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What is Breast Cancer?

Breast cancer starts in tissues of the breast. There are two main types of breast cancer:

  • Ductal carcinoma, the most common, starts in the tubes, or ducts, that move milk from the breast to the nipple.
  • Lobular carcinoma starts in the lobules, the parts of the breast that produce milk.

In rare cases, breast cancer can start in other areas of the breast.

Breast cancer can be invasive or noninvasive. Invasive means it has spread from the milk duct or lobule to other tissues in the breast. Noninvasive means it has not yet invaded other breast tissue.

Many breast cancers are sensitive to the estrogen hormone. This means that estrogen causes the tumor to grow. Such cancers have estrogen receptors on the surface of their cells and are considered hormone-receptor positive. About 80 percent of all breast cancers are estrogen-receptor positive (ER+), meaning the cells grow in response to estrogen.


Over the course of a lifetime, one in eight women will be diagnosed with breast cancer. Risk factors that cannot be changed include:

  • Age and gender–Your risk of developing breast cancer increases as you get older. Most advanced breast cancer cases are found in women over age 50. Men can also get breast cancer.
  • Family history of breast cancer–You may also have a higher risk of breast cancer if a close relative has had breast, uterine, ovarian or colon cancer. About 20-30 percent of women with breast cancer have a family history of the disease.
  • Genes–Some people have genetic mutations that make them more likely to develop breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect you from cancer. If a parent passes on a defective gene, you have an increased risk of breast cancer. Women with one of these defects have up to an 80 percent chance of getting breast cancer sometime during their life.
  • Menstrual cycle–Women who started menstruating early (before age 12) or went through menopause late (after age 55) have increased risks of breast cancer.

Other risk factors include:

  • Alcohol use–Drinking more than one to two glasses of alcohol a day may increase your risk of breast cancer.
  • Childbirth–Women who never had children or who had them after age 30 have an increased risk of breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces your risk of breast cancer.
  • DES–Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to some women in the 1940s–1960s.
  • Hormone replacement therapy (HRT)–You have a higher risk of breast cancer if you receive hormone replacement therapy with estrogen for several years or more.
  • Obesity–Obesity has been linked to breast cancer, although this link is not completely understood. The theory is that obese women produce more estrogen, which can fuel the development of breast cancer.
  • Radiation–If you received radiation therapy as a child or young adult to treat cancer of the chest area, you have a very high risk of developing breast cancer. The younger you started such radiation and the higher the dose, the higher your risk. This is especially true if the radiation was given during breast development.

Breast implants, use of antiperspirants and wearing underwire bras do not raise the risk of breast cancer.


Early breast cancer usually does not cause symptoms. This is why regular breast exams are important. As the cancer grows, symptoms may include:

  • Breast lump or lump in the armpit that is hard, has uneven edges and usually does not hurt
  • Change in the size, shape or feel of the breast or nipple; for example, you may have redness, dimpling or puckering that looks like the skin of an orange
  • Fluid coming from the nipple that may be bloody, clear to yellow or green, and looks like pus

Men can get breast cancer, too. Symptoms include breast lump and breast pain and tenderness.

Symptoms of advanced breast cancer may include:

  • Bone pain
  • Breast pain or discomfort
  • Skin ulcers
  • Swelling in the armpit, next to the breast with cancer
  • Weight loss

Exams and Tests

Your doctor discusses symptoms and risk factors with you before performing a physical exam. The exam includes both breasts, armpits and the neck and chest area.

Tests used to diagnose and monitor patients with breast cancer may include:

  • Breast MRI to help better identify the breast lump or evaluate an abnormal change on a mammogram
  • Breast ultrasound to show whether the lump is solid or fluid-filled
  • Breast biopsy, using methods such as needle aspiration, ultrasound-guided, stereotactic or open
  • CT scan to check if the cancer has spread
  • Mammography to screen for cancer or help identify the breast lump
  • PET scan to check if the cancer has spread
  • Sentinel lymph node biopsy to check if the cancer has spread to the lymph nodes

If your doctor learns that you do have breast cancer, more tests are performed to check if the cancer has spread. This is called staging, which helps guide future treatment and follow-up. It also gives you an idea of what to expect in the future. Breast cancer stages range from 0 to IV. The higher the staging number, the more advanced the cancer.


