Tests performed on tumor tissue

Tests performed on tumor tissue

If the pathologist's diagnosis is breast cancer, there are several tests that may be performed on the cancer cells. The results of these tests provide a prognosis and help the oncologist (cancer specialist) guide the patient’s treatment. The most useful of these are HER-2/neu and estrogen and progesterone receptors.

Her-2/neu is an oncogene . It codes for a receptor for a particular growth factor that causes cells to grow. Normal epithelial cells contain two copies of the Her-2/neu gene and produce low levels of the Her-2 protein on the surface of their cells. In about 20-30% of invasive breast cancers, the Her-2/neu gene is amplified and its protein is over-expressed. These tumors are susceptible to treatment that specifically binds to this over-expressed protein. The chemotherapeutic agent Herceptin (Tastuzumab) blocks the protein receptors, inhibiting continued replication and tumor growth. Patients with amplified Her-2/neu gene respond well to Herceptin and have a good prognosis.

Estrogen and progesterone receptor status are important prognostic markers in breast cancer. The higher the percentage of overall cells positive, as well as the greater the intensity, the better the prognosis. Estrogen and/or progesterone receptor positivity in breast cancer cells indicates sensitivity to hormones. The patient may be a good candidate for anti-hormone therapy.