Breast Cancer

What is breast cancer?

The breast is made of fatty tissue, ducts and lobules. The lobules make breast milk. The ducts are thin tubes that carry it to the nipple. The ducts and the lobules are the two parts of the breast where cancer is most likely to start.

Breast cancer is one of the most common types of cancer in the U.S. Once breast cancer forms, cancer cells can spread to other parts of the body (metastasize), making it life-threatening.

Breast cancer can be invasive or noninvasive. Invasive breast cancer spreads through the blood vessels and lymph vessels. Noninvasive breast cancer stays within the ducts and lobules of the breasts.

When cancer cells spread, nearby lymph nodes may be affected, such as in the armpit. These lymph nodes are called axillary lymph nodes. They are often checked for cancer as part of the diagnosis process. If the cancer reaches these nodes, it may have spread to other parts of the body.

Breast cancer that has spread from the breast to other organs of the body is called metastatic breast cancer. When breast cancer spreads, it most often goes to the brain, bones, liver or lungs.


What are the types of breast cancer?

There are many types of breast cancer. These are the most common types:

  • Ductal carcinoma: This is the most common type. It starts in the lining of the milk ducts. When breast cancer has not spread outside of the ducts, it's called ductal carcinoma in situ or intraductal carcinoma. This is the most common type of noninvasive breast cancer. Invasive ductal carcinoma is breast cancer that has spread beyond the walls of the breast ducts. It's the most common type of invasive breast cancer.
  • Invasive lobular carcinoma: This type starts in the milk-producing glands (lobules) and spreads outside the lobules.
  • Inflammatory breast cancer: This is a rare form of invasive breast cancer. Often there is no lump or tumor. Instead, this cancer makes the skin of the breast look red and feel warm. The breast skin also looks thick and pitted, like an orange peel. It tends to be found in younger people and grows and spreads quickly.
  • Triple negative breast cancer: This is a type of breast cancer that doesn’t have estrogen receptors and progesterone receptors. It also doesn’t have an excess of the HER2 protein on the cancer cell surfaces. This type of breast cancer is most often found in younger people and in Black people. It tends to grow and spread faster than most other types of breast cancer. Because these cancer cells don't have hormone receptors or excess HER2, medicines that target these changes don't work. The most common kind is triple-negative invasive ductal carcinoma.
  • Paget disease: This is a very rare form of breast cancer that starts in the glands in the skin of the nipple. It grows slowly and occurs in only one nipple. Most people with Paget disease also have tumors in the same breast. This type causes symptoms that are like a skin infection. They include inflammation, redness, oozing, crusting, itching and burning.
  • Angiosarcoma: This starts in the cells that line the blood vessels or lymph vessels. It may involve the breast tissue or the breast skin.


It’s best to catch breast cancer early, which means being aware of the signs and symptoms of breast cancer.

  • A lump, thickening or swelling in or near your breast or under your arm
  • A change in the size or shape of your breast
  • Nipple discharge that's often bloody and only in one breast
  • Nipple inversion, meaning the nipple pulls back into your breast
  • Nipple or breast pain, tenderness or aching
  • A change in the look of the skin of your breast, areola or nipple, such as becoming dimpled or puckered or turning red or purple
  • A change in the feel of the skin of your breast, areola or nipple, such as turning itchy or scaly

Risk Factors

What causes breast cancer?

The exact cause of someone’s cancer may not be known. There are risk factors that can make it more likely for a person to develop cancer. Some risk factors may not be in your control. But others may be things you can change.

The risk factors for breast cancer include:

  • Certain breast changes that are not cancer
  • Certain gene changes passed in families
  • Drinking alcohol
  • First pregnancy at a late age
  • Having many family members with breast, ovary, uterus, colon or prostate cancer
  • History of breast cancer
  • Never having children or never breastfeeding
  • Not being physically active
  • Obesity
  • Older age
  • Radiation treatment to your chest when you were young
  • Smoking tobacco
  • Starting your period when you’re young or stopping at a late age
  • Using certain hormone therapies for menopause changes


How to prevent breast cancer

The best form of preventing breast cancer is living a healthy lifestyle. Eating a well-balanced diet, keeping active, avoiding cancer-causing behaviors like drinking alcohol and smoking tobacco and getting provider-recommended vaccinations.

Another important step to prevent cancer is to take all the steps to catch any precancerous or cancerous cells early. There are three steps that should be regularly taken to prevent and catch breast cancer:

Step 1: Breast Self-Examination (BSE)

The American Cancer Society (ACS) says that breast self-exams are an option for women ages 20 and older as a means of familiarizing themselves with their breasts so they can notice changes more easily. BSE should be done regularly at the same time every month.

Step 2: Clinical Examination

A breast examination by a physician or nurse trained to evaluate breast problems should be part of a woman's physical examination. The ACS recommends:

  • Between ages 20 and 39, women should have a clinical breast examination (CBE) by a health professional every three years.
  • After age 40, women should have a breast examination by a health professional every year.

Step 3: Mammography

Mammography is a low-dose X-ray of the breasts. It's the most common imaging technique. Mammography can detect cancer or other problems before a lump becomes large enough to be felt, as well as assist in the diagnosis of other breast problems. However, a biopsy is required to confirm the presence of cancer.

