Vitamin D3 for Aromatase Inhibitor Induced Arthralgias

The primary hypothesis is that high dose vitamin D3 plus standard dose vitamin D3 prevents the worsening of musculoskeletal symptoms when compared to a standard dose vitamin D3 treatment. This protocol will examine the relationship between vitamin D levels (25-hydroxyvitamin D) and various quality of life measures in women being treated with letrozole as standard care for early stage breast cancer. All subjects received letrozole and a standard dose of vitamin D3 (600 IU daily). Randomization was between high dose vitamin D3 (30,000 IU once per week) vs. a blinded, matched placebo,