- The American Society of Clinical Oncology (ASCO) updates its guidelines on endocrine therapy for breast cancer risk reduction within a week of a similar update by the US Preventive Services Task Force (USPSTF).
- ASCO adds anastrozole (1 mg/day) to the list of medication options for postmenopausal women.
Why this matters
- ASCO's recommendations were last issued in 2013, when they first added the aromatase inhibitor (AI) exemestane; USPSTF did not add any AIs until 2019.
- ASCO and USPSTF both recommend AIs, raloxifene, or tamoxifen expressly for postmenopausal women; tamoxifen is the only option for premenopausal women.
- ASCO recommendations offer more detail regarding the adverse effect of AIs on bone health.
- Before prescribing AIs, ASCO recommends that clinicians evaluate patients for fracture risk and measure their bone mineral density (BMD).
- Clinicians should be cautious about prescribing anastrozole in postmenopausal women with moderate BMD loss.
- If clinicians do prescribe anastrozole for this subset of women, they should consider co-prescribing bone-protective agents such as bisphosphonates and receptor activator of nuclear factor κ-B ligand (RANKL) inhibitors.
- Anastrozole should not be used in women with a history of osteoporosis and/or severe bone loss.
- Tamoxifen and raloxifene are alternative breast cancer-reducing medications that do not lower BMD.