What are Different Types of Breast Cancer? Plus Treatment Options

Similar to many cancers today, breast cancer is not a single disease.

“Each year we learn more about molecular subtypes of breast cancer that may impact on treatment and prognosis, but the basics have remained the same for many years,” said Dr. Grace Makari-Judson, Co-Director of the Rays of Hope Center for Breast Cancer Research.

Breast cancer is known to have existed at least 3,500 years ago in ancient Greece and Egypt based on knowledge from the Edwin Smith Surgical Papyrus, dating back to 3,000–2,500 B.C., which provides authentic accounts of breast cancer referring to “bulging tumors of the breast that has no cure.” The only “so-called” medicine at the time was a votive offering that the ancient Greeks made to the god of medicine.

Jumping ahead thousands of years, modern-day treatments have now resulted in saving the lives of many people with breast cancer compared to ancient times. According to the American Cancer Society, there are more than 4 million breast cancer survivors – including those still being treated and those who have finished their treatment – in the United States. And there is more good news. While slowing slightly in recent years, breast cancer death rates have been decreasing since 1989 for an overall decline of 43% through 2020. Thanks, in part, to screening methods and to new innovative treatments.

Breast cancer can be separated into two main categories – invasive, where cancer has escaped from the ducts and has the potential to spread, and non-invasive, which does not go beyond the milk ducts or lobules in the breast. Invasive breast cancer accounts for nearly 80% of all breast cancers, while about 20% are non-invasive.

Invasive Breast Cancer

Invasive breast cancer is when abnormal cells that begin in the breast ducts or lobules of the breast then invade the surrounding breast tissue, and may involve lymph nodes and potentially spread to distant organs. Women have a 1 in 8 chance of developing invasive breast cancer during their lifetime. Men have a 1 in 800-1000 chance.

The most common forms of invasive breast cancer are invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC). When cancer cells leave the breast and spread to distant organs such as the liver or lungs, the cancer is considered metastatic.

Most often discovered first on a mammogram, common symptoms of invasive breast cancer may include:

• Changes in breast shape or size
• Discharge from the nipple that is not breastmilk
• Swelling of the breast and other skin changes such as redness or dimpling
• A lump in the breast tissue
• Thickening of the nipple skin

Invasive ductal carcinoma (IDC)

IDC, also referred to as infiltrating ductal carcinoma, accounts for about 80% of all breast cancer diagnoses. It starts in the cells that line the milk ducts and from there the cancer cells invade breast tissue beyond the walls of the duct, possibly spreading (metastasizing) to other parts of the body through the lymph system and bloodstream.

Invasive lobular carcinoma (ILC)

The second most common form of breast cancer diagnosed in the United States, constituting about 10% of all breast cancers, begins in the glands in the breast that produce milk called lobules. More likely to affect both breasts compared to other invasive carcinomas, similar to IDC it can spread to other parts of the body.

Rare Invasive Breast Cancers

Among the rare types of invasive breast cancer are:

• Medullary – A rare form of breast cancer that has a better prognosis than conventional breast carcinoma, medullary breast cancer accounts for less than 5% of all invasive breast cancers.
• Mucinous – An uncommon breast cancer that is less aggressive than other invasive ductal cancers, it accounts for about 2% of all breast carcinomas.
• Tubular – Accounting for 1-2% of invasive breast cancers, tubular breast cancer is rare with a very favorable prognosis.
• Metaplastic – A rare and aggressive type of invasive breast cancer that accounts for less than 1% of breast tumors, metaplastic breast cancer is fast growing and can spread.
• Papillary – Papillary breast cancer is a very rare form of invasive breast cancer that represents approximately 0.5% of invasive breast cancers.
• Micropapillary – A rare variant of invasive ductal carcinoma accounting for less than 5% of all breast cancer cases, it is more aggressive with a poor prognosis and high early recurrence rate.
• Apocrine - Apocrine breast cancer is a rare and unique type of invasive ductal breast cancer that accounts for 1-4% of all breast malignancies.

Within the types of breast cancer, disease is further classified by subtypes based on hormone receptors (estrogen receptor ER and progesterone receptor PR) and human epidermal growth factor receptor 2, also known as HER2. ER positive and PR positive are considered hormone receptor positive. HER2-positive cancers, which previously were felt to be fast growing and aggressive, respond extremely well to HER2-directed treatments and prognosis has dramatically improved. When ER, PR and HER2 are all negative, the cancer is referred to as triple negative. These subtypes are critical in determining the best medical treatment.

