ASCOAlthough aromatase inhibitors show promise for preventing recurrence
following surgery in women with hormone-receptor-positive breast cancer,
tamoxifen (Nolvadex) remains the standard of care, according to an
evidence-based technology assessment of the aromatase inhibitors, sponsored by
the American Society of Clinical Oncology. The ASCO expert panel found that the
available data on aromatase inhibitors for this indication do not support
routine use outside of clinical trials.
"While recent findings on aromatase inhibitors are encouraging, data on
long-term use of the drugs are needed before a change in the standard of care
is justified," Eric Winer, MD, of Dana-Farber Cancer Institute and chair
of the panel, said at a press briefing at the 38th Annual ASCO Meeting.
The panel assessed the medical literature and the preliminary findings from
the ATAC study (Arimidex, Tamoxifen Alone or in Combination) presented last
year at the San Antonio Breast Cancer Symposium. ATAC showed that the aromatase
inhibitor anastrozole (Arimidex) may be more effective than tam-oxifen at
preventing recurrence in postmenopausal early-stage breast cancer patients
after surgery. Median follow-up on the ATAC trial is currently 33 months.
The panel concluded that because a 5-year course of therapy is required for
tamoxifen to provide its greatest clinical benefit, the data on anastrozole are
not sufficiently long-term to appropriately compare the two drugs. It is also
possible, they said, that long-term use of anastrozole may lead to unexpected
side effects. In contrast, there is extensive long-term follow-up data on
patients treated with tamoxifen and a clearer understanding of its associated