Advanced Breast Cancer Patients Benefit More from Aromatase Inhibitors than Tamoxifen

Adapted from the NCI Cancer Bulletin.

Aromatase inhibitors (AIs) have proven superior to tamoxifen as a hormonal treatment for early-stage breast cancer in women with estrogen-sensitive tumors. The third generation of these agents - letrozole, anastrozole, and exemestane - is also widely used to treat advanced or metastatic breast cancer, though clinical results about their value in that setting have been mixed. Researchers from Greece analyzed published trials on this question and found that third-generation AIs provide a definite, if small, overall survival advantage.

"Our results may represent a departure from the standard management of advanced breast cancer with hormonal therapy that has been used for the last two decades," wrote Dr. John P.A. Ioannidis of the University of Ioannina School of Medicine and colleagues in the Sept. 20, 2006, Journal of the National Cancer Institute (see the journal abstract). "The standard of care may need to be reconsidered."

The AIs reduced the risk of death by 13 percent, which translates to about five months more life in women whose median survival is projected to be 40 months. Though they may produce more hot flashes, AIs are generally more tolerable than tamoxifen and also improve quality of life.

In an accompanying editorial, Drs. Catherine H. Van Poznak and Daniel F. Hayes of the University of Michigan agree that AIs are the drug of choice for women with endocrine-responsive metastatic breast cancer, without ruling out some use of tamoxifen. They cite surveys of oncology practice patterns which show that only about half of these women will receive AIs as adjuvant therapy, despite a recent recommendation by the American Society of Clinical Oncology.