Non-Invasive Breast Cancer

Non-invasive breast cancer is when cancer cells are found in the lobules or milk ducts of the breast, but have not invaded other tissue or organs beyond the breast. It accounts for about 20% of all breast cancers and can include ductal carcinoma in situ (DCIS), or the rare Paget’s disease. Lobular neoplasia (LCIS) is sometimes included in this category but is not cancer. All DCIS cancers are considered as stage 0 (breast cancer stages 0, 1, 2, 3 or 4 identify how widespread the cancer is in the breast tissue to other parts of the body - the higher the number, the more the cancer has spread) which is the earliest stage possible, and are highly treatable. A more complete look at staging can be found on the American College of Surgeons website.

“Patients with non-invasive breast cancer do not die from the disease,” Dr. Makari-Judson said.

While in most cases there are no symptoms to recognize non-invasive breast cancer other than the results of a mammogram, some signs might include:

• Breast lump
• Nipple discharge

Ductal carcinoma in situ (DCIS)

DCIS occurs when a tumor is found in the milk ducts, but has not spread beyond them, treatment is advised since it may become invasive over time.

Lobular neoplasia

Lobular neoplasia is a condition when abnormal cells are discovered in the lobules of the breast. It is not considered cancer, but increases the risk of developing breast cancer.

Paget’s disease of the breast

A rare type of breast cancer involving the skin of the nipple and extending to the dark circle of skin around the nipple called the areola, it accounts for approximately 1-4% of all breast cancers. It can be invasive if it has a lump or non-invasive if there is no lump. Prognosis is excellent if it hasn’t spread beyond the milk ducts.

Treatment for Breast Cancer

Treatment for invasive breast cancer is based on the stage of cancer and biologic subtype, including hormone receptors and HER2 status. Treatment for early-stage breast cancer may include surgery, radiation, hormonal treatments, chemotherapy, immunotherapy and/or HER2-directed monoclonal antibodies.

Surgery

Options for breast cancer surgery include a mastectomy, which removes the whole breast, or a lumpectomy to remove the cancer and some normal tissue around it, but not the entire breast. It includes evaluation of lymph nodes under the arm. Survival following breast-conserving surgery is similar to mastectomy.

Radiation therapy

Radiation therapy uses high-energy rays similar to X-rays to kill the cancer cells to treat the breast, chest wall and regional lymph nodes.

“For early-stage breast cancer, there are local treatments that just treat the breast area such as surgery and radiation, and systemic treatments that travel throughout the body in case cancer cells have escaped. The idea is to be able to kill these cancer cells before they set up shop somewhere else in the body,” Dr. Makari-Judson said.

Systemic treatment for early-stage breast cancer is personalized based on the hormone receptor status and HER2 and may include the following:

• Chemotherapy - Chemotherapy involves special medicines to kill rapidly dividing cancer cells. The drugs can be pills or medicines given intravenously, sometimes both. It is used in triple negative cancers, HER2-positive in combination with HER2 treatments and for some hormone receptor positive cancers.
• Hormonal therapy – Usually administered as pills that block cancer cells from getting the hormones they need to grow, hormonal therapy is used in ER and PR positive cancers.
• Immunotherapy - Immunotherapy works with your body’s immune system to help it fight cancer cells or to control side effects from other cancer treatments. It is used in some triple negative cancers with chemotherapy
• HER2-directed monoclonal antibodies - These medications are specifically targeted to those cancers that have too much HER2, such as HER2-positive, and are used in combination with chemotherapy.
• Targeted therapy drugs - Targeted therapy involves treatments that target the cancer’s specific genes, proteins, or the tissue environment that contributes to cancer growth and survival.

“We treat patients with DCIS, which is non-invasive, similar in some ways to invasive cancer, meaning we may recommend surgery, radiation and hormonal treatments. This is because we are trying to prevent the cancer from recurring. If DCIS recurs, which is about half of the time, it may come back as an invasive cancer,” Dr. Makari-Judson said.

“For patients with metastatic breast cancer, there are over 30 new treatments that have been introduced since the 1990s. This includes new categories of medications targeted to specific molecular abnormalities in the cancer cells sometimes referred to as precision medicine. Although not curable, metastatic breast cancer may be highly treatable with options that allow for good quality of life,” she added.

The optimal treatment for breast cancer today involves a multidisciplinary team like that found at Baystate Health. The team includes surgeons, medical oncologists, radiation oncologists, pathologists, and radiologists, who work together to provide the most appropriate care for each individual patient.

Dr. Makari-Judson noted a diagnosis of breast cancer is often “overwhelming” for patients.

But no one has to face it alone.

“A diagnosis of breast cancer is both life-changing and overwhelming as you deal with the stress of learning that you have cancer. Breast cancer specialists at Baystate Health are there every step of the way to guide you with their expertise and to personalize and optimize treatment on your breast cancer journey,” Dr. Makari-Judson said.

“The good news is that since the first Rays of Hope - A Walk and Run Toward the Cure of Breast Cancer in 1994, we have made tremendous strides,” she added.