Treatment with aromatase inhibitors improves outcomes versus treatment with tamoxifen for patients with early-stage breast cancer, according to a report published by the German Institute for Quality and Efficiency in Health Care (IQWiG).
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Hormone therapy with tamoxifen alone, an aromatase inhibitor alone, or a combination of both is standard of care for the treatment of hormone receptor-positive breast cancer. The US Food and Drug Administration has granted approval for three drugs in the aromatase inhibitors drug class: anastrozole, exemestane, and letrozole.
The Federal Joint Committee commissioned IQWiG to investigate the effects of aromatase inhibitors’ on hormone receptor-positive breast cancer in comparison with other treatment options, notably the anti-estrogen tamoxifen. Researchers based their assessment on published studies and additional data or information provided by the drug manufacturers.
The evidence for early-stage breast cancer was better than for advanced disease: 12 of the 19 studies that IQWiG included in the assessment refer to early-stage breast cancer, and the number of participants were much higher in studies of early-stage breast cancer than in advanced breast cancer studies (approximately 39,000 vs 3000, respectively). No added benefit was determined for the three evaluated aromatase inhibitors over tamoxifen for patients with advanced breast cancer.
For patients with early-stage breast cancer, findings showed that aromatase inhibitors treatment offered an added benefit over tamoxifen for two of the five approved treatment regimens: upfront therapy (beginning drug treatment with an aromatase inhibitor) and switch therapy (beginning with 2-3 years of treatment with tamoxifen before switching to an aromatase inhibitor). Favorable outcomes for aromatase inhibitors over tamoxifen were shown in terms of overall survival, freedom of recurrence, and reduced incidence of certain adverse events.
No overall advantage was determined for treatment with aromatase inhibitors for extended therapy (beginning drug treatment with tamoxifen before switching to an aromatase inhibitor after 5 years); while freedom from recurrence was higher with this regimen, so were treatment discontinuations due to adverse events. The studies yielded no data concerning aromatase inhibitors for neoadjuvant therapy. Data were insufficient to determine any differences between the three aromatase inhibitors.
Jürgen Windeler, PhD, Director of IQWiG, commented in a press release that comparative assessments such as the report on aromatase inhibitors “can provide important information on benefit and harm and in this way help improve the quality of patient care.”