The ACS recommends yearly screening for all women ages 40 and older. Women should talk with their provider about their personal risk factors before making a decision about when to start getting mammograms and how often they should get them.

A diagnostic mammogram may be required when a questionable area is found during a screening mammogram.


How is breast cancer diagnosed?

The most common way to find breast cancer is during a routine mammogram before you have symptoms or if you find a lump in your breast or armpit. If you find a lump, you should see a health care provider right away. The health care provider will look at your breasts and feel the lump. Ultrasound may be used to see if the lump is solid or filled with fluid. A mammogram of the breast is often done.

A biopsy is the only way to know if a lump or change is cancer. Small pieces of tissue are taken out and checked for cancer cells. A hollow needle may be used to take out the bits of tissue. The samples are sent to a lab. Your results will come back in about one week.

After a diagnosis of breast cancer, you may have other tests. They can help determine the stage of the cancer.

What are the stages of breast cancer?

A prognostic stage group can have a value of 0 to 4. The higher the number, the bigger the cancer is or the more it has spread beyond the breast, or both.

Can men get breast cancer?

Breast cancer can start in both women and men. Both women and men have breast tissue, and those cells can turn into cancer. However, breast cancer is very rare in men.

The most common type of breast cancer in men is infiltrating ductal cancer. This starts in cells lining the milk ducts and spreads to nearby tissues.

Other far less common types of breast cancer in men include ductal carcinoma in situ (DCIS), inflammatory breast cancer and Paget disease of the nipple. A type of breast cancer called lobular carcinoma in situ is very rare in men. This is because men don't have much lobular tissue. (Lobular tissue is where breast milk is made.)

Experts think that genes may play a role in breast cancer development in men. These include a family history of breast cancer in a first-degree relative and inherited mutations of the BRCA genes. Genes other than BRCA may also play a role. But each cancer case is different.


How is breast cancer treated?

Addressing early signs of breast cancer is one of the most important things to successfully treating cancer. Your breast cancer treatment choices depend on the type of breast cancer you have, test results and the stage of the cancer. Other things to think about are if the cancer can be removed with surgery and your overall health. The goal of treatment may be to cure you, control the cancer or help ease problems caused by the cancer.

Types of treatment for cancer are either local or systemic. Local treatments remove, destroy or control cancer cells in one area. Surgery and radiation are local treatments. Systemic treatment is used to destroy or control cancer cells that may have spread in your body. When taken by pill or injection, chemotherapy is a systemic treatment.

The most common forms of treatment include:

  • Surgery. Surgery is done to remove the tumor from your breast. Surgery is the most common way to treat breast cancer. In some cases, only the tumor is removed, and the rest of the breast is left intact. In other cases, the entire breast is removed. Your surgeon may also use surgery to see if the cancer has spread to the lymph nodes under your arm. Knowing if the cancer has spread can help you and your healthcare team make decisions about other types of treatment you may need after surgery. After a breast is removed, surgery may be used to reconstruct a breast. This can be done with either your own tissue or an implant.
  • Radiation therapy. This type of therapy uses high-energy X-rays to kill cancer cells. This treatment can be used to shrink a tumor before surgery. Or it may be used after surgery to kill cancer cells that may remain in the breast or chest area. Radiation may also be used to treat tumors in other areas of the body.
  • Chemotherapy. This treatment uses powerful medicines to kill cancer cells all through the body. It may be used to shrink a tumor before surgery. Or it may be used to kill any cancer cells that remain after local treatments. It's often used along with hormone therapy. Chemotherapy may also treat tumors that have grown in other places in the body. Breast cancer that has spread is usually treated with chemotherapy.
  • Hormone therapy. This treatment stops the growth of cancer cells that rely on certain hormones. It can be delivered in two ways. One way to get hormone therapy is with medicines, such as tamoxifen. Another way is by removing the ovaries, which make hormones. Hormone therapy may be used after surgery to decrease the chance of breast cancer coming back, or a new cancer growing. It can also be used to treat cancer that has spread. It’s sometimes used with chemotherapy.
  • Targeted therapy. This treatment uses medicines that target the changes in a cancer cell that make a tumor grow and spread. These medicines either destroy or slow the growth of cancer cells. The medicines tend to have fewer side effects that are less severe. The medicine trastuzumab may be used for some types of breast cancer. It targets the protein HER-2.
  • Immunotherapy. This treatment uses the body’s own immune system to help it recognize and attack cancer cells. Some types of breast cancer can be treated with immunotherapy. The medicine atezolizumab may be used in the treatment of advanced triple-negative breast cancer.

What are common breast cancer treatment side effects?

Cancer treatment, such as chemotherapy and radiation, can damage normal cells. This causes side effects, such as hair loss, mouth sores and vomiting. There may be things you can do and medicines you can take to help prevent or control side effects.

What is the breast cancer survival rate?

The five-year survival rate of breast cancer depends on when treatment starts and at what stage the cancer is.

  • Stage 1: The five-year survival rate is 98-100%
  • Stage 2: The five-year survival rate is 90-99%
  • Stage 3: The five-year survival rate is 66-98%


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