Health Guide Directory > Breast Cancer Resources


Learn about causes of Breast Cancer and risk factors.
Find information about early detection of Breast Cancer.

What Is Breast Cancer?
Breast cancer is a malignant (cancerous) tumor that starts from cells of the breast. The disease occurs mostly in women, but men can get breast cancer as well. The information here refers only to breast cancer in women.

The breast itself is made up of lobules, ducts, fatty and connective tissue, blood vessels, and lymph (limf) vessels. Lymph vessels are like veins, except that they carry lymph fluid instead of blood. Inside the breasts are glands that produce and release milk after a woman has a baby. The glands that make the milk are called lobules and the tubes that connect them to the nipple are called ducts.

Lymph is a clear fluid that contains immune system cells and tissue waste products. The fluid is carried in lymph vessels that lead to small, pea-sized collections of tissue called lymph nodes. Most lymphatic vessels of the breast lead to lymph nodes under the arm. These are called axillary nodes.

When breast cancer cells reach the underarm lymph nodes and continue to grow, they cause the nodes to swell. Once cancer cells have reached these nodes they are more likely to spread to other organs of the body as well.

There are several types of breast tumors. Most are benign; that is, they are not cancer. Benign breast tumors are abnormal growths, but they do not spread outside of the breast and they are not life threatening.

Some lumps aren't really tumors at all. These lumps are often caused by fibrocystic changes. Cysts are fluid-filled sacs. Fibrosis refers to the formation of connective tissue or scar tissue. Such changes can cause breast swelling and pain. The breasts may feel lumpy and sometimes there is a clear or slightly cloudy nipple discharge. The American Cancer Society has a separate document on "Benign Breast Conditions" available through our toll-free number or on our web site.

Understanding the medical language as it relates to breast cancer can be challenging. Here are some terms that describe the most common types of breast cancer:

In situ (in SIGH-to): This term is used for the early stage of cancer, when it is confined to the place where it started. In breast cancer, it means that the cancer is confined to the ducts or the lobules, depending on where it started. It has not gone into the fatty tissues in the breast nor spread to other organs in the body.

Ductal carcinoma in situ (DCIS): This is the most common type of noninvasive breast cancer. DCIS means that the cancer is confined to the ducts. It has not spread through the walls of the ducts into the fatty tissue of the breast. Nearly all women with cancer at this stage can be cured. The best way to find DCIS early is with a mammogram.

Lobular carcinoma in situ (LCIS): Although not a true cancer, having LCIS increases a woman's risk of developing cancer later. For this reason, it's important that women with LCIS have a physical exam two or three times a year, as well as a mammogram every year.

Infiltrating (invasive) ductal carcinoma (IDC):
This cancer starts in a milk passage or duct, breaks through the wall of the duct, and invades the fatty tissue of the breast. From there it can spread to other parts of the body. IDC is the most common type of breast cancer. It accounts for about 80% of invasive breast cancer.

Infiltrating (invasive) lobular carcinoma (ILC):
This cancer starts in the milk glands or lobules. It can spread to other parts of the body. About 5% of invasive breast cancers are of this type. There are also several other less common types of breast cancer. You can get information about these through our toll-free number or on our Web site.