Types and Grades of Breast Cancer

Breast cancers fall into two main categories:

• In situ cancers, also called noninvasive cancers, are the confined to the area of the body where they originally developed, in this case, the breast. The term in situ is Latin for "in the same place."
• Invasive cancers are those in which the cancer has metastasized to other areas of the body. Invasive breast cancers typically spread to the bones, lungs, liver, and brain.

In addition, breast cancer grading is a system used for invasive cancers that describes how closely the cancer resembles normal breast cells.

In their most recent findings, the American Cancer Society estimated that for 2007 an estimated 178, 480 new cases of invasive breast cancer would be diagnosed among women, as well as an estimated 62,030 additional cases of in situ breast cancer.

In Situ Breast Cancer

Ductal Carcinoma in Situ (DCIS)

Ductal carcinoma in situ is a pre-cancerous condition in which abnormal cells are confined to the milk ducts in the breast. Most noninvasive breast cancers are DCIS—according to the American Cancer Society, of the in situ breast cancers diagnosed from 2000-2004, 80 percent were DCIS.

Many women diagnosed at this early stage of breast cancer can be cured by removing the tissue that contains the tumor. If left untreated, DCIS can become invasive. Because DCIS typically has no physical signs or symptoms, it is usually detected by a screening mammogram.

Lobular Carcinoma in Situ (LCIS)

Cancer that begins in the lobes or lobules of the breast is called lobular carcinoma and is more often found in both breasts than are other types of breast cancer. Many oncologists believe that LCIS is not a true cancer but instead an indicator of increased risk for developing invasive cancer in the future. 

Invasive Breast Cancer

The following are the most common types of invasive breast cancer.

Invasive Ductal Carcinoma (IDC)

About 80 percent of all breast cancers are invasive ductal carcinomas. IDC begins in a duct in the breast and breaks through into the surrounding fatty tissue of the breast. From here IDC can metastasize to other parts of the body through the bloodstream or lymphatic system.

Invasive Lobular Carcinoma (ILC)

Invasive lobular carcinoma is the second most common type of invasive breast cancer. ILC starts in the milk-producing glands (lobules) and, like IDC, can spread to other parts of the body.

Inflammatory Breast Cancer (IBC)

Only about 1 percent of all women diagnosed with breast cancer have inflammatory breast cancer. This rare cancer is very aggressive and progresses rapidly, leaving the breast red, swollen, and warm to the touch. The surface of the breast may look pitted like the skin of an orange, as the cancer cells block lymph vessels in the skin. Typically there is no single lump in the breast.

In its early stages, IBC can be mistaken for infection, because the symptoms are similar to inflammatory breast cancer. However, most infections will respond to antibiotics while inflammatory breast cancer will not.

IBC occurs more frequently in African Americans and at a younger age than in Caucasians. It too can occur in men, usually at an older age.

Breast Cancer Grade

The grade of a tumor refers to how closely the cancer resembles normal breast cells. It is a system used for invasive cancers but not for in situ cancers. In general, a lower grade number indicates a slower-growing cancer that is less likely to spread, while a higher number indicates a faster-growing cancer that is more likely to spread.

Grade 1 (well differentiated): Grade 1 breast cancers have relatively normal-looking cells that do not appear to be growing rapidly and are arranged in small tubules.

Grade 2 (moderately differentiated): These cancers have cells that are somewhat abnormal.

Grade 3 (poorly differentiated): The highest grade, these cancers have cells that look abnormal and tend to grow and spread more aggressively. 
 

Updated 8/18/2009