone receptors are called progesterone receptor positive (PR+), while those without these receptors are called progesterone receptor negative (PR-). Progesterone receptors attach to the hormone progesterone, and this hormone may help the cancer cells grow.

Breast malignancies that have more estrogen and progesterone receptors tend to respond to targeted therapy that is used to block these hormones and help slow the cancer’s growth.

Genetics of Cancer Cells

Doctors also perform biomarker tests to identify certain cancer cell proteins, gene changes or gene arrangements in order to determine breast cancer type.

One of the main biomarker tests is called human epidermal growth factor receptor 2 (HER2). It checks for the HER2 protein, which helps cancer cells grow. Some breast cancers have an overabundance of HER2, and these are known as HER2-positive (HER2+) cancers. HER2+ cancer typically grows and spreads faster than HER2-negative (HER2-) cancer. HER2+ cancer tends to respond to targeted HER2 directed treatment than HER2- cancer.

Other common genetic changes (mutations) that doctors look for are changes in the BRCA1, BRCA2, PIK3CA and several other breast cancer-related genes. Understanding these changes helps the care team better evaluate how far and fast breast cancer may grow and spread, and the optimal treatments to slow or stop its metastasis.

Invasive Versus Noninvasive Breast Cancer

Another way that breast cancer is categorized into type is by identifying whether it has spread beyond the place it originated.

Invasive breast cancer: This type of cancer has grown through to surrounding tissues, organs or structures. It is sometimes called infiltrating breast cancer. Invasive breast cancers are the most common type of breast cancer and are responsible for about 83% of cases.

Noninvasive breast cancer: Noninvasive breast cancer is also called in situ. It is breast cancer that has not grown or spread beyond the place where it began. This may also be referred to as precancer because it has not infiltrated into any other tissues or structures.

Kinds of Breast Cancer

The main types of breast cancer include the following.

Ductal carcinoma in situ (DCIS): This is a noninvasive condition that is sometimes referred to as precancerous, Stage 0 breast cancer or preinvasive because the abnormal cells have not grown beyond the ducts where they first formed. About 20% of new breast cancers are DCIS. Left untreated, it has a 10% to 53% chance of progressing to invasive breast cancer. The appearance of DCIS breast tumors under a microscope varies, and includes cribriform (contains holes like mesh), micropapillary (tiny, finger-shaped growths) and solid shapes.

Lobular carcinoma in situ (LCIS): This is a relatively rare, noninvasive condition that is marked by abnormal cells located in the lining of the breast glands that produce milk (lobules). It is not technically considered breast cancer and does not usually become invasive (spreading beyond the lobules where it formed) even if left untreated — although women with LCIS have a 7 to 12 times greater risk of developing invasive breast cancer.

Lobular carcinoma cells may appear smaller than normal cells (classic), larger and more abnormal than normal cells (pleomorphic), or as a large mass with dead cells in the middle (florid).

Invasive ductal carcinoma (IDC): This is the most common type of breast cancer, accounting for about 80% of invasive cases of the disease. It metastasizes (spreads) out from the breast duct lining to surrounding tissues, structures and organs, and it may spread throughout the body via lymph nodes and blood vessels as well. If IDC appears tubular (oval, round or lobulated), cribriform or mucinous (resembling mucus) under a microscope, it tends to have an improved treatment outlook than micropapillary IDC.

Invasive lobular carcinoma (ILC): ILC spreads out from the milk-producing glands (lobules) into surrounding tissues and organs and sometimes throughout the body. It is more likely to affect both breasts (bilateral) than other invasive cancer types, with about 20% of ILC cases being bilateral. Lobular breast tumor cells typically organize into a single-file line. They are less likely to respond to chemotherapy treatment, which may be due in part to the majority of them being hormone receptor-positive (HR+) and HER2-negative (HER2-), which also reduces cancer cell response to chemotherapy. ILC accounts for about 10% of breast cancers.

Luminal A: When breast cancer cells are HER2-negative (HER2-) and hormone receptor-positive (HR+), meaning they contain estrogen and progesterone receptors, they are called Luminal A. The American Cancer Society (ACS) estimates that 68% of breast cancers fall into this category. This is a slow-growing, nonaggressive type of breast cancer with cells that look close to normal.

Luminal B: When breast cancer cells contain high amounts of a protein called Ki-67 (a sign of rapid cell division), and are also HR+, they are referred to as Luminal B. These cells are typically estrogen receptor-positive (ER+) with lower expression of progesterone receptors. Luminal B is a faster-growing, more aggressive breast cancer type than Luminal A, and it is more challenging to treat. It accounts for about 10% of breast cancers, according to ACS.

