Breast Cancer

Breast cancer is a condition in which abnormal cell growth occurs in the breast. While it can affect men, the disease is more common in women. The causes of breast cancer are unknown, but family history of the disease and dense breast tissue are possible risk factors. Most women who are treated early for the condition resume healthy, active lives, although the risk of recurrence is present.

 

An Introduction to Breast Cancer

Women in the United States get breast cancer more than any other type of cancer, except for skin cancer. Each year, more than 200,000 American women learn they have the disease and over 40,000 women die from it.
 
Breast cancer is second only to lung cancer as a cause of cancer death in women. It occurs in men also, but the number of cases is smaller (see Male Breast Cancer).
 

What Is Cancer?

Cancer is a group of more than 100 different diseases. It occurs when, for unknown reasons, cells become abnormal and divide without control or order. All parts of the body are made up of cells that normally divide to produce more cells, but only when the body needs them. With cancer, cells keep dividing, even when new cells are not needed.
 
The change from normal to cancerous cells requires several separate, different gene alterations. Eventually, altered genes and uncontrolled growth may produce a tumor that can be benign (not cancerous) or malignant (cancerous). Malignant tumors can invade, damage, and destroy nearby tissues and spread to other parts of the body. A benign tumor won't spread to other parts of the body, but local tissue may be damaged and the growth may need to be removed.
 
Cancer cells can also break away from a malignant tumor and enter the bloodstream or the lymphatic system. This is how the condition spreads within the body. When breast cancer spreads outside the breast, cancer cells often are found in the lymph nodes under the arm. They can also spread to other lymph nodes, the bones, liver, or lungs. Although it is not common, some people whose underarm lymph nodes are clear of breast cancer may still have cancer cells that have spread to other parts of the body.
 
Cancer that spreads to other parts of the body is the same disease and has the same name as the original cancer. For example, breast cancer that has spread to the bones is called metastatic breast cancer, not bone cancer.
 

Understanding the Breasts

The breasts sit on the chest muscles that cover the ribs. The breast is made up of lobes and ducts. Each breast has 15 to 20 sections, called lobes, which have many smaller sections called lobules. Lobules end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are linked by thin tubes called ducts. Milk flows from the lobules through these ducts to the nipple. The nipple is in the center of a dark area of skin called the areola. Fat fills the spaces between the lobules and ducts.
 
Each breast also contains blood vessels and lymph vessels. The lymph vessels carry an almost colorless fluid called lymph. These vessels lead to organs called lymph nodes. In breast cancer, the cancer cells can spread outside the breast into the lymph nodes under the arm. In many cases, if the cancer has reached the lymph nodes, cancer cells may have also spread to other parts of the body via the lymphatic system or through the bloodstream.
 
(Click Breast Anatomy for more information.)
 

Types of Breast Cancer

Breast cancer can be invasive (moves into the surrounding tissue) or non-invasive (stays in the ducts or lobes). Invasive breast cancers make up 70 to 80 percent of all cases. The most common type of invasive breast cancer is infiltrating ductal carcinoma (also called invasive ductal carcinoma). This type is found in approximately 60 percent of cases.
 
Other types of breast cancer include:
 

Causes of Breast Cancer

Most breast cancer causes are unknown. In 5 to 10 percent of these cases, there is a hereditary component.
 
 

Risk Factors for Breast Cancer

Anything that increases your chance of getting a disease is called a risk factor. Breast cancer risk factors include:
 
  • Older age
  • Early menarche (menstruation)
  • Older age at first birth or never having given birth
  • A personal history of breast cancer or benign (noncancerous) breast disease
  • A mother or sister with breast cancer
  • Treatment with radiation therapy to the breast/chest
  • Breast tissue that is dense on a mammogram
  • Hormone use (such as estrogen and progesterone)
  • Excessive drinking of alcoholic beverages
  • Being Caucasian.

 

(Click Breast Cancer Risk Factors for more information.)

 

Symptoms of Breast Cancer

Not everyone with breast cancer will have early symptoms of the disease. That is why screening is so important. It can help doctors find and treat cancer early. Also, treatment is more likely to work well when the disease is found early.
 
(Click Breast Cancer Symptoms for more information.)
 

Diagnosing Breast Cancer

If a woman has possible symptoms of breast cancer, her healthcare provider will ask a number of questions and perform a physical exam looking for signs of the disease. He or she may also recommend certain tests or procedures, including:
 
  • Mammogram
  • Ultrasound
  • MRI
  • Biopsy
  • Fine-needle aspiration.
     

Stages of Breast Cancer

Breast cancer is a complex disease. All cases are not the same. Once the disease has been found, more tests will be done to find out the specific pattern. This important step is called staging. Knowing the exact stage will help your healthcare provider plan your treatment.
 
Your healthcare provider will want to know:
 
  • The size of the tumor and exactly where it is in your breast
  • If the cancer has spread within your breast
  • If cancer is present in your lymph nodes under your arm
  • If cancer is present in other parts of your body.
     
Specific breast cancer stages include:
 
  • Stage 0 (including lobular carcinoma in situ and ductal carcinoma in situ)
  • Stage I
  • Stage II (including IIA and IIB)
  • Stage III (including IIIA, IIIB, and IIIC)
  • Stage IV
  • Recurrent.
     

Treating Breast Cancer

Women with breast cancer have many treatment options available to them. These options include:
 
Many women receive more than one type of treatment, and the choice of treatment depends mainly on the disease's stage (see Breast Cancer Treatment by Stage).
 
Some of these treatments are considered primary, where the purpose is to remove the tumor. Others are considered adjuvant therapy, which is treatment given to kill any tumor cells that may have spread and to increase the chances for a cure (see Adjuvant Therapy for Breast Cancer).
 
Your healthcare provider can describe your treatment choices and the expected results. Then, the two of you can work together to develop a treatment plan that reflects your medical needs and personal values.
 

What Is the Prognosis for Breast Cancer?

Most women who are treated for early breast cancer go on to live healthy, active lives. You may have more choices when it comes to treatment if the disease is found early.
 
Breast cancer treatments have changed over time. Today, many women who are diagnosed with it do not have to lose a breast. Because there are improved ways to treat the disease, it is more important than ever for you to learn all you can. Working with your team of medical specialists, you can play a key role in choosing the treatment that is best for you.
 
(Click Breast Cancer Prognosis or Breast Cancer Survival Rate for more information.)
 

Risk Factors for Recurrence of Breast Cancer

Your chance of surviving breast cancer will depend on your chance of the disease returning after treatment is completed. Some women are at a higher risk for the spread or return of breast cancer. In many cases, doctors can't explain why one person stays well and another does not.
 
Remember, the risk factors for recurrence are complex. They are not absolute predictions of your future health. Some factors that affect the spread or recurrence of the disease are:
 
  • Tumor size: The smaller your tumor, the lower the risk
  • Lymph nodes: The fewer underarm lymph nodes that have cancer, the lower your risk
  • Cell growth: Cancer cells that grow slowly are linked to a lower risk
  • Hormones: If a tumor depends on hormones for growth, hormonal therapy can lower the risk of the cancer spreading or recurring.
     

Preventing Breast Cancer

Early detection and effective treatment methods are expected to reduce the number of women who die from breast cancer. Researchers are continuing to develop new methods for preventing this disease.
 
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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD