Thursday, December 9, 2004

ARIMIDEX SHOULD BE PREFERRED FIRST-LINE THERAPY IN POSTMENOPAUSAL, LOCALIZED, HORMONE-RECEPTOR-POSITIVE BREAST CANCER

AstraZeneca Plc's aromatase pharmaceutical brand inhibitor Arimidex (anastrozole) is superior to tamoxifen for the treatment of postmenopausal women with localized, hormone-receptor-positive breast cancer, and a five-year course of the drug should be considered the preferred initial adjuvant endocrine therapy for these patients, researchers reported.

The Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial investigators randomly assigned 9,366 patients to receive Arimidex, tamoxifen or a combination of the two for five years. The study authors noted that five years of tamoxifen therapy is currently considered the standard adjuvant endocrine treatment for postmenopausal women with localized, hormone-receptor-positive breast cancer. The combination-treatment arm of the study was discontinued after interim analyses indicated the regimen had low efficacy.

At 68 months--8 months beyond the conclusion of the planned five-year treatment period--data showed Arimidex-treated patients had significantly better disease-free survival than tamoxifen-treated subjects, with 575 events in the Arimidex group and 651 in the tamoxifen group. Time to recurrence was also significantly improved with Arimidex, with 402 events in the Arimidex group and 498 in the tamoxifen group.

Arimidex also significantly reduced the incidence of distant metastases (324 vs. 375 patients) and contralateral breast cancer (35 vs. 59 patients; 42 percent reduction) as compared with tamoxifen.

Additionally, treatment with Arimidex was associated with significantly fewer incidences of endometrial cancer, thromboembolic events, ischemic cerebrovascular events, vaginal bleeding, hot flushes and vaginal discharge. Tamoxifen-treated patients were less likely to experience fractures and arthralgia.

Arimidex was associated with a 12 percent reduction in deaths from breast cancer, which was not statistically significant. The authors, however, said that since the study sample had a relatively good prognosis, it is too early to expect a significant difference in survival.

"The present data suggest that it is not appropriate to wait five years to start an aromatase inhibitor," the study authors concluded. "Furthermore, the higher rates of recurrence (especially in years one through three), and the increased numbers of adverse events and treatment withdrawals associated with tamoxifen, lend support to the approach of offering the most effective and well tolerated therapy at the earliest opportunity.

"Five years of [Arimidex] should now be considered as the preferred initial adjuvant endocrine treatment for postmenopausal women with hormone-receptor-positive localized breast cancer."

The study can be found on the Web site of The Lancet.