Types of Breast Cancer

Question and Answer with Ralph Maeda, M.D.
What are the types of breast cancers?
Dr. Maeda:
Breast cancer is not just one disease, but rather is a general term used to describe a number of different types of cancers that occur in the breast. The majority of breast cancers can be classified into one of the following categories; infiltrating ductal carcinoma, infiltrating lobular carcinoma, ductal carcinoma in situ, lobular carcinoma in situ, inflammatory carcinoma, Paget's disease, and cystosarcoma phyllodes. There are other tumors of the breast, such as angiosarcoma, squamous cell cancer and lymphoma, but they are quite rare. These categories are based on the microscopic appearance of the breast tissue obtained with a biopsy sample.

Infiltrating Ductal Carcinoma

Infiltrating Ductal Carcinoma begins in the cells forming the ducts of the breast. It is the most common form of breast cancer, comprising about 65-85% of all cases. On a mammogram, invasive ductal carcinoma is usually found as an irregular mass, or as a group of small white irregular dots called microcalcifications, or a combination of both. It may also appear as a lump in the breast. On physical examination, this lump usually feels much harder or firmer than other benign causes of lumps in the breast.

Infiltrating Lobular Carcinoma

Infiltrating Lobular Carcinoma comprises 5 to 10 percent of breast cancers. This type of breast cancer can appear similar to infiltrating ductal carcinoma on mammography, but on examination of the breast there is usually not a hard mass, but rather a vague thickening of the breast tissue. Lobular carcinoma can occur in more than one site in the breast (multicentric) or in both breasts simultaneously (bilateral).

Ductal Carcinoma In Situ (DCIS)

Ductal Carcinoma In Situ (DCIS) is a pre-invasive form of breast cancer. It is commonly seen in association with an invasive breast cancer. If it occurs without an invasive cancer there is usually no lump associated with it. On mammography, there may be fine microcalcifications which can signal its presence. DCIS is frequently multifocal, meaning it is located in more than one area of the breast. Approximately one-third of DCIS cases are multifocal. If DCIS is treated with biopsy alone, about 40% of women will ultimately develop an invasive cancer of that breast in the future.

Lobular Carcinoma In Situ (LCIS)

Lobular Carcinoma In Situ (LCIS) is usually encountered as an incidental finding in a breast biopsy. It has no symptoms, and has no characteristic pattern on mammography. It has been found to occur in multiple sites in the same breast in 40 to 90% of cases. In 50% of the cases, it may also occur in the opposite breast. The risk of developing an invasive cancer of the breast with LCIS is approximately 1% per year. The invasive cancer that develops has about an equal chance of being in either breast regardless as to which breast the LCIS was initially found. A large percentage (38%) of women with LCIS may not develop an invasive cancer until more than 20 years after the initial diagnosis.

Inflammatory Carcinoma

Inflammatory carcinoma of the breast is a subtype of infiltrating ductal carcinoma, but is named for its typical clinical presentation. The breast becomes red, swollen, and warm, and the skin becomes quite thickened. The breast appears as if it were infected. This appearance is due to the rapid growth of the cancer which blocks the lymphatics in the breast, causing it to swell and appear infected. The cancer has already spread to the lymph nodes in 90% of the cases at the time of diagnosis. The prognosis for this cancer is very poor, and is fortunately relatively uncommon.

Paget's Disease

Paget's disease of the breast accounts for about one to four percent of all breast cancers. It occurs typically as a crusting and scaling of the nipple. It can be mistaken for a benign skin condition unless there is a high index of suspicion.

Cystosarcoma Phyllodes

Cystosarcoma Phyllodes is a firm tumor that resembles a benign fibroadenoma. This cancer is very different than other cancers of the breast. It seldom spreads to the lymph nodes, but can metastasize to other parts of the body by way of the bloodstream.

For more in-depth information about breast cancer, please read the Breast Cancer article.


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