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The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on April 9, 2021.

Common breast cancer types

After skin cancer, breast cancer is the most common type of cancer diagnosed in women. About 284,200 cases will be diagnosed in 2021, according to the American Cancer Society (ACS). Men also may develop breast cancer, though it’s much more rare.

Breast cancer is classified into different types based on how the cells look under a microscope. Most breast cancers are carcinomas, a type of cancer that begins in the linings of most organs.

Ductal carcinoma in situ (DCIS)

DCIS is the most common type of noninvasive breast cancer, with about 60,000 new cases diagnosed in the United States each year. About one in every five new breast cancer cases is ductal carcinoma in situ.

Also called intraductal carcinoma or stage 0 breast cancer, it’s considered a noninvasive breast cancer. With DCIS, abnormal and cancerous cells haven’t spread from the ducts into nearby breast tissue nor anywhere else, such as the lymph nodes.

DCIS is divided into several subtypes, mainly according to the appearance of the tumor. These subtypes include micropapillary, papillary, solid, cribriform and comedo.

Patients with ductal carcinoma in situ are typically at higher risk for seeing their cancer return after treatment, although the chance of a recurrence is less than 30 percent. Most recurrences occur within five to 10 years after the initial diagnosis and may be invasive or noninvasive. DCIS also carries a heightened risk for developing a new breast cancer in the other breast. A recurrence of ductal carcinoma in situ would require additional treatment.

The type of therapy selected may affect the likelihood of recurrence. Treating DCIS with a lumpectomy (breast-conserving surgery), and without radiation therapy, carries a 25 percent to 35 percent chance of recurrence. Adding radiation therapy to the treatment decreases this risk to about 15 percent. Currently, the long-term survival rate for women with ductal carcinoma in situ is nearly 100 percent.

Invasive ductal carcinoma (IDC)

Sometimes, ductal carcinoma can become an invasive cancer. With invasive ductal carcinoma, cancer spreads from a milk duct, where it originates, into nearby tissue and lymph nodes. From there, it may spread, or metastasize, to other parts of the body, such as the bones and distant organs. Cancerous cells travel and spread through the lymph system (which is part of the immune system) or bloodstream.

About eight in 10 invasive breast cancers are invasive ductal carcinoma, according to the ACS.

Surgery typically is the first treatment for IDC. The goal of this treatment is to remove the cancer from the breast with a lumpectomy or mastectomy. The type of surgery recommended depends on factors such as the tumor’s location and size and whether more than one area in the breast has been affected. For patients with ductal carcinoma, long-term systemic treatment with tamoxifen is recommended to prevent recurrence.

Below are four types of invasive ductal carcinoma that are less common:

Medullary ductal carcinoma: This type of cancer is rare and accounts for 3 percent to 5 percent of breast cancers. It is called “medullary” because, under a microscope, it resembles part of the brain called the medulla. Medullary carcinoma may occur at any age, but it typically affects women in their late 40s and early 50s. Medullary carcinoma is more common in women who have a BRCA1 gene mutation. Medullary tumors are often “triple-negative,” which means they test negative for estrogen and progesterone receptors and for the HER2 protein. Medullary tumors are less likely to involve the lymph nodes, are more responsive to treatment, and may have a better prognosis than more common types of invasive ductal cancer.

Surgery is typically the first-line treatment for medullary ductal carcinoma. A lumpectomy or mastectomy may be performed, depending on the location of the tumor. Chemotherapy and radiation therapy may also be used.

Mucinous ductal carcinoma: This type of breast cancer accounts for less than 2 percent of breast cancers. Microscopic evaluations reveal that these cancer cells are surrounded by mucus. Like other types of invasive ductal cancer, mucinous ductal carcinoma begins in the milk duct of the breast before spreading to the tissues around the duct. Sometimes called colloid carcinoma, this cancer tends to affect women who have gone through menopause. Mucinous cells are typically positive for estrogen and/or progesterone receptors and negative for the HER2 receptor.

Surgery is typically recommended to treat mucinous ductal carcinoma. A lumpectomy or mastectomy may be performed, depending on the size and location of the tumor. Adjuvant therapy, such as radiation therapy, hormonal therapy and chemotherapy, may also be required. Because most mucinous carcinomas test negative for receptors for the protein HER2, they aren’t typically treated with trastuzumab (Herceptin®).

Papillary ductal carcinoma: This cancer is also rare, accounting for less than 1 percent of invasive breast cancers. In most cases, these types of tumors are diagnosed in older, postmenopausal women. Under a microscope, these cells resemble tiny fingers or papules. Papillary breast cancers are typically small, and test positive for the estrogen and/or progesterone receptors and negative for the HER2 receptor. Most papillary carcinomas are invasive and are treated like invasive ductal carcinoma.

Surgery is typically the first-line treatment for papillary breast cancer. A lumpectomy or mastectomy may be performed, depending on the size and location of the tumor. After surgery, adjuvant therapy may be required, including radiation, chemotherapy and/or hormone therapy.

Tubular ductal carcinoma: Another rare type of IDC, this cancer makes up less than 2 percent of breast cancer diagnoses. Like other types of invasive ductal cancer, tubular breast cancer originates in the milk duct, then spreads to tissues around the duct. Tubular ductal carcinoma cells form tube-shaped structures. Tubular ductal carcinoma is more common in women older than 50. Tubular breast cancers typically test positive for the estrogen and/or progesterone receptors and negative for the HER2 receptor.

Treatment options for tubular ductal carcinoma depend on the aggressiveness of the cancer and its stage. Treatment often consists of surgery, which includes a lumpectomy or mastectomy, and additional (adjuvant) therapy, which may include chemotherapy, radiation and/or hormone therapy.

Lobular carcinoma

Lobular carcinoma begins in the lobes or lobules (glands that make breast milk). The lobules are connected to the ducts, which carry breast milk to the nipple.

Lobular carcinoma in situ (LCIS): It begins in the lobules and doesn’t typically spread through the wall of the lobules to the surrounding breast tissue or other parts of the body. While these abnormal cells seldom become invasive cancer, their presence indicates an increased risk of developing breast cancer later. About 25 percent of women with LCIS will develop breast cancer at some point in their lifetime. This subsequent breast cancer may occur in either breast and may appear in the lobules or in the ducts.

Because LCIS isn’t actually cancer, treatment may not be recommended. If you’re diagnosed with lobular carcinoma, you may want to ask your doctor about more frequent breast cancer screenings. Increasing surveillance may help ensure that any subsequent breast cancer is detected in its earliest, most treatable stages.

Invasive lobular carcinoma (ILC): Among the invasive breast cancers, about 10 percent are invasive lobular carcinomas, or ILC. This cancer starts in the breast’s milk-producing glands, which are called lobules, and may spread to other parts of the body. About 20 percent of women with ILC have cancer in both breasts, according to the ACS.

The treatment options for invasive lobular carcinoma include localized approaches such as surgery and radiation therapy that treat the tumor and the surrounding areas, as well as systemic treatments such as chemotherapy and hormonal or targeted therapies that travel throughout the body to destroy cancer cells that may have spread from the original tumor.