According to an article recently published in the *Journal of the American Medical Association,*chemotherapy for early breast cancer provides greater benefit for estrogen-receptor negative patients than for those with estrogen-receptor positive cancer. However, chemotherapy still provides a survival benefit for both groups of patients.
The majority of patients diagnosed with breast cancer have estrogen-receptor positive (ER-positive) breast cancer. This refers to cancer that is stimulated to grow from exposure to the female hormones estrogen and/or progesterone.
A component of therapy for patients with ER-positive breast cancer often includes hormone therapy, which slows or prevents spread of cancer cells by reducing their exposure to estrogen and/or progesterone.
Patients with ER-positive breast cancer often receive chemotherapy in addition to hormone therapy to further reduce their risk of recurrences and to improve their outcomes. However, the side effects of chemotherapy must be weighed against its benefits.
Estrogen-receptor negative (ER-negative) breast cancer refers to cancer that is not simulated to grow from exposure to estrogen and/or progesterone. Hormone therapy has not demonstrated an improvement in outcomes for this group of patients. Chemotherapy thus remains an important component of treatment for women with ER-negative breast cancer.
Researchers from the MD Anderson Cancer Center recently analyzed data from three large clinical trials in an attempt to define benefits of chemotherapy among women with early breast cancer who were either ER-positive or ER-negative.
The data reviewed was from trials conducted between 1985 and 1999 and included 6,633 women. The trials were conducted to compare outcomes among women with breast cancer that had spread to their axillary lymph nodes (node-positive), but not to other sites in the body. Some participants were treated with chemotherapy, and others were not.
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All patients benefited from chemotherapy; however, ER-negative patients had the greatest benefit:
- Overall mortality rates were improved by 55% among ER-negative patients with the use of chemotherapy compared with only 23% among ER-positive patients.
- There was nearly a 23% improvement of cancer-free survival at 5 years among ER-negative patients who were treated with chemotherapy over those who did not receive chemotherapy.
- There was a 7% improvement in cancer-free survival at 5 years among ER-positive patients who were treated with chemotherapy compared to those who did not receive chemotherapy.
- The chemotherapy combination of Adriamycin® (doxorubicin) and Cytoxan® (cyclophosphamide) plus Taxol® (paclitaxel) lowered the rate of a cancer recurrence by more than 50% when compared with low-dose cyclophosphamide, doxorubicin, and fluorouracil in patients with ER-negative cancers.
The researchers concluded that the use of chemotherapy in women with ER-negative, node-positive breast cancer significantly improves outcomes, including overall survival, cancer-free survival, and cancer recurrences in this group of patients. Although chemotherapy provides improved outcomes for patients with ER-positive, node-positive breast cancer, the improvements are not as pronounced as with those of ER-negative patients.
It is important for all patients with breast cancer to discuss their individual risks and benefits of treatment with chemotherapy with their physician.
Reference: Berry D, Cirrincione C, Henderson C, et al. Estrogen-Receptor Status and Outcomes of Modern Chemotherapy for Patients with Node-Positive Breast Cancer. Journal of the American Medical Association. 2006;295:1658-1667.
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