High-dose vitamin D relieves pain and fatigue associated with aromatase inhibitor therapy

High-dose vitamin D supplementation can provide relief of symptoms related to vitamin D deficiency from aromatase inhibitor therapy in postmenopausal women with breast cancer, said Q.J. Khan, MD, Cancer Center of Kansas, Wichita.

Approximately one-fourth of women with invasive breast cancer who receive adjuvant aromatase inhibitors experience joint pain or stiffness. Approximately one-fourth also report fatigue during treatment with an aromatase inhibitor. Vitamin D deficiency is a potential cause of the musculoskeletal pain in women who are taking aromatase inhibitors.

In a 16-week prospective study, 60 women with invasive breast cancer who were candidates for aromatase inhibitor therapy had serum vitamin D levels measured at baseline, 10 weeks, and 16 weeks. For all women, treatment with letrozole 2.5 mg/d and calcium 1,200 mg/d plus vitamin D 600 IU/d was initiated. Women who had serum vitamin D levels of 40 ng/mL or lower at Week 4 had the vitamin D dosage increased to 50,000 IU/d for the next 12 weeks.

Fatigue, pain severity, joint pain disability, and menopausal symptoms were assessed via questionnaire at baseline, Week 4, and Week 16.

Sixty-four percent of the women had vitamin D deficiency (<32 ng/mL) at baseline; 49 of the 50 women who received high-dose vitamin D had serum vitamin D levels >32 ng/mL by Week 10. With standard-dose (600 IU/d) vitamin D, serum vitamin D levels dropped in 7 of 9 women.

During treatment with standard-dose vitamin D, joint pain improved in 8% of women and worsened in 34%. When the vitamin D-deficient women at Week 4 were switched to high-dose vitamin D, joint pain improved in 21% of the patients and worsened in 32% from Weeks 4 through 16.

Similarly, fatigue scores were more likely to improve during high-dose vitamin D therapy and were more likely to worsen during standard-dose vitamin D therapy.

Health Assessment Questionnaire II scores, designed to study the effects of an intervention on activities of daily living, were stable from baseline to Week 4 (during standard-dose vitamin D therapy) but declined (improved) from Week 4 to 16 (during high-dose vitamin D therapy).