Aromatase Inhibitors in Breast Cancer: An Update

Diana E. Lake, MD, Clifford Hudis, MD


Cancer Control. 2002;9(6) 

In This Article


One of the endpoints of the ATAC trial -- new invasive breast cancer incidence -- suggests that prevention strategies with the aromatase inhibitors warrant investigation. In the ATAC trial, anastrozole compared with tamoxifen was associated with a 58% reduction in the incidence of contralateral invasive breast cancer.[25] Three ongoing pilot programs are testing this preventive role ( Table 1 ).[28,29,30]

The Royal Marsden Hospital[28] is conducting a study of 29 postmenopausal, healthy women treated with letrozole. Study parameters include breast cell proliferation, bone density, and lipid metabolism. Increase in bone resorption was documented after 3 months of treatment with letrozole.

Memorial Sloan-Kettering Cancer Center[29] has an ongoing clinical trial for postmenopausal women with stage 0 to III breast cancer who have had no prior anti-estrogen therapy. Hence, most of these patients are ER-. They are being treated with a combination of the aromatase inhibitor exemestane and the SERM raloxifene. The endpoints are bone and lipid changes and second breast cancer incidence. The correlative science component to this study is breast cell proliferation. This group of 30 planned patients was targeted for endocrine therapy as a pilot study only. The investigator is aware that most hormone receptor-positive patients are treated with tamoxifen in the adjuvant setting. However, with endpoints of bone density, lipid profile changes, and breast cell proliferation, hormone receptor-negative patients may clearly be studied. The issues addressed by this pilot study are somewhat different from those in the ATAC trial, where the combination arm, consisting of tamoxifen and anastrozole, demonstrated no improvement over tamoxifen alone.

The ApreS group (Aromasin Prevention Study)[30] is a randomized trial for women with BRCA1/BRCA2 mutations. The anticipated number of patients to accrue is 666. These patients will be treated with either exemestane or placebo.

In addition, the NSABP B-35 study randomizes patients with breast-conserving therapy to treatment with either tamoxifen or anastrozole.


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