Friday, July 29, 2011 (Last Updated: 08/01/2011)
FRIDAY, July 29 (HealthDay News) -- Five years of tamoxifen is associated with 15 years of reduced breast cancer recurrence and mortality in estrogen receptor (ER)-positive disease, but it has no effect on ER-negative disease, according to a meta-analysis published online July 29 in The Lancet.
Christina Davies, B.M.B.Ch., from the Clinical Trial Service Unit in Oxford, U.K., and colleagues reviewed individual patient data from 20 trials relating the effects of tamoxifen on early breast cancer, to quantify hormone receptor levels, use of chemotherapy, and other factors. The study analyzed five years of tamoxifen usage versus no tamoxifen adjuvant therapy in 21,457 women with about an 80 percent compliance rate. Recurrence and death rate ratios (RRs) were evaluated by log-rank analyses.
The investigators found that five years of tamoxifen substantially reduced recurrence rates throughout the first 10 years in women with ER-positive disease (RR, 0.53, years zero to four; 0.68, years five to nine; and 0.97, years 10 to 14) and significantly reduced the rates in marginally ER-positive disease (RR, 0.67). The RR in ER-positive disease was approximately independent of age, progesterone receptor status or level, nodal status, and use of chemotherapy. A one-third reduction in breast cancer mortality was observed throughout the first 15 years. Tamoxifen had little effect on overall non-breast cancer mortality, with a small increase in thromboembolic and uterine cancer mortality in women older than 55 years, thereby reducing all-cause mortality substantially. Tamoxifen had little or no effect on breast cancer recurrence or mortality in ER-negative disease.
"Five years of adjuvant tamoxifen safely reduces 15-year risks of breast cancer recurrence and death. ER status was the only recorded factor importantly predictive of the proportional reductions," the authors write.
One study author disclosed financial ties to a pharmaceutical company.
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