Treatment is based on many factors, including:

  • Type and stage of the cancer
  • Whether the cancer is sensitive to certain hormones
  • Whether the cancer overproduces a gene called HER2/neu (human epidermal growth factor receptor 2)

Cancer treatments may include:

  • Chemotherapy to kill cancer cells
  • Radiation therapy to destroy cancerous tissue
  • Surgery to remove cancerous tissue–A lumpectomy removes the breast lump; mastectomy removes all or part of the breast and possibly nearby structures as well
  • Hormone therapy to block certain hormones that fuel cancer growth
  • Biologic therapy that stimulates the body's immune system to act against cancer cells

Cancer treatment can be local or systemic:

  • Local treatments involve only the area of disease. Radiation and surgery are forms of local treatment.
  • Systemic treatments affect the entire body. Chemotherapy is a type of systemic treatment.

Most women receive a combination of treatments. For women with stage 1, 2 or 3 breast cancer, the main goal is to treat the cancer and prevent it from returning. For women with stage 4 cancer, the goal is to improve symptoms and help them live longer.

  • Stage 0–Lumpectomy plus radiation or mastectomy is the standard treatment.
  • Stage 1 and 2–Lumpectomy plus radiation or mastectomy with some sort of lymph node removal is the standard treatment. Hormone therapy, chemotherapy and biologic therapy may also be recommended after surgery.
  • Stage 3–Treatment involves surgery, possibly followed by chemotherapy, hormone therapy and biologic therapy.
  • Stage 4–Treatment may involve surgery, radiation, chemotherapy, hormone therapy or a combination of these treatments.

After treatment, some women will continue to take medicines such as tamoxifen for a time. All women will continue to have blood tests, mammograms and other tests after treatment.

Women who have had a mastectomy may have reconstructive breast surgery. This will be done either at the time of mastectomy or later.


New, improved treatments are helping people with breast cancer live longer. Even with treatment, though, breast cancer can spread to other parts of the body. Sometimes, cancer returns even after the entire tumor has been removed and nearby lymph nodes are found to be cancer-free.

How well you do after being treated for breast cancer depends on many things. Factors used to determine the risk of recurrence and the likelihood of successful treatment include:

  • Location of the tumor and how far it has spread
  • Whether the tumor is hormone receptor-positive or -negative
  • Tumor markers, such as HER2
  • Gene expression
  • Tumor size and shape
  • Rate of cell division or how quickly the tumor is growing

Possible Complications
You may experience side effects or complications from cancer treatment. For example, radiation therapy may cause temporary swelling of the breast (lymphedema) and aches and pains around the area.

Lymphedema may start six to eight weeks after surgery or after radiation treatment for cancer. It can also start slowly after cancer treatment is over. You may not notice symptoms until 18 to 24 months after treatment. Sometimes it can take years to develop.

Ask your doctor about the side effects you may have during treatment.

When to Contact a Medical Professional

Contact your healthcare provider if:

  • You have a breast or armpit lump
  • You have nipple discharge

Call your healthcare provider if you develop symptoms after being treated for breast cancer:

  • Nipple discharge
  • Rash on the breast
  • New lumps in the breast
  • Swelling in the area
  • Pain, especially chest pain, abdominal pain or bone pain


Tamoxifen is approved for breast cancer prevention in women aged 35 and older who are at high risk. Discuss this with your doctor.

Women at a high risk of breast cancer may consider preventive (prophylactic) mastectomy. This is surgery to remove the breasts before breast cancer is diagnosed. Possible candidates include:

  • Women who have already had one breast removed due to cancer
  • Women with a strong family history of breast cancer
  • Women with genes or genetic mutations that raise their risk of breast cancer (such as BRCA1 or BRCA2)

Your doctor may perform a total mastectomy to reduce your risk of breast cancer. Many risk factors, such as your genes and family history, cannot be controlled. But making healthy lifestyle changes may reduce your overall chance of developing cancer. This includes eating healthy foods:

  • Choose foods and portion sizes that promote a healthy weight
  • Choose whole grains instead of refined grain products
  • Eat more fruits and vegetables each day
  • Limit processed and red meat in the diet
  • Limit alcohol consumption to one drink per day (women at high risk of breast cancer should not drink alcohol at all)

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