Breast Cancer Coverage from Every Angle

Extending Aromatase Inhibitor Therapy in Breast Cancer

By: Sarah Campen, PharmD
Posted: Monday, January 21, 2019

In women with breast cancer, treatment with tamoxifen and/or an aromatase inhibitor for 5 years is effective in reducing the risk of recurrence, but a substantial risk remains after treatment discontinuation. The initial results of a study presented at the 2018 San Antonio Breast Cancer Symposium (SABCS; Abstract GS3-03) found that continuing treatment with an aromatase inhibitor beyond 5 years may decrease disease recurrence and death from breast cancer.

“This meta-analysis will provide the most reliable possible summary of the available evidence to inform clinicians,” stated Richard Gray, MSc, of the Early Breast Cancer Trialists’ Collaborative Group at the University of Oxford, United Kingdom, and colleagues.

The Early Breast Cancer Trialists’ Collaborative Group study, which included 24,912 women from 12 randomized trials, compared 3 to 5 years of aromatase inhibitor versus no further treatment after 5 or more years of endocrine therapy. Data have so far been received on 7,488 women in trials of extended aromatase inhibitor therapy after tamoxifen alone, 10,796 women after prior tamoxifen then treatment with an aromatase inhibitor, and 959 women after aromatase inhibitor therapy alone.

A preliminary analysis revealed a 35% reduction in recurrence with extended aromatase inhibitor therapy after tamoxifen alone compared with no continued aromatase inhibitors beyond 5 years (7.1% vs. 10.7%, respectively). The researchers noted that a more moderate reduction was observed after prior treatment with aromatase inhibitors. Final results of the meta-analysis will include 2 more trials, contributing data from 5,666 additional women.

Disclosure: The study authors’ disclosure information may be found at

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