DNC News:  Vitamin D Reduces Aromatase Inhibitor Induced Arthralgia
Jacob Schor, ND, FABNO
September 1, 2009

We were told this would help but weren’t 100% sure it did.  Now there is fairly good evidence that taking adequate doses of vitamin D will reduce the most limiting side effect from the new class of drugs, aromatase inhibitors, used to treat postmenopausal breast cancer.
Researchers at the University of Kansas Medical Center enrolled sixty women into the study as they started taking the drug letrozole, sold as Femara, to see whether vitamin D suppementation could reduce the side effects produced by the drug.  The study participants who at the start of the study had vitamin D levels of 40 ng/ml or less, were given 50,000 IU of vitamin D each week.        At the start of the study 63% of the women were judged vitamin D deficient, that is had a 25(OH)D level less than 20 ng/ml.  After 12 weeks all the women had vitamin D levels above 40 ng/ml.     After 16 weeks of taking letrozole, women with high normal vitamin D levels, above 66 ng/ml, reported significantly fewer complaints, almost a third the number (52 vs. 19%; P = 0.026), compared to those with lower levels of vitamin D. 
The take home lesson is that our therapeutic goal for vitamin D levels in women using aromatase inhibitors is higher than commonly thought.  Many laboratories and health care organizations still tell patients that having vitamin D levels greater than 20 (Kaiser) or 30 (Quest) ng/ml is adequate.  At least in menopausal women undergoing treatment for breast cancer, a higher level of vitamin D is required to prevent the joint and muscle pain often associated with this therapy.
Our prior and more complete newsletter on Aromatase Inhibitors and Arthralgia:
Note: a special thank you to Dr. Katherine Neubauer, a naturopathic physician who works with Cancer Treatment Centers of America, for pointing out this recent study to me
] Breast Cancer Res Treat. 2009 Aug 5.
Effect of vitamin D supplementation on serum 25-hydroxy vitamin D levels, joint pain, and fatigue in women starting adjuvant letrozole treatment for breast cancer.
Khan QJ, Reddy PS, Kimler BF, Sharma P, Baxa SE, O'Dea AP, Klemp JR, Fabian CJ.
Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, USA, qkhan@kumc.edu.
Vitamin D deficiency and insufficiency may contribute to musculoskeletal symptoms and bone loss observed in women taking aromatase inhibitors (AIs). This study was conducted to determine the prevalence of suboptimal vitamin D levels in women initiating adjuvant letrozole for breast cancer and to determine whether supplementation with 50,000 IU of vitamin D3 weekly could reduce musculoskeletal symptoms and fatigue in women who have suboptimal vitamin D levels. Sixty women about to begin an adjuvant AI were enrolled. Baseline 25OHD levels were obtained, and women completed symptom questionnaires. They were then started on letrozole, along with standard dose calcium and vitamin D. Four weeks later, women with baseline 25OHD levels </=40 ng/ml started additional vitamin D3 supplementation at 50,000 IU per week for 12 weeks. 25OHD levels were re-assessed at 4, 10, and 16 weeks; the questionnaires were repeated at weeks 4 and 16. At baseline, 63% of women exhibited vitamin D deficiency (<
ng/ml) or insufficiency (20-31 ng/ml). 25OHD levels >40 ng/ml were achieved in all 42 subjects who received 12 weeks of supplementation with 50,000 IU vitamin D3 weekly, with no adverse effects. After 16 weeks of letrozole, more women with 25OHD levels >66 ng/ml (median level) reported no disability from joint pain than did women with levels <66 ng/ml (52 vs. 19%; P = 0.026). Vitamin D deficiency and insufficiency are prevalent in post-menopausal women initiating adjuvant AI. Vitamin D3 supplementation with 50,000 IU per week is safe, significantly increases 25OHD levels, and may reduce disability from AI-induced arthralgias.
PMID: 19655244 [PubMed - as supplied by publisher]