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 (NCI) has written this booklet to help patients with breast cancer and their families and friends better understand this disease. We hope others will read it as well to learn more about breast cancer.

This booklet discusses screening and early detection, symptoms, diagnosis, treatment, and rehabilitation. It also has information to help patients cope with breast cancer.

Words that may be new to readers are printed in italics. Definitions of these and other terms related to breast cancer are listed in the Glossary section. For some words, a “sounds-like” spelling is also given.

Male Breast Cancer

Breast cancer affects more than 1,000 men in this country each year. Although this booklet was written mainly for women, much of the information on symptoms, diagnosis, treatment, and living with the disease applies to men as well. (The Early Detection section does not apply to men. Experts do not recommend routine screening for men.)
 
Cancer research has led to real progress against breast cancer–better survival and improved quality of life. And knowledge about breast cancer is increasing. The Cancer Information Service and other NCI resources listed in the National Cancer Institute Information Resources section can provide the latest, most accurate information on breast cancer.

The CIS staff uses a National Cancer Institute cancer information database called PDQ and other NCI resources to answer callers’ questions. The staff can send callers information from PDQ and other NCI materials about cancer, its treatment, and living with the disease, including those listed in the Other Booklets section.

The Breasts

Each breast has 15 to 20 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 organs called lymph nodes. Clusters of lymph nodes are found near the breast 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

The most common type of breast cancer begins in the lining of the ducts and is called ductal carcinoma. Another type, called lobular carcinoma, arises in the lobules.

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–via the lymphatic system or the bloodstream.

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.

Risk Factors for Breast Cancer

The risk of breast cancer increases gradually as a woman gets older. This disease is uncommon in women under the age of 35. All women age 40 and older are at risk for breast cancer. However, most breast cancers occur in women over the age of 50, and the risk is especially high for women over age 60.

Research has shown that the following conditions place a woman at increased risk for breast cancer:

• Personal history of breast cancer. Women who have had breast cancer face an increased risk of getting breast cancer again.
• Genetic alterations. Changes in certain genes (BRCA1, BRCA2, and others) make women more susceptible to breast cancer. In families in which many women have had the disease, gene testing can show whether a woman has specific genetic changes known to increase the susceptibility to breast cancer. Doctors may suggest ways to try to delay or prevent breast cancer, or improve the detection of breast cancer in women who have the genetic alterations. For more information about gene testing, read the Causes and Prevention section under The Promise of Cancer Research.
• Family history. A woman’s risk for developing breast cancer increases if her mother, sister, daughter, or two or more other close relatives, such as cousins, have a history of breast cancer, especially at a young age.
• Certain breast changes. Having a diagnosis of atypical hyperplasia or lobular carcinoma in situ (LCIS) or having had two or more breast biopsies for other benign conditions may increase a woman’s risk for developing cancer.

Other factors associated with an increased risk for breast cancer include:

• Breast density. Women age 45 and older whose mammograms show at least 75 percent dense tissue are at increased risk. Dense breasts contain many glands and ligaments, which makes breast tumors difficult to “see,” and the dense tissue itself is associated with an increased chance of developing breast cancer.
• Radiation therapy. Women whose breasts were exposed to radiation during their childhood, especially those who were treated with radiation for Hodgkin’s disease, are at an increased risk for developing breast cancer throughout their lives. Studies show that the younger a woman was when she received her treatment, the higher her risk for developing breast cancer later in life.
• Late childbearing. Women who had their first child after the age of 30 have a greater chance of developing breast cancer than women who had their children at a younger age.

Also at a somewhat increased risk for developing breast cancer are women who started menstruating at an early age (before age 12), experienced menopause late (after age 55), never had children, or took hormone replacement therapy or birth control pills for long periods of time. Each of these factors increases the amount of time a woman’s body is exposed to estrogen. The longer this exposure, the more likely she is to develop breast cancer.

In most cases, doctors cannot explain why a woman develops breast cancer. Studies show that most women who develop breast cancer have none of the risk factors listed above, other than the risk that comes with growing older. Also, most women with known risk factors do not get breast cancer. Scientists are conducting research into the causes of breast cancer to learn more about risk factors and ways of preventing this disease.

Early Detection

When breast cancer is found and treated early, the chances for survival are better. Women can take an active part in the early detection of breast cancer by having regular screening mammograms and clinical breast exams (breast exams performed by health professionals). Some women also perform breast self-exams.

A screening mammogram is the best tool available for finding breast cancer early, before symptoms appear. 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. Screening mammograms are used to look for breast changes in women who have no signs of breast cancer.

Mammograms can often detect breast cancer before it can be felt. Also, a mammogram can 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.

Although mammograms are the best way to find breast cancer early, they do have some limitations. A mammogram may miss some cancers that are present (false negative) or may find things that turn out not to be cancer (false positive). And detecting a tumor early does not guarantee that a woman’s life will be saved. Some fast-growing cancers may already have spread to other parts of the body before being detected.

Still, regularly scheduled screening mammograms, together with clinical breast exams, offer the best chance of finding and treating breast cancer early. Studies show that mammograms reduce the risk of dying from breast cancer. The National Cancer Institute recommends that women in their forties and older have mammograms on a regular basis, every 1 to 2 years.

Women should talk with their doctor about factors that can increase the risk for breast cancer. Women of any age who are at higher risk for this disease should ask their doctor when to begin and how often to have screening mammograms and breast exams.

Some women perform monthly breast self-exams to check for any changes in their breasts. When doing a breast self-exam, it’s important to remember that each woman’s breasts are different, and that changes can occur 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. Remember that for women in their forties and older, a monthly breast self-exam is not a substitute for regularly scheduled screening mammograms and clinical breast exams by a health professional.

Symptoms

Early breast cancer usually does not cause pain. In fact, when breast cancer first develops, there may be no symptoms at all. But as the cancer grows, it can cause changes that women should watch for: