Abbott Molecular Inc.: Types of Breast Cancer

Breast cancer is not just one disease, but rather is a general term used to describe a number of different types of cancers which occur in the breast. Each different type of breast cancer behaves differently and has a different prognosis. Before describing the different cancers and how they are treated, some background information may be helpful.

The breast is an organ of the body designed to produce milk. The breast contains glands called lobules which produce breast milk. There are also tubes or channels called ducts which transport the milk from the glands to the nipple. The majority of breast cancers begins in either the ducts or the lobules and cancer names are based on their site of origin (i.e., ductal carcinoma of the breast or lobular carcinoma of the breast). The lobules and ducts are supported in the breast by surrounding fatty tissue and ligaments. There are also blood vessels and lymphatics present in the breast. Lymphatics are small thin channels similar to blood vessels. They do not carry blood, but collect and carry tissue fluid. This fluid ultimately re-enters the blood stream. Breast tissue fluid drains through the lymphatics into the axillary lymph nodes, located in the underarm. Lymph nodes are small glands through which lymphatic channels enter. They filter the lymph fluid and can serve as a barrier to the further spread of bacteria or cancer cells that may have entered the lymph fluid. Lymph nodes are not completely effective in filtering out cancer cells and may spread to other parts of the body despite their presence. Once cancer cells have gained access to either the lymph channels or the blood stream, they have the potential to spread to any area of the body. In breast cancer, these areas are typically the bone, the lungs, the liver and the brain.

Breast cancer is also categorized as invasive (infiltrating) or non-invasive (in-situ). Invasiveness, as it relates to cancer, refers to the cancer's ability to spread to other parts of the body (metastasize). If a cancer is invasive, it has the capability of growing directly into other parts of the body, or traveling in the blood or lymph fluid to these areas. Non-invasive cancers (in situ cancers) are those cancers which are defined by microscopic criteria as lacking the ability to spread to other parts of the body.

What are the types of breast cancers?
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.

For In Vitro Diagnostic Use.

Intended Use
The PathVysion HER-2 DNA Probe Kit (PathVysion Kit) is designed to detect amplification of the HER-2/neu gene via fluorescence in situ hybridization (FISH) in formalin-fixed, paraffin-embedded human breast cancer tissue specimens. Results from the PathVysion Kit are intended for use as an adjunct to existing clinical and pathologic information currently used as prognostic factors in stage II, node-positive breast cancer patients. The PathVysion Kit is further indicated as an aid to predict disease-free and overall survival in patients with stage II, node positive breast cancer treated with adjuvant cyclophosphamide, doxorubicin and 5-fluorouracil (CAF) chemotherapy.

The PathVysion Kit is indicated as an aid in the assessment of patients for whom HERCEPTIN (Trastuzumab) treatment is being considered (see HERCEPTIN package insert).

Warning:
Note: All of the patients in the Herceptin^® clinical trials were selected using an investigational immunohistochemical assay. The PathVysion assay was compared to the CTA on a subset of clinical trial samples and found to provide acceptably concordant results. The actual correlation of the PathVysion assay to Herceptin clinical outcomes in prospective clinical trials has not been established.

The Vysis PathVysion Kit is not intended for use to screen for or diagnose breast cancer. It is intended to be used as an adjunct to other prognostic factors currently used to predict disease-free and overall survival in stage II, node-positive breast cancer patients. In making decisions regarding adjuvant CAF treatment, all other available clinical information should also be taken into consideration, such as tumor size, number of involved lymph nodes, and steroid receptor status. No treatment decision for stage II, node-positive breast cancer patients should be based on HER-2/neu gene amplification status alone. The potential risks associated with misuse of the assay, or misinterpretation of the test results would be to assign patients to receive an adjuvant therapy regimen which is either too low for optimum effectiveness, or higher than necessary, potentially exposing the patient to serious side effects and, in rare cases, death. Selected patients with breast cancers shown to lack amplification of HER-2/neu, may still benefit from CAF adjuvant therapy on the basis of other prognostic factors which predict poor outcome. Conversely, selected patients with breast cancers shown to contain gene amplification may not be candidates for CAF therapy because of pre-existing or intercurrent medical illnesses. The dose and schedule of cyclophosphamide, doxorubicin, and 5-fluorouracil in the CAF regimen have not been standardized. Vysis will provide training in specimen preparation, assay procedure, and interpretation of FISH testing of the Her-2 gene for inexperienced users.