HOLLYWOOD, FloridaThe 2002 National Comprehensive Cancer Network (NCCN) breast cancer treatment guidelines include a number of important updates regarding the use of aromatase inhibitors, leuteinizing hormone-releasing hormone (LHRH) agonists, and sentinel lymph node biopsy. Robert W. Carlson, MD, chair of the NCCN Breast Cancer Panel, presented the guidelines at the Seventh Annual NCCN Conference.
Based on results of the large, randomized Arimidex, Tamoxifen(Drug information on tamoxifen) Alone or in Combination (ATAC) trial, the panel elected to add a footnote to the guidelines for systemic adjuvant therapy of hormone-receptor-positive postmenopausal women with node-negative stage I-IIB disease (larger than 1 cm).
The footnote states that the selective aromatase inhibitor anastrozole(Drug information on anastrozole) (Arimidex) is an option to tamoxifen (Nolvadex) in this setting, pending further long-term evidence of anastrozole’s efficacy and safety.
ATAC showed a 17% reduction in risk of recurrence with the use of anastrozole (22% reduction in hormone-sensitive patients). The footnote states that "at the current time, anastrozole can be considered an option to tamoxifen after discussion of available data between physician and patient. These data do not address whether women currently on tamoxifen should be changed to anastrozole. Anastrozole is not appropriate for premenopausal women."
"The reason that we have left the two drugs as equivalent," said Dr. Carlson, professor of medicine and medical informatics, Stanford University, "is that we have 25 years of experience with tamoxifen. The aromatase inhibitors have been licensed since 1995 (anastrozole) and 1996 (letrozole [Femara]), so we don’t have long-term data on toxicities."
In the ATAC trial, anastrozole was also superior in reducing the incidence of contralateral breast cancers, with a 58% reduction. "This is a relatively remarkable result," Dr. Carlson said, "and it will be really important if it holds up, because we already know from the Breast Cancer Prevention Trial that tamoxifen reduces the risk of contralateral breast cancer by 50%. If we’re now seeing an additional 58% reduction, that’s an enormous risk reduction that could potentially be moved into the breast cancer prevention setting."
The new guidelines also upgraded the use of anastrozole and letrozole(Drug information on letrozole) as equal to tamoxifen as first-line therapy for postmenopausal women with hormone-responsive recurrent breast cancer and no prior hormonal therapy. Dr. Carlson referred to two randomized trials of anastrozole vs tamoxifen in this setting that included more than 1,000 patients (J Clin Oncol 18:3748, 3758, 2000). The studies showed equivalence or superiority to tamoxifen in time to progression.