Older chemotherapy regimens improved survival of ER-poor breast cancer

January 3, 2008

NEW YORK (Reuters Health) - A meta-analysis of trial data indicates that adjuvant chemotherapy regimens used in the 1970s and 1980s safely improved the long-term survival of estrogen receptor (ER)-poor breast cancer. The authors believe that current and future chemotherapy regimens are likely to yield even greater improvements in survival.

"This latest update from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) further confirms the contribution of chemotherapy to the decreasing recurrence of oestrogen-receptor-negative breast cancer," Dr. Rinat Yerushalmi and Dr. Karen Gelmon, from the British Columbia Cancer Agency in Vancouver, comment in a related editorial.

As reported in The Lancet for January 5, Dr. Richard Peto, from the University of Oxford in the UK, and colleagues analyzed data on roughly 6000 women with ER-poor breast cancer enrolled in 46 trials comparing adjuvant polychemotherapy with no chemotherapy and from about 14,000 women enrolled in 50 trials comparing tamoxifen with no tamoxifen.

The polychemotherapy regimens were used in trials starting between 1975 and 1996 (median 1984), were non-taxane based, and typically involved six cycles.

In the tamoxifen trials, which started between 1972 and 1993 (median 1982), the drug was given with and without polychemotherapy depending on the study.

Treatment with polychemotherapy 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 polychemotherapy were 33% and 45%, respectively (p < 0.00001). The corresponding breast cancer mortality rates were 24% and 32% (p = 0.0002).

The polychemotherapy 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 ER-poor disease. Moreover, no significant interaction was noted between tamoxifen and polychemotherapy.

"Efforts should now be directed towards the establishment of finer definitions of subtypes of (ER-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," Dr. Yerushalmi and Dr. Gelmon conclude.