Types of Breast Cancer / Pathology

Pathologists confirm a suspected cancer diagnosis by examining tissue removed either during surgery or in less invasive biopsy procedures.

For more information about pathology, see Pathology and Cancer. For more information about biopsies, see Cancer Diagnosis.

Infiltrating Ductal Carcinoma

This most common type of breast cancer represents approximately 80 percent of all diagnoses. Infiltrating or invasive means the cancer cells have left the lining of the ducts and are forming a tumor outside the duct. The cells often form a tough scar-like shell that is palpable on examination and visible on mammography.

Infrequently, men develop this type of breast cancer. Approximately 1,700 males are diagnosed annually in the United States and receive the same treatment as women.

Treatment requires surgical removal of the tumor with a lumpectomy involving less than 25 percent of the entire breast tissue, or a mastectomy to remove the entire breast. Some lymph nodes are usually removed from the armpit during surgery and tested for cancer. The surgeon recommends a procedure based on the size of the lump and other factors.

Chemotherapy, radiation and hormonal therapy are considerations following surgery. These treatments are determined by the patient and the cancer care team, based on the final pathology report.

Lobular Carcinoma

About 12 percent of breast cancers start in lobules located at the end of each duct. Lobules are small grape-like clusters (about 12 to 15 clusters in each breast) that produce milk.

Lobular carcinoma is either "infiltrating or invasive" or "in-situ." In situ is usually pre-cancerous and represents a marker of an increased risk for later malignancy. Infiltrating lobular carcinoma, however, is cancerous. Patients often describe a "thickening" of breast tissue (not a hard lump formed from scar tissue) as cancerous cells grow as small finger-like projections.

Because a lump usually does not exist, these cancers sometimes grow larger than ductal carcinomas before they are detected.

Ductal Carcinoma in Situ (DCIS)

Accounting for approximately 10 percent of all breast cancers, Ductal Carcinoma In Situ (DCIS) is a highly curable early stage breast cancer. DCIS is located entirely within the milk ducts of the breast. It does not penetrate the duct walls or surrounding areas.

On a mammogram, these tumors most often appear as microcalcifications representing tiny specks of calcium clustered in the breast. They usually cannot be felt on physical exam as a lump.

The pathology report will have the terms noncomedo and the more serious comedo, which means the cells filling the duct appear more aggressive.

Inflammatory Breast Carcinoma

Accounting for only 1-4 percent of all breast cancers, the diagnosis of inflammatory breast cancer is a source of great concern. The term inflammatory refers to the appearance of the breast – red, swollen and warm to the touch. Initially patients are often treated with antibiotics for an infection. If the condition does not improve after two weeks of antibiotics, a biopsy is performed to check for inflammatory breast carcinoma.

Because this is an aggressive breast cancer, the first treatment is often high-dose chemotherapy. This is called neoadjuvent treatment because it is administered before surgery to help shrink the tumor. Following chemotherapy, a mastectomy is performed. Some medical oncologists administer eight cycles of chemotherapy before surgery; others give four doses, then surgery, then four more cycles of chemotherapy.

Paget's Disease of the Breast

Paget's disease of the breast is characterized by itching and scaling around the nipple. It is sometimes mistaken for eczema of the nipple. A mammogram is performed to detect cancer in the breast. Then a biopsy is performed on the skin of the nipple.

There are two kinds of Paget's disease. One only involves the nipple. Treatment entails surgically removing the nipple and areola (dark skin around the nipple). Plastic surgeons can reconstruct the nipple. The second type includes invasive cancer that has spread from the nipple. If the area is far away from the nipple, a mastectomy is done. If the area is close to the nipple, a wide excision followed by radiation therapy is an option.

Lobular Carcinoma in Situ (LCIS)

Lobular Carcinoma In Situ (LCIS) involves the milk-producing lobules. LCIS is considered a pre-cancerous condition, although it can develop into cancer in about 25 percent of women. LCIS does not show up on mammogram.

LCIS is considered a marker that cancer may develop later. Treatment for LCIS is controversial and must be discussed with an oncologist or surgeon.