This study was conducted to see whether a high intake of vitamin D2 by women suffering from breast cancer, who are using drugs such as anastrozole, could help prevent certain muscle-related side effects like muscle pain and loss of bone mass. On supplementation with vitamin D, the severity of pain from musculoskeletal disorders and the need for medications were significantly reduced. Furthermore, the bone density remained stable in those receiving vitamin D2 supplementations, indicating reduced bone loss.
Studies have shown that women with early-stage breast cancer who receive drugs anastrozole, letrozole, or exemestane, which are aromatase inhibitors, often complain of acute muscle aches and pain. These symptoms are collectively termed as aromatase inhibitor-induced musculoskeletal symptoms or AIIMS. As many as 19 to 35 percent of women taking aromatase inhibitors complain of AIIMS. Pain and discomfort in the hands, lower back, hips, shoulders, knees and feet, often associated with stiffness, are common complaints of women taking these drugs. This is also an important reason why many women refuse to continue these drugs, in spite of their proven benefits in breast cancer. Some researchers have found that lower levels of vitamin D (20 to 29 ng/ml) in the blood could be responsible for a predisposition to AIIMS. Vitamin D levels above 30 ng/ml in blood are considered normal. Some studies suggested that vitamin D might play a role in prevention or treatment of AIIMS. This study attempted to test such theories.
* For this study, 60 women who were diagnosed with early-stage breast cancer were recruited. At the beginning of the