Anastrozole Compared With Tamoxifen For Advanced Disease.(hormone-sensitive breast cancer)

2001 DEC 6 - (NewsRx.com & NewsRx.net) -- According to authors of a multicenter study, Arimidex (anastrozole) should be the first choice, first-line therapy for postmenopausal women with hormone-sensitive advanced breast cancer.

Conclusions were drawn from a study involving the largest patient population ever investigated that compared the two treatments in an advanced setting. The study program involved two randomized, double-blind, multicenter trials, one conducted in North America and Canada, and the second conducted in the rest of the world, which compared daily treatment with Arimidex 1 mg or tamoxifen 20 mg in postmenopausal women with hormone-sensitive or receptor-unknown tumors.

The data are the full analysis of the combined results of these two studies, which between them, involved over 1000 breast cancer patients. The results in patients who had confirmed hormone-sensitive tumors (60% of the study population and the target patients for this intervention), were very encouraging. A retrospective analysis of this patient subgroup revealed that Arimidex was significantly superior to tamoxifen in terms of median time to disease progression (TTP) (median 10.7 months vs. 6.4 months respectively, p=0.022).

The study was published in the October 19, 2001, issue of the journal Cancer.

The investigators explored a number of possible prognostic factors which could have contributed to the superior efficacy seen with Arimidex in these patients (age, prior treatment, presence/absence of visceral, liver or bone metastases) and concluded that only the hormone receptor status of the tumor had any significant impact on treatment difference. In light of this finding, the investigators believe that the benefits of Arimidex over tamoxifen may have been diluted in the results from the overall population by the high proportion of patients with tumors of unknown hormone receptor status included in the combined analysis (40%). The differing mechanisms of action of the two compounds could hold the key to the superiority of the Arimidex treatment.

The potential impact of these differences in terms of treatment side effects were also explored in the combined analysis. Both compounds were generally well tolerated and appeared similar in terms of number of side effects reported. However, a significantly lower incidence of thromboembolic events were observed in patients receiving Arimidex compared with ...