- High-dose vitamin D3 fails to prevent aromatase inhibitor-induced arthralgia (AIA) in postmenopausal women with hormone receptor (HR)-positive breast cancer (BCa).
- Study was terminated early, based on results of planned futility analysis.
Why this matters
- AIA affects 50% of recipients of AI therapy.
- Results suggest that vitamin D3 plays no role in AIA onset.
- Randomized controlled trial of standard-dose vitamin D3 (800 international units [IU]/day planned for 52 weeks) vs high-dose vitamin D3 (50,000 IU/week for 12 weeks, followed by 2000 IU/day planned for 40 weeks) in patients starting AI therapy.
- Futility analysis was planned when half of patients were enrolled.
- 93 patients (47 standard dose; 46 high dose) were evaluated for efficacy at 12 weeks.
- High-dose group had higher mean serum level of vitamin D3 at 12 weeks (50 vs 29.3 ng/mL in the standard-dose group; P<.0001>
- No difference in the development of AIA between groups (54% of high-dose vs 57% of standard-dose groups; 1-tailed P value=.3818, leading to early termination of study for futility).
- 1 patient in the high-dose group developed renal stones.
- Many patients were counted as failures because they did not complete questionnaires.