What is breast cancer

Breast cancer is cancer that starts in the tissues of the breast. Most breast cancers start in the tubes that move milk from the breast to the nipple and are known as ductal carcinoma. Less commonly cancer starts in the parts of the breast that produce milk (lobular carcinoma). In rare cases, breast cancer can start in other areas of the breast.

Breast cancer can be invasive, meaning it’s spread from the milk duct or lobule to other tissues in the breast, or noninvasive, meaning it hasn’t yet invaded other breast tissue. Noninvasive breast cancer is called “in situ.”

Ductal carcinoma in situ (DCIS), or intraductal carcinoma, is breast cancer in the lining of the milk ducts that has not yet invaded nearby tissues. It may progress to invasive cancer if untreated. Lobular carcinoma in situ (LCIS) is a marker for an increased risk of invasive cancer in the same or both breasts.

Many breast cancers are sensitive to the hormone estrogen, meaning that estrogen causes the breast cancer tumor to grow. These cancers have estrogen receptors on the surface of their cells called estrogen receptor-positive cancer or ER-positive cancer.

Some women have HER2-positive breast cancer. HER2 refers to a gene that helps cells grow, divide, and repair themselves. When cells (including cancer cells) have too many copies of this gene, they grow faster. In the past, women with HER2-positive breast cancer had a more aggressive disease and a higher risk of the cancer returning than women who didn’y have this type, but this is changing with specifically targeted treatments against HER2.


Over the course of a lifetime, 1 in 8 women will be diagnosed with breast cancer.

Risk factors you cannot change:

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, but are 100 times less likely than women to do so.

Family history of breast cancer

You may also have a higher risk of breast cancer if you have a close relative who had breast, uterine, ovarian, or colon cancer. About 20 – 30% of women with breast cancer have a family history of the disease.


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 you a defective gene, you have an increased risk of breast cancer. Women with one of these defects have up to an 80% chance of getting breast cancer sometime during their life.

Menstrual cycle

Women who got their periods early (before age 12) or went through menopause late (after age 55) have an increased risk of breast cancer.

Other risk factors include:

Alcohol use

Drinking more than 1 – 2 glasses of alcohol a day may increase your risk of breast cancer.


Women who’ve never had children or who had them only 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.


Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s – 1960s.

Hormone replacement therapy (HRT)

You have a higher risk of breast cancer if you’ve received hormone replacement therapy with estrogen for several years or more.


Obesity has been linked to breast cancer, although this link is not completely understood. The theory is that obese women produce more estrogen. This can fuel the development of breast cancer.


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 radiation and the higher the dose, the higher your risk. This is especially true if the radiation was given during breast development.

Breast implants, using antiperspirants, and wearing underwire bras don’t raise the risk of breast cancer. There is also no evidence of a direct link between breast cancer and pesticides.


Early breast cancer usually doesn’t 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, either bloody, clear to yellow, green, or like pus

As the cancer grows, symptoms may include:

Swelling of in the armpit (next to the breast with cancer)

Bone pain

Breast pain or discomfort

Skin ulcers

Weight loss


The doctor will ask you about your symptoms and risk factors. He or she will then give you a physical exam of both breasts, armpits, and the neck and chest area.

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

Fine needle aspiration biopsy

In fine needle aspiration biopsy (FNAB), the doctor (a pathologist, radiologist, or surgeon) uses a very thin needle attached to a syringe to withdraw (aspirate) a small amount of tissue from the suspicious area. This tissue is then looked at under a microscope. The needle used for FNAB is thinner than the ones used for blood tests.

If the area to be biopsied can be felt, the doctor locates the lump or suspicious area and guides the needle there. If the lump can’t be felt, the doctor might use ultrasound to watch the needle on a screen as it moves toward and into the mass. (This is called an ultrasound-guided biopsy.

Sentinel lymph node biopsy to check if the cancer has spread to the lymph nodes

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

CT scan to check if the cancer has spread

Mammography to screen for breast cancer or help identify the breast lump

PET scan to check if the cancer has spread

If your doctor learns that you do have breast cancer, more tests will be done. This is to check if the cancer has spread and is called staging. Staging 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 the type and stage of the cancer, whether the cancer is sensitive to certain hormones, and whether the cancer overproduces (overexpresses) a gene called HER2/neu.

Cancer treatments may include:

Chemotherapy medicines to kill cancer cells

Radiation therapy to destroy cancerous tissue

Surgery to remove cancerous tissue -- a lumpectomy removes the breast lump; mastectomyremoves all or part of the breast and possible nearby structures

Since estrogen allows breast cancer cells to survive and grow, hormone therapy is prescribed to women with ER-positive breast cancer to block certain hormones that fuel cancer growth. Targeted therapy, also called biologic therapy, on the other hand, uses special anticancer drugs that target certain changes in a cell that can lead to cancer.

Cancer treatment can be local or systemic. Local treatments, such as radiation and surgery, involve only the area of disease, are forms of local treatment. Systemic treatments such as chemotherapy affect the entire body.

Most women receive a combination of treatments. For women with stage I, II, or III breast cancer, the main goal is to treat the cancer and prevent it from returning. For women with stage IV cancer, the goal is to improve symptoms and help them live longer. In most cases, stage IV breast cancer cannot be cured.

Treatments for Different Stages of Cancer:

Stage 0 and DCIS

Lumpectomy plus radiation or mastectomy is the standard treatment. Doctors don’t quite agree on how best to treat DCIS.

Stage I and II

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 III

Treatment involves surgery, possibly followed by chemotherapy, hormone therapy, and biologic therapy.

Stage IV

Treatment may involve surgery, radiation, chemotherapy, hormone therapy, or a combination of these treatments.

Some women will continue to take medication after treatment, and all women will continue to have blood tests, mammograms, and other tests.


New, improved treatments are helping women 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. The more advanced your cancer, the poorer the outcome.

Factors used to determine successful treatment include:

Tumor size and shape

Gene expression

Tumor markers, such as HER2

Whether the tumor is hormone receptor-positive or -negative

Location of the tumor and how far it has spread

Rate of cell division or how quickly the tumor is growing


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

Lymphedema may start 6 to 8 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.


Women at very high risk of breast cancer may consider preventive mastectomy. Possible candidates include women who’ve already had one breast removed due to cancer, women with a strong family history of breast cancer, or women with genes or genetic mutations that raise their risk of breast cancer (such as BRCA1 or BRCA2).

Many risk factors, such as your genes and family history, cannot be controlled. But making healthy lifestyle changes, such as quitting smoking, getting in shape, limiting alcohol and eating a diet high in fruits, vegetables and whole grains and low in processed and red meat, may reduce your overall chance of getting cancer.