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, associate professor of oncology, Cancer Center of Kansas, Wichita.

"All women starting an aromatase inhibitor should be screened for vitamin D deficiency, and attempts should be made to optimize vitamin D levels," said Dr. Khan.

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).