Breast cancer

Breast cancer is cancer that begins in the cells of the breast. It typically originates in the lobules (the milk producing glands) or ducts (the tiny tubes that carry the milk to the nipple). Breast cancer can occur in women and men but is rare in men.

Breast cancer is classified as either

  • Non-invasive (in situ)- this is cancer confined to the lobule or duct.
  • Invasive (infiltrating)- this is cancer that has spread beyond the lobule or duct to neighboring/nearby tissue.


The first symptom of breast cancer is typically a hard lump discovered in the breast or armpit. Additional symptoms may include

  • Changes in breast skin texture
  • Retraction or indentation of the nipple
  • Discharge from the nipple

If you notice any unusual changes in your breasts, you should visit a doctor as soon as possible.


The American Cancer Society recommends regular breast exams to help diagnosis breast cancer early. If your doctor detects an abnormality during a routine breast exam, they will then most likely recommend that you get a mammogram. This screening method uses x-rays to take a picture of the breasts. MRIs and ultrasounds are also used to detect tumors and examine abnormalities.

If a lump or mass is discovered, a biopsy will be performed. A sample of affected breast will be sent to a lab for examination. If cancerous cells are present, doctors can confirm a diagnosis.

Breast cancer screening

A mammogram is the best screening exam for detecting breast cancer. The current recommendations for starting age and how often regular screenings should begin varies among health professionals. The decision to begin mammogram screenings should be an individual one made by you and your doctor. 


Several factors are used to determine the risk of cancer recurrence and the likelihood of successful treatment.

A few of these factors include:

  • Size and shape of the tumor
  • How far it has spread
  • Rate of cell division
  • Which hormones, if any, stimulate the growth of the cancer

Breast cancer survival rates are based on how advanced the cancer is and when it is first diagnosed. For cancer that is confined to the primary site (in situ) 5-year survival rates are about 99%.


Three main methods are used to treat breast cancer.

  • Surgery
  • Radiation
  • Drug therapy

Most often a combination of treatment is given. The chosen treatment method is determined by many factors, including the age and menopausal status of the patient, and the stage of the cancer.

How cancer stages are determined

  • The size and location of the tumor
  •  If the tumor has spread to the lymph nodes
  • If the cancer has spread to other parts of the body

Breast cancer treatment is very personal and differs greatly from patient to patient. Many options are available and should be thoroughly discussed between the medical team and the patient.

Who is at risk?

One in eight women will develop invasive breast cancer in their lifetime. Factors such as age, race/ethnicity, family history and genetics can also increase your risk of developing breast cancer.

  • Age- Most often breast cancer occurs in those over the age of 50.
  • Race and ethnicity- In the United States breast cancer is most common in white women.
  • Family history- Having a first-degree relative who was diagnosed with breast cancer nearly doubles the risk of developing breast cancer.
  • Genetics- Between 5 and 10 percent of breast cancer is due to an inherited genetic mutation. The inherited genes BRCA1 and BRCA2 are the cause of most hereditary breast and ovarian cancers.

Additional risk factors

Exposure to estrogen

Breast tissue growth is dependent on estrogen. The more estrogen a woman is exposed to throughout her lifetime the higher her risk is of developing breast cancer. Because of this, women who experience their first period early or menopause late have a slightly increased risk of developing breast cancer.

  • Birth control pills- Evidence shows oral contraceptives may increase a woman’s risk slightly but that risk declines once a woman stops using oral contraceptives.
  • Hormone therapy (HT)- Hormone therapy is used to treat symptoms of menopause. Women at a high risk for breast cancer should not take HT. Starting HT past the age of 59 may increase a woman’s risk of breast cancer.
  • Physical characteristics- Obesity increases your overall risk of cancer, although it is a specific risk factor for estrogen receptor-positive types of breast cancer. High amounts of fat tissue increase estrogen levels in the body.

Breast tissue type

Certain types of breast tissue can increase your risk of developing breast cancer. Your doctor can determine if this may be a risk factor for you.

Lifestyle factors

Women who have two or more alcoholic drinks per day have a 50 percent increase in their breast cancer risk compared to those who don’t.

Genetics of breast cancer

Mutations in the inherited genes BRCA1 and BRCA2 are the cause of most hereditary breast and ovarian cancers. BRCA mutations are present in about 0.5 percent of the overall population and can occur in those of all ethnic backgrounds. Jewish women of Eastern European decent have a higher prevalence (2.5 percent) of BRCA mutations.

Genetic screening

Those who have a family history of breast cancer or a history that suggests a high risk for BRCA mutations are encouraged to test for BRCA genetic mutations.

Indications of increased risk:

  • Having several first- or second-degree relatives who have had breast or ovarian cancer
  • Breast cancer diagnosed before age 50
  • Cancer in both breasts
  • Breast cancer in a male relative

If you feel you are at risk, talk with your health care provider. They may refer you to a genetic counselor who can discuss whether you should be tested.

Breast cancer prevention

The American Cancer Society guidelines for cancer prevention recommend achieving and maintaining a healthy weight throughout life.

  • Exercise- Since exercise can help reduce body fat, it can help reduce breast cancer-promoting hormones such as estrogen. The ACS recommends getting as least 150 minutes of moderate activity or 75 minutes of vigorous activity per week.
  • Dietary factors recommendations
    • Choose foods and serving sizes that promote a healthy weight.
    • Eat at least 2 to 3 cups of fruits and vegetables per day.
    • Choose whole grains over refined grains.
    • Limit your consumption of processed meat, red meat, and alcohol (one drink per day).

Prevention for those at high risk 

The following recommendations may be helpful for those with a high risk of developing breast cancer.

  • Use alternatives to oral contraceptives and have children early in life.
  • Avoid hormone therapy if possible.
  • Discuss preventative medication options with your doctor.
  • Consider avoiding alcohol.

Preventative surgery

For those at very high risk due to genetics, a mastectomy may be an option to significantly reduce that risk. During this operation a doctor will remove both breasts. Removal of the ovaries and fallopian tubes can also reduce the risk for breast cancer and significantly reduce the risk of ovarian cancer.

Last reviewed: 
September 2018

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