CHICAGO – Vitamin D3 can relieve the aches and pains associated with aromatase inhibitor therapy for breast cancer, according to the results of a randomized, double-blind, placebo-controlled trial.
Six months of vitamin D at 30,000 IU per week proved safe and was associated with "less worsening" of musculoskeletal events and fewer overall adverse quality of life events in women starting adjuvant letrozole (Femara) for hormone receptor–positive breast cancer, Dr. Qamar J. Khan reported at the annual meeting of the American Society of Clinical Oncology.
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Several months of vitamin D can ease the discomfort stemming from aromatase inhibitor therapy for breast cancer.
Aromatase inhibitors are often discontinued prematurely because of new or worsening musculoskeletal pain reported in as many as half of women and fatigue in 15%-30%, said Dr. Khan of the University of Kansas Medical Center in Kansas City.
Vitamin D deficiency is thought to contribute to musculoskeletal symptoms, he said, explaining the rationale for the study. It is prevalent in breast cancer patients who have these aches and pains, and in women receiving adjuvant chemotherapy, even with supplementation. A similar syndrome is seen in people with severe vitamin D deficiency, he noted.
A prior pilot study conducted by the investigators suggested that vitamin D at 50,000 IU/wk for 12 weeks may be effective in reducing these symptoms (Breast Cancer Res. 2010;119:111-8).
The current double-blind VITAL (Vitamin D for Arthralgias From Letrozole) trial evenly randomized 160 postmenopausal women with stage I-III hormone receptor–positive invasive breast cancer and a serum vitamin D level of 40 ng/mL or less. All patients received letrozole 2.5 mg daily and the standard daily recommended daily allowance (RDA) of vitamin D 600 IU and calcium 1,200 mg. One cohort also received 30,000 IU of oral vitamin D3 weekly for 24 weeks; the other was given a placebo.
The two arms were well matched with regard to age, race, body mass index, vitamin D level at baseline, adjuvant chemotherapy, and radiation therapy.
The per-protocol primary end point was the incidence of a musculoskeletal event, defined as worsening of pain using a simple pain intensity scale, worsening disability from musculoskeletal pain using the Health Assessment Questionnaire II, or discontinuation of letrozole because of pain at 6 months. The primary end point also was measured, substituting the quantitative Brief Pain Inventory for the simple pain intensity scale, Dr. Khan said.
Thirteen patients did not complete the study for reasons unrelated to study agents and/or musculoskeletal events, leaving 147 evaluable for efficacy.
At 6 months, 37% of women receiving 30,000 IU vitamin D weekly experienced a per-protocol musculoskeletal event, compared with 51% on placebo (P = .069), based on the simple scale. When the more robust Brief Pain Inventory was used, 61% of controls and 38% of those on vitamin D reported a musculoskeletal event, a difference that reached statistical significance (P = .008), he said.
A significantly higher proportion of women on placebo also had an adverse quality of life event, defined as a musculoskeletal event plus worsening of fatigue (72% vs. 42%; P less than .001).
The median vitamin D level at baseline was 25.1 ng/mL in the control arm and 22.5 ng/mL in the vitamin D group. It hovered at 32 ng/mL at 12 weeks and 31 ng/mL at 24 weeks in the control group, but rose to 53 ng/mL at 12 weeks and 57 ng/mL at 24 weeks in the vitamin D arm (P = .001 at both 12 and 24 weeks).
Baseline levels had little influence on the final level achieved. The sharp rise followed by relatively little gain in the active treatment arm suggests a plateau in the effect of continued vitamin D supplementation, Dr. Khan observed.
One patient in the control arm developed mild hypercalcemia, and three patients in the control arm discontinued early because of a musculoskeletal adverse event. There were no severe adverse events.
Discussant Karen Mustian, Ph.D., of the University of Rochester (N.Y.) Medical Center, said that the trial used well-validated measures and showed no discernable toxicity with 30,000 IU weekly, which is beyond the current RDA. "Therefore it may be promising for helping with these musculoskeletal symptoms and possibly fatigue," she said.
Dr. Mustian asked whether the time needed to achieve a benefit poses a potential problem in terms of patient adherence and whether data are available on the sustainability of the improvements in musculoskeletal symptoms and fatigue.
Dr. Khan said that aromatase inhibitor–induced adverse events tend to peak at about 6 months and that only one study has looked at using higher doses of vitamin D beyond 6 months. The observation that the effect of vitamin D supplementation plateaus at 3-6 months, however, is consistent with other studies.