The analysis calculated the hazard ratio of death from breast cancer as 0.88 for anastrozole in comparison with tamoxifen.
In both groups, the women who died of breast cancer tended to be younger, with a median age 68 years vs. 74 years for those who died of other causes.
“There are a lot more women free of cancer down the line,” Dr. Buzdar said, adding that the fact that they are dying older and of other causes “means we can prevent cancer in a much larger population, and they are having a normal life span.”
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Expert Panel Eyes Inhibitor Issues
The International Aromatase Inhibitor Expert Panel of 24 breast cancer experts reviewed the major randomized trials of adjuvant treatment and concluded that aromatase inhibitors are superior to tamoxifen, whether given as an initial hormonal therapy or sequentially in patients who started on tamoxifen (Curr. Med. Res. Opin. 2006;22:1575–85). The panel also found, however, that the best way to use aromatase inhibitors is yet to be determined.
Among the issues addressed by the panel, which was supported by an unrestricted grant from AstraZeneca, are:
▸ Patient populations. Patients who were switched to aromatase inhibitors after they did not recur while on tamoxifen are not the same as patients who were randomized to a sequence of tamoxifen followed by an aromatase inhibitor. “Switching-study patient populations are by default enriched with patients who respond well to endocrine therapy by excluding patients who have had an early recurrence despite tamoxifen treatment,” the panel wrote.
▸ No direct comparisons. Until the Breast International Group-98 trial publishes mature data comparing 5 years of letrozole therapy with sequence therapy, no data are available from trials comparing a sequential strategy with monotherapy. For now, the panel found that the best researchers can do is to construct models based on existing data.
▸ Duration of therapy. Although the optimal duration of tamoxifen therapy is 5 years, and 5 years has been adopted as the standard for endocrine therapy, the optimal duration of aromatase inhibition is not known.
▸ Cardiac, stroke, and endometrial cancer risk. Data on patients with preexisting coronary heart disease are not available for tamoxifen or aromatase inhibitors, according to the panel. Although there is no evidence that these patients should be excluded from treatment with aromatase inhibitors, this needs to be studied.