NEW YORK (Reuters Health) - A review of published clinical trials indicates that adjuvant chemotherapy regimens - drug therapy administered after surgical removal of the cancer -- used in the 1970s and 1980s safely improved the long-term survival of women with breast cancers associated with poor outcomes.
The authors of the report, published in The Lancet, believe that current and future chemotherapy regimens are likely to yield even greater improvements in survival for women with estrogen-negative breast cancer. This type of breast tumor does not respond to treatment as well as estrogen-positive tumors do.
"This latest update from the Early Breast Cancer Trialists' Collaborative Group further confirms the contribution of chemotherapy to the decreasing recurrence of estrogen receptor-negative breast cancer," Dr. Rinat Yerushalmi and Dr. Karen Gelmon, from the British Columbia Cancer Agency in Vancouver, comment in a related editorial
Dr. Richard Peto, from the University of Oxford in the UK, and colleagues analyzed data on roughly 6,000 women with estrogen receptor-poor breast cancer enrolled in 46 trials comparing adjuvant chemotherapy with no chemotherapy and from about 14,000 women enrolled in 50 trials comparing tamoxifen with no tamoxifen.
The chemotherapy regimens were used in trials starting between 1975 and 1996, were not based on taxane and typically involved six cycles. Taxanes are a class of drugs found to be very effective for breast cancer, but drugs in this class were not approved for use by the United States FDA until the 1990s. In the tamoxifen trials, which started between 1972 and 1993, the drug was given with or without chemotherapy depending on the study.
Treatment with chemotherapy was associated with significant reductions in breast cancer recurrence and mortality in women younger than 70 years of age at trial entry. For instance, in women younger than 50 years, the 10-year risks of recurrence with and without chemotherapy were 33 percent and 45 percent, a significant difference. The corresponding breast cancer mortality rates were 24 percent and 32 percent.
The chemotherapy regimens were also deemed safe, as no increase in all-cause mortality was seen with their use.
Tamoxifen, by contrast, had little effect on breast cancer recurrence or mortality in women with estrogen receptor-poor disease. Moreover, no significant interaction was noted between tamoxifen and chemotherapy.
"Efforts should now be directed towards the establishment of finer definitions of subtypes of (estrogen-receptor negative) breast cancers, the study of less debilitating but active regimens and the development of new strategies for those who are not cured by conventional chemotherapy," Yerushalmi and Gelmon conclude.
SOURCE: The Lancet, January 5, 2007.
Reuters Health
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