Triple-negative: This is breast cancer that is hormone receptor-negative (HR-) and HER2-. It is one of the more aggressive breast cancer types, and between 10% and 15% of cases fall into this category, according to ACS. Triple-negative cancer tends to grow quickly, recur (come back) and is usually diagnosed in more advanced stages, after it has spread.

Triple-positive: This is HER2+ breast cancer that also has estrogen and progesterone hormone receptors on the cells. It is responsive to certain therapies that target the HER2 protein and to hormone therapy that blocks estrogen and progesterone. About 10% of breast cancer cases are triple-positive, according to the NCI.

Inflammatory breast cancer (IBC): This is one type of invasive ductal carcinoma. It tends to occur in women under age 40, those who are obese and more often in Black women than white women. IBC is an aggressive (fast-growing and spreading) disease so named because the cancer cells block breast lymph nodes, making the area swell or inflame. It is marked by an orange-peel appearance on the skin. IBC accounts for between 1% and 5% of breast cancers, according to ACS. It is difficult to see on diagnostic tests and has typically advanced at least into skin tissues when diagnosed, making survival rates lower than with other forms of breast cancer.

Metastatic breast cancer: This is not a specific type of breast cancer but instead is the most advanced stage of the disease, meaning it has spread beyond the breast and nearby lymph nodes and tissues into distant organs. Its uniquely advanced characteristics impact treatment options, and doctors mainly recommend systemic (systemwide) therapies like targeted drug therapy, chemotherapy, immunotherapy and hormone therapy, since surgery would not typically allow for the complete removal of metastatic cancer. Metastatic breast cancer is sometimes called Stage 4 or distant breast cancer. The U.S. Centers for Disease Control and Prevention notes that about 6% of breast cancers were diagnosed at the distant stage between 2017 and 2021.

Recurrent breast cancer: Like metastatic breast cancer, recurrent breast cancer is not a specific type of cancer. It describes when breast cancer has returned in the same breast or elsewhere in the body after treatment had previously rendered the cancer undetectable. Breast cancer recurrence rates vary, and may be as low as 3% when treated with radiation therapy combined with breast-conserving surgery, according to the NCI.

Male breast cancer: Breast cancer is roughly 100 times less likely to occur in men than in women, and ACS projects that 2,790 cases of male breast cancer will be diagnosed in 2024. About 1 in 726 men develop the disease over a lifetime. While it is relatively uncommon, men may develop the same types of breast cancer as women, although some research shows that male breast cancer is more likely to be diagnosed at a more advanced stage.

Other Forms of Breast Cancer

Less common forms of breast cancer include the following.

Paget’s disease of the breast is breast cancer that starts in the milk ducts; spreads to the nipple where the ducts merge; is marked by a scaly, crusted, red nipple; and typically occurs alongside DCIS or IDC. It accounts for about 1% to 4% of breast cancer cases. It may be either invasive or noninvasive.

Medullary carcinoma: This invasive cancer starts in the central breast tissue; is marked by the presence of a type of white blood cell called lymphocytes; is nonaggressive (does not tend to grow and spread quickly); and occurs in less than 5% of breast cancer cases.

Tubular carcinoma: An invasive ductal carcinoma, this type of cancer is marked by tubules made of a single layer of epithelial cells; does not tend to grow and spread quickly (is low-grade or nonaggressive); and occurs in less than 5% of breast cancer cases.

Mucinous carcinoma: This is an invasive ductal carcinoma that is characterized by production of mucin (the main compound in mucous); usually occurs in postmenopausal women; and represents less than 5% of breast cancer cases.

Metaplastic breast cancer: An invasive cancer, this type of aggressive breast cancer is usually triple-negative; typically is challenging to treat compared to other types of breast cancer; and occurs in 0.2% and 5% of cases of breast cancer, according to NCI SEER data analyzed by researchers in the journal Cancers.

Phyllodes tumors: These start in breast connective tissues and have a leaf-like appearance that extends into the ducts but rarely spreads, typically occur in women in their 40s; and represent less than 1% of breast cancers, according to American Society of Clinical Oncology research.

Angiosarcoma of the breast: This is a rare breast cancer that begins in the lining of blood or lymph vessels. It typically occurs after previous radiation to the breast, tends to spread and grow quickly, and is marked by purplish skin discoloration and nodules and sometimes a lump.

Breast Cancer Care at City of Hope

The state-of-the-art Breast Cancer Program created by City of Hope encompasses convenient, advanced testing services and an array of helpful educational materials to help each patient understand their diagnosis. The program offers comprehensive, compassionate support and treatment options for each type of breast cancer, including a multitude of surgical choices and research-based advances in cancer therapy.