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Key Words: breast cancer, chemotherapy, doxorubicin, paclitaxel, Taxol®. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary ².)

Women with early breast cancer who received the drug paclitaxel (Taxol) after standard chemotherapy did better than women treated with standard chemotherapy alone, researchers report in a study to be published in the March 15, 2003, issue of the Journal of Clinical Oncology and released early (Feb. 7, 2003) on the journal's Web site (see the journal abstract).

By contrast, patients who received higher than standard doses of the drug doxorubicin gained no benefit and experienced higher rates of side effects such as infection, anemia, and low blood counts.

The study involved 3,121 women with breast cancer that had spread to the lymph nodes. After surgery (either mastectomy or lumpectomy), all patients received additional therapy with the drug cyclophosphamide. All were randomly assigned to receive a standard dose of doxorubicin or one of two higher doses. Patients were also assigned at random to receive either Taxol or no further treatment after completing therapy with cyclophosphamide and doxorubicin.

Taxol: more women disease-free

After five years, 70 percent of the women who received Taxol were alive and disease-free, compared with 65 percent of the women who got no further treatment. Overall survival was 80 percent in the Taxol group and 77 percent in the group treated with standard chemotherapy alone.

Women treated with Taxol were 17 percent less likely to have a recurrence of breast cancer and 18 percent less likely to die than women not treated with Taxol, the researchers concluded. The multicenter study team was led by I. Craig Henderson, M.D., of the University of California at San Francisco.

More doxorubicin: no effect

Higher doses of doxorubicin had no effect on either survival without disease recurrence or overall survival. However, women who received the higher doses were more prone to develop infections, suffered more severely from anemia and low blood counts, and were hospitalized more frequently than women treated with the standard dose.

“The results of this study suggest that some patients with early breast cancer that has spread to the lymph nodes will benefit from the addition of Taxol to standard chemotherapy but not from higher doses of doxorubicin,” said Jeff Abrams, M.D., of the NCI’s Cancer Therapy and Evaluation Program.

Secondary analysis

A secondary analysis of particular relevance was performed in this study. This analysis separated patients into two groups according to whether or not their tumors expressed the receptor for the hormone estrogen.

Women whose tumors lacked estrogen receptors had significant benefit from the addition of Taxol; those whose tumors had estrogen receptors did not. (Most of the latter group of women also received the drug tamoxifen, which works against the effects of estrogen on the cancer cells.)

According to Abrams, this finding will require further confirmation in other Taxol studies before it can be determined if the addition of Taxol should be restricted to patients whose tumors lack the estrogen receptor.

Glossary Terms

Treatment with drugs that kill cancer cells.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer. It is also used to treat some types of kidney disease in children. Cyclophosphamide attaches to DNA in cells and may kill cancer cells. It is a type of alkylating agent. Also called CTX and Cytoxan.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer. Doxorubicin comes from the bacterium Streptomyces peucetius. It damages DNA and may kill cancer cells. It is a type of anthracycline antitumor antibiotic. Also called Adriamycin PFS, Adriamycin RDF, doxorubicin hydrochloride, hydroxydaunorubicin, and Rubex.

A type of hormone made by the body that helps develop and maintain female sex characteristics and the growth of long bones. Estrogens can also be made in the laboratory. They may be used as a type of birth control and to treat symptoms of menopause, menstrual disorders, osteoporosis, and other conditions.

A cell protein that binds a specific hormone. The hormone receptor may be on the surface of the cell or inside the cell. Many changes take place in a cell after a hormone binds to its receptor.

Surgery to remove abnormal tissue or cancer from the breast and a small amount of normal tissue around it. It is a type of breast-sparing surgery.

Surgery to remove the breast (or as much of the breast tissue as possible).

A drug used to treat breast cancer, ovarian cancer, and AIDS-related Kaposi sarcoma. It is also used together with another drug to treat non-small cell lung cancer. Paclitaxel is also being studied in the treatment of other types of cancer. It blocks cell growth by stopping cell division and may kill cancer cells. It is a type of antimitotic agent. Also called Taxol.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.