Weekly Paclitaxel Superior to Less Frequent Dosing in Metastatic Breast Cancer
According to results presented at the 40th annual meeting of the American Society of Clinical Oncology (ASCO), treatment with paclitaxel (Taxol®) every week provides superior outcomes to treatment every 3 weeks with paclitaxel in women with metastatic breast cancer.
Metastatic breast cancer refers to cancer that has spread from the breast to distant and/or several sites in the body. Standard treatment for metastatic breast cancer consists of chemotherapy, either used as single agents or in combination with other agents. Paclitaxel is a commonly used chemotherapy agent in the treatment of metastatic breast cancer. Herceptin® (trastuzumab) is a monoclonal antibody that also may be used in the treatment of metastatic breast cancer. Herceptin® was designed to target and bind to specific areas on a cancer cell that overexpress the human epidermal growth factor receptor (HER2), referred to as HER2-positive breast cancer. The binding of Herceptin® stimulates the immune system to help kill the cancer cells and may have some direct killing effects on the cancer cell. Researchers continue to evaluate different scheduling and dosing of regimens to achieve optimal long-term survival in these patients.
Researchers from Memorial-Sloan Kettering Cancer Center (MSKCC) recently conducted a clinical trial to evaluate different schedules of paclitaxel with or without Herceptin® in patients with metastatic breast cancer. Data from this trial included approximately 700 patients, 580 of whom were directly involved in this trial, and 120 of whom had participated in the CALGB 9342 trial that utilized the same weekly paclitaxel regimen. All patients had received prior therapy and were treated with either paclitaxel every week or paclitaxel every 3 weeks. Patients who were HER2-positive were also treated with Herceptin®. Anti-cancer responses were achieved in 40% of patients treated with paclitaxel every week, compared to only 28% of patients treated every 3 weeks. Time to cancer progression was 9 months for patients treated with weekly paclitaxel, compared to 5 months for those treated with paclitaxel every 3 weeks. Overall survival was 24 months for patients treated with weekly paclitaxel, compared to only 16 months for those treated with paclitaxel every 3 weeks. Herceptin® did not improve outcomes in patients with HER2-negative breast cancer. Weekly paclitaxel was associated with more numbness and tingling of hands and feet, but with fewer abnormalities of blood cell levels.
The researchers concluded that weekly paclitaxel with or without Herceptin® should become adopted as a new standard dosing regimen for patients with metastatic breast cancer. Patients with metastatic breast cancer who are to be treated with paclitaxel may wish to speak with their physician regarding their individual risks and benefits of weekly paclitaxel.
Reference: Seidman D, Berry C, Cirrincione C, et al. CALGB 9840: Phase III study of weekly (W) paclitaxel (P) via 1-hour (h) infusion versus standard (s) 3h infusion every third week in the treatment of metastatic breast cancer (MBC), with trastuzumab (T) for HER2 positive MBC and randomized for T in HER2 normal MBC. Proceedings from the 40th annual meeting of the American Society of Clinical Oncology. New Orleans, LA. June 2004. Abstract #512.
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