What You Need To Know About Breast Cancer

by National Cancer Institute

Introduction

You will read about possible causes, screening, symptoms, diagnosis, treatment, and supportive care. You will also find ideas about how to cope with the disease.

Scientists are studying breast cancer to find out more about its causes. And they are looking for better ways to prevent, find, and treat it.

The Breasts

The breasts sit on the chest muscles that cover the ribs. Each breast is made of 15 to 20 lobes. Lobes contain many smaller lobules. Lobules contain groups of tiny glands that can produce milk. Milk flows from the lobules through thin tubes called 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.

The breasts also contain lymph vessels. These vessels lead to small, round organs called lymph nodes. Groups of lymph nodes are near the breast in the axilla (underarm), above the collarbone, in the chest behind the breastbone, and in many other parts of the body. The lymph nodes trap bacteria, cancer cells, or other harmful substances.

Understanding Cancer

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.

Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.

Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Tumors can be benign or malignant:

Benign tumors are not cancer:

• Benign tumors are rarely life-threatening.
• Generally, benign tumors can be removed. They usually do not grow back.
• Cells from benign tumors do not invade the tissues around them.
• Cells from benign tumors do not spread to other parts of the body.

Malignant tumors are cancer:

• Malignant tumors are generally more serious than benign tumors. They may be life-threatening.

• Malignant tumors often can be removed. But sometimes they grow back.

• Cells from malignant tumors can invade and damage nearby tissues and organs.

• Cells from malignant tumors can spread (metastasize) to other parts of the body. Cancer cells spread by breaking away from the original (primary) tumor and entering the bloodstream or lymphatic system. The cells invade other organs and form new tumors that damage these organs. The spread of cancer is called metastasis.

When breast cancer cells spread, the cancer cells are often found in lymph nodes near the breast. Also, breast cancer can spread to almost any other part of the body. The most common are the bones, liver, lungs, and brain. The new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer. For that reason, it is treated as breast cancer, not bone cancer. Doctors call the new tumor "distant" or metastatic disease.

Risk Factors

No one knows the exact causes of breast cancer. Doctors often cannot explain why one woman develops breast cancer and another does not. They do know that bumping, bruising, or touching the breast does not cause cancer. And breast cancer is not contagious. You cannot "catch" it from another person.

Research has shown 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 developing a disease.

Studies have found the following risk factors for breast cancer:

Age: The chance of getting breast cancer goes up as a woman gets older. Most cases of breast cancer occur in women over 60. This disease is not common before menopause.

Personal history of breast cancer: A woman who had breast cancer in one breast has an increased risk of getting cancer in her other breast.

Family history: A woman's risk of breast cancer is higher if her mother, sister, or daughter had breast cancer. The risk is higher if her family member got breast cancer before age 40. Having other relatives with breast cancer (in either her mother's or father's family) may also increase a woman's risk.

Certain breast changes: Some women have cells in the breast that look abnormal under a microscope. Having certain types of abnormal cells (atypical hyperplasia and lobular carcinoma in situ [LCIS]) increases the risk of breast cancer.

Gene changes: Changes in certain genes increase the risk of breast cancer. These genes include BRCA1, BRCA2, and others. Tests can sometimes show the presence of specific gene changes in families with many women who have had breast cancer. 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 changes in their genes. NCI offers publications on gene testing.

Reproductive and menstrual history:

• The older a woman is when she has her first child, the greater her chance 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 never had children are at an increased risk of breast cancer.

• Women who take menopausal hormone therapy with estrogen plus progestin after menopause also appear to have an increased risk of breast cancer.

• Large, well-designed studies have shown no link between abortion or miscarriage and breast cancer.

About the Author

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