- Aromatase inhibitor (AI) therapy for breast cancer (BCa) is not associated with higher risk for fracture, according to a Canadian registry-based cohort study.
Why this matters
- Although findings may be offset by higher baseline BMI, bone mineral density (BMD), and lower prevalence of prior fracture in AI-treated women, the study challenges conventional wisdom that all women starting AI therapy are at high risk for fracture.
- Population-based, registry-based cohort (n=36,996) of women entered into a BMD registry for Manitoba, Canada.
- Women aged ≥40 years were divided into 3 mutually exclusive groups:
- BCa with ≥12 months of AI therapy (n=1775).
- BCa with no AI therapy (n=1016).
- General population (n=34,205).
- Participants were linked to hospital discharge and physician billing claims.
- Funding: None disclosed.
- At baseline, the AI group had higher BMI, higher BMD, lower osteoporosis prevalence, and fewer fractures than the other 2 groups (all P<.001>
- Median total exposure to AI, 4.2 years.
- In adjusted analysis, the AI group had similar risks as the general population for:
- Major osteoporotic fracture (hip, clinical spine, forearm, and humerus; HR, 1.15; 95% CI, 0.93-1.42).
- Hip fracture (HR, 0.90; 95% CI, 0.56-1.43).
- Any fracture (HR, 1.06; 95% CI, 0.88-1.28).
- Observational design.