General Information about Breast Cancer

Breast cancer is the most common type of cancer among women in the United States (other than skin cancer). Each year, more than 180,000 women in this country learn they have breast cancer. The National Cancer Institute has written this leaflet to help patients with breast cancer and their families and friends better understand this disease.

Male Breast Cancer

Breast cancer also affects more than 1,000 men in this country each year. Although this material was written mainly for women, much of the information about this disease applies to men as well. (However, experts do not recommend routine screening for men.)

Our knowledge about breast cancer keeps increasing. For up-to-date information, call the National Cancer Institute's Cancer Information Service (CIS). The toll-free number is 1-800-4-CANCER (1-800-422-6237). The CIS staff uses a National Cancer Institute cancer information database called Physician Data Query (PDQ) and other National Cancer Institute resources to answer callers' questions. The staff can send callers information from PDQ and other National Cancer Institute materials about cancer, its treatment, and living with the disease.

What Is Cancer?

Cancer is a group of diseases that occur when cells become abnormal and divide without control or order. Every organ in the body is made up of various kinds of cells. Cells normally divide in an orderly way to produce more cells only when they are needed. This process helps keep the body healthy. If cells divide when new cells are not needed, they form too much tissue. The mass or lump of extra tissue, called a tumor, can be benign or malignant.

Benign tumors are not cancer. They can usually be removed, and in most cases, they don't come back. Most important, the cells in benign tumors do not invade other tissues and do not spread to other parts of the body. Benign breast tumors are not a threat to life.

Malignant tumors are cancer. The cancer cells grow and divide out of control. They can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system. That is how breast cancer spreads and forms secondary tumors in other parts of the body. The spread of cancer is called metastasis.

The Breasts

Each breast has 6 to 9 overlapping sections called lobes. Within each lobe are many smaller lobules, which end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are all linked by thin tubes called ducts. These ducts lead to the nipple in the center of a dark area of skin called the areola. Fat fills the spaces around the lobules and ducts. There are no muscles in the breast, but muscles lie under each breast and cover the ribs.

Each breast also contains blood vessels and vessels that carry colorless fluid called lymph. The lymph vessels lead to small bean-shaped structures called lymph nodes. Clusters of lymph nodes are found in the axilla (under the arm), above the collarbone, and in the chest. Lymph nodes are also found in many other parts of the body.

Types Of Breast Cancer

There are several types of breast cancer. The most common one begins in the lining of the ducts and is called ductal carcinoma. Another type, called lobular carcinoma, arises in the lobules. Other cancers that begin in the breast are rare and are not discussed here. The Cancer Information Service can supply information about them.

When breast cancer spreads outside the breast, cancer cells are often found in the lymph nodes under the arm (axillary lymph nodes). If the cancer has reached these nodes, it may mean that cancer cells have spread to other parts of the body—other lymph nodes and other organs, such as the bones, liver, or lungs.

Cancer that spreads is the same disease and has the same name as the original (primary) cancer. When breast cancer spreads, it is called metastatic breast cancer, even though the secondary tumor is in another organ. Doctors sometimes call this "distant" disease.

Screening and Early Detection

Women can take an active part in the early detection of breast cancer. They should talk with their doctor about the symptoms to watch for and an appropriate schedule of checkups. The doctor's advice will be based on the woman's age, medical history, and other factors. Women should ask the doctor about:

• Mammograms (x-rays of the breast).
• Clinical breast exams (breast exams by a doctor or nurse).
• Breast self-examination.

A mammogram is a special kind of x-ray. It is different from a chest x-ray or x-rays of other parts of the body. Mammography performed in women with no symptoms of breast cancer is usually called screening. Although mammography cannot find every breast cancer, it is currently the best early detection tool available. Studies show that having mammograms regularly (not just once) saves lives in women aged 50 and older. Experts disagree about whether women under 50 should have regular mammograms. It is important for each woman to discuss mammography with her doctor so they can decide together what is right for her.

Mammography uses very low levels of radiation. It usually involves two x-rays of each breast, one taken from the side and one from the top. The breast must be squeezed between two plates for the pictures to be clear. While this squeezing may be a bit uncomfortable, it lasts only a few seconds. In many cases (but not all), mammograms can show breast tumors before they cause symptoms or can be felt. A mammogram can also show small deposits of calcium in the breast. Although most calcium deposits are benign, a cluster of very tiny specks of calcium (called microcalcifications) may be an early sign of cancer.

Mammography should be done only by specially trained medical staff using approved machines designed just for taking x-rays of the breast. A qualified doctor, called a radiologist, should read the mammogram. The results should be communicated promptly to the woman by the mammography facility or by her own doctor. The Mammography Quality Standards Act is a Federal law requiring that all mammography facilities be certified. Women should talk with their doctor or call the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237) for help in finding a certified mammography facility.

For women of all ages, a breast exam by a doctor or nurse (called a clinical breast exam) is usually part of the regular medical checkup. Remember, however, that for women over 50, a clinical breast exam is no substitute for regular mammography.

Also, many women choose to examine their own breasts once a month. It's important to remember that every woman's breasts are different. And each woman's breasts change because of aging, the menstrual cycle, pregnancy, menopause, or taking birth control pills or other hormones. It is normal for the breasts to feel a little lumpy and uneven. Also, it is common for a woman's breasts to be swollen and tender right before or during her menstrual period. A woman should contact her doctor about any unusual changes in her breasts, whether she notices them during breast self-exam or at another time. And, again, remember that for women over 50, a breast self-exam is not a substitute for regular screening mammography.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.