Docetaxel is a well established chemotherapy agent in the treatment of primary breast cancer. Docetaxel is also used alone or as part of a combination regimen to treat secondary breast cancer or cancer that originated in the breast but has spread to other parts of the body such as the lungs, brain, liver and bones.
It was in August 2004, that the United States Food and Drugs Administration (US FDA) approved the use of docetaxel injection (available as Taxotere from Aventis Pharmaceuticals) as an adjuvant therapy. The therapy is to be given in combination with doxorubicin and cyclophosphamide to treat women with operable, node-positive breast cancer undergoing surgery for removal of a breast tumor. Node-positive breast cancer refers to a primary breast cancer that has spread to the nearby lymph nodes.
The approved dose of docetaxel in operable, node-positive breast cancer is 75 mg for each m2 of the body surface area. The body surface area is calculated based on the patient’s height and weight using nomograms or charts. The docetaxel injection is to be administered one hour after injections of doxorubicin and cyclophosphamide.
The recommended dose for doxorubicin is 50 mg/m2 and for cyclophosphamide, the dose is 500 mg/m2. The injections are given every three weeks for six cycles. The three week interval between the treatments allows a window of time for the body to recover from the cytotoxic effects of the therapy.
One trial of 1,491 women with node-positive, operable breast cancer showed that those who were treated with docetaxel 75 mg/m2 one hour after doxorubicin 50 mg/m2 and cyclophosphamide 500 mg/m2 (TAC arm) had a significantly longer disease-free survival than women who received doxorubicin 50 mg/m2 followed by fluorouracil 500 mg/m2 and cyclophosphamide 500 mg/m2 (FAC arm). After a median follow up period of 55 months, those in the TAC arm were 26% less likely to suffer a relapse than those in the FAC arm.
However, there was a higher incidence of side effects in the TAC versus FAC arm, with increased rates of anemia, mouth sores, amenorrhea, fever, allergic reactions and edema among the women who received TAC. A small fraction of patients also developed congestive heart failure and leukemia as a side effect of the TAC regimen, at 1.6% and 0.4% , respectively.