Breast Health Facts

Breast Anatomy

Inside a woman's breast are 15 to 20 sections called lobes. Each lobe is made of many smaller sections called lobules. Lobules have groups of tiny glands that can make milk. After a baby is born, a woman's breast milk flows from the lobules through thin tubes called ducts to the nipple. Fat and fibrous tissue fill the spaces between the lobules and ducts.

The breasts also contain lymph vessels. These vessels are connected to small, round masses of tissue called lymph nodes. Groups of lymph nodes are near the breast in the underarm (axilla), above the collarbone, and in the chest behind the breastbone. This picture shows the lobes and ducts inside the breast. It also shows the lymph nodes near the breast.

Breast Cancer Biology

Cancer cells

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the breasts and other parts of the body.

Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells take their place.

Sometimes, this process goes wrong. New cells form when the body doesn't need them, and old or damaged cells don't die as they should. The buildup of extra cells often forms a mass of tissue called a lump, growth, or tumor.

Tumors in the breast can be benign (not cancer) or malignant (cancer). Benign tumors are not as harmful as malignant tumors:

Benign tumors:

are rarely a threat to life
can be removed and usually don't grow back
don't invade the tissues around them
don't spread to other parts of the body

Malignant tumors:

may be a threat to life
often can be removed but sometimes grow back
can invade and damage nearby organs and tissues (such as the chest wall)
can spread to other parts of the body

Breast cancer cells can spread by breaking away from the original tumor. They enter blood vessels or lymph vessels, which branch into all the tissues of the body. The cancer cells may be found in lymph nodes near the breast. The cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues.

The spread of cancer is called metastasis. See the Staging section for information about breast cancer that has spread.

Risk Factors

When you're told that you have breast cancer, it's natural to wonder what may have caused the disease. But no one knows the exact causes of breast cancer. Doctors seldom know why one woman develops breast cancer and another doesn't.

Doctors do know that bumping, bruising, or touching the breast does not cause cancer. And breast cancer is not contagious. You can't catch it from another person.

Doctors also know that women with certain risk factors are more likely than others to develop breast cancer. A risk factor is something that may increase the chance of getting a disease.

Some risk factors (such as drinking alcohol) can be avoided. But most risk factors (such as having a family history of breast cancer) can't be avoided.

Studies have found the following risk factors for breast cancer:

Age: The chance of getting breast cancer increases as you get older. Most women are over 60 years old when they are diagnosed.
Personal health history: Having breast cancer in one breast increases your risk of getting cancer in your other breast. Also, having certain types of abnormal breast cells (atypical hyperplasia, lobular carcinoma in situ [LCIS], or ductal carcinoma in situ [DCIS]) increases the risk of invasive breast cancer. These conditions are found with a breast biopsy.
Family health history: Your risk of breast cancer is higher if your mother, father, sister, or daughter had breast cancer. The risk is even higher if your family member had breast cancer before age 50. Having other relatives (in either your mother's or father's family) with breast cancer or ovarian cancer may also increase your risk.
Certain genome changes: Changes in certain genes, such as BRCA1 or BRCA2, substantially increase the risk of breast cancer. Tests can sometimes show the presence of these rare, specific gene changes in families with many women who have had breast cancer, and health care providers may suggest ways to try to reduce the risk of breast cancer or to improve the detection of this disease in women who have these genetic changes.

Also, researchers have found specific regions on certain chromosomes that are linked to the risk of breast cancer. If a woman has a genetic change in one or more of these regions, the risk of breast cancer may be slightly increased. The risk increases with the number of genetic changes that are found. Although these genetic changes are more common among women than BRCA1 or BRCA2, the risk of breast cancer is far lower.

Radiation therapy to the chest: Women who had radiation therapy to the chest (including the breasts) before age 30 are at an increased risk of breast cancer. This includes women treated with radiation for Hodgkin lymphoma. Studies show that the younger a woman was when she received radiation treatment, the higher her risk of breast cancer later in life.
Reproductive and menstrual history:
- The older a woman is when she has her first child, the greater her chance of breast cancer.
- Women who never had children are at an increased risk of breast cancer.
- Women who had their first menstrual period before age 12 are at an increased risk of breast cancer.
- Women who went through menopause after age 55 are at an increased risk of breast cancer.
- Women who take menopausal hormone therapy for many years have an increased risk of breast cancer.
Race: In the United States, breast cancer is diagnosed more often in white women than in African American/black, Hispanic/Latina, Asian/Pacific Islander, or American Indian/Alaska Native women.
Breast density: Breasts appear on a mammogram (breast x-ray) as having areas of dense and fatty (not dense) tissue. Women whose mammograms show a larger area of dense tissue than the mammograms of women of the same age are at increased risk of breast cancer.
History of taking DES: DES was given to some pregnant women in the United States between about 1940 and 1971. (It is no longer given to pregnant women.) Women who took DES during pregnancy may have a slightly increased risk of breast cancer. The possible effects on their daughters are under study.
Being overweight or obese after menopause: The chance of getting breast cancer after menopause is higher in women who are overweight or obese.
Lack of physical activity: Women who are physically inactive throughout life may have an increased risk of breast cancer.
Drinking alcohol: Studies suggest that the more alcohol a woman drinks, the greater her risk of breast cancer.

Having a risk factor does not mean that a woman will get breast cancer. Most women who have risk factors never develop breast cancer.

Many other possible risk factors have been studied. For example, researchers are studying whether women who have a diet high in fat or who are exposed to certain substances in the environment have an increased risk of breast cancer. Researchers continue to study these and other possible risk factors.

Finding Breast Cancer

Early breast cancer usually doesn't cause symptoms. But as the tumor grows, it can change how the breast looks or feels. The common changes include:

A lump or thickening in or near the breast or in the underarm area
A change in the size or shape of the breast
Dimpling or puckering in the skin of the breast
A nipple turned inward into the breast
Discharge (fluid) from the nipple, especially if it's bloody
Scaly, red, or swollen skin on the breast, nipple, or areola (the dark area of skin at the center of the breast). The skin may have ridges or pitting so that it looks like the skin of an orange.

You should see your health care provider about any symptom that does not go away. Most often, these symptoms are not due to cancer. Another health problem could cause them. If you have any of these symptoms, you should tell your health care provider so that the problems can be diagnosed and treated.

Detection and Diagnosis

Your doctor can check for breast cancer before you have any symptoms. During an office visit, your doctor will ask about your personal and family medical history. You'll have a physical exam. Your doctor may order one or more imaging tests, such as a mammogram.

Doctors recommend that women have regular clinical breast exams and mammograms to find breast cancer early. Treatment is more likely to work well when breast cancer is detected early.

Source: The Web site of the National Cancer Institute (http://www.cancer.gov)