Normal Breast

The earliest stage of breast cancer is called ductal carcinoma in situ (DCIS). With current diagnostic techniques, this early stage is diagnosed frequently. Carcinoma in situ may also develop in the lobule -- lobular carcinoma in situ (LCIS). LCIS, unlike DCIS, is not considered a cancer, despite its name. Instead, it is viewed as an indication of increased risk, sometimes called a marker, for the subsequent development of invasive cancer. The cancer that may develop can arise in either breast and may not appear for 20 years, if ever.

The most common cancer of the breast is infiltrating ductal carcinoma. This cancer not only invades various breast structures, but also may spread to the lymph nodes under the arms (called axillary lymph nodes) and to other organs. Microscopically, the pathologist-- a specialist trained to examine tissues and cells-- recognizes different structural patterns of cancer cell growth and calls these by different names. Some of these patterns are more aggressive than others, and it is important to identify them because they help predict the future behavior of the cancer, also called the prognosis. The pathologist describes many characteristics of the tumor: its overall size, the pattern and features of the cancer cells, the extent of their deviation from "normal" and the extent of invasion.

The pathologist also examines the axillary lymph nodes to determine whether they contain cancer cells. These findings provide the most important information to predict prognosis. Other tests may be useful for diagnosis, selection of treatment, or for prognosis-- for example, estrogen and progesterone receptor assays, DNA and S phase analysis, flow cytometry, and search for tumor oncogenes. They are utilized in all cases of breast cancer, and the results are included in the pathologist's final report. Your doctor will be able to explain to you the significance of these tests as they pertain to you.

Other Types of Breast Cancer

Although there are other types of breast cancer than those described above, they are not common and will not be dealt with at length in this guide. Some examples are Paget's Disease, a cancerous growth that first appears as scaling of the nipple, and inflammatory cancer, a rare and relatively fast-growing cancer that causes redness and swelling of the breast, and may not form a distinct mass.

Distinctions such as medullary, mucinous, tubular, and papillary generally refer to characteristics of ductal carcinoma and are best explained by a physician when applicable to an individual patient.

Spreading and Metastases

The danger of breast cancer is its ability to spread to the lymph nodes under the arms or to other parts of the body. Lymph nodes are a series of glands that are linked throughout the body (the lymphatic system), which drain waste from the blood and secrete important components of the immune system into the blood stream. Lymph nodes located under the arm (axilla) are called axillary nodes, and the removal of these nodes is called an axillary dissection. When cancer spreads to the lymph nodes or to other parts of the body this is called metastasis.

The Stages of Breast Cancer

Stage is important in predicting the likelihood of distant spread or metastasis. Stage also influences treatment planning and determines prognosis. As stage of cancer increases, the risk of metastasis increases. Depending on your stage, your physician may advise various tests such as X-rays, bone scans, and/or CT scans to determine the presence or absence of measurable metastasis. Stage and presence of metastases will influence treatment. Staging of a breast cancer occurs after the surgical sample is examined by the pathologist. To make this process easier medical science has devised a system of staging called TNM (T = tumor, N = node, M = metastasis).

Stage In situ - Ductal Carcinoma In situ or Lobular Carcinoma In situ, or Paget's Disease of the nipple.

Stage 1 - The tumor is equal to or smaller than 2 centimeters. There are no axillary lymph nodes positive for cancer, and there is no evidence of distant metastasis.

Stage 2 - The tumor is over 2 centimeters but not more than 5 centimeters in size. The axillary lymph nodes may or may not be positive for cancer. If a tumor is smaller than 2 centimeters, but the lymph nodes are positive, this would also be considered Stage 2.

Stage 3 - The tumor is larger than 5 centimeters with axillary lymph nodes positive for cancer. It may extend into the pectoral muscle. In Stage 3, there is no distant metastasis.

Stage 4 - If distant metastasis to other organs has occurred, the cancer is considered in this stage regardless of the size of the tumor or the number of nodes involved.

The TNM system breaks down Stages 2 and 3 even further, but such distinctions are not necessary for a basic understanding of breast cancer staging. Early stage breast cancer includes stages In situ, Stage 1, and Stage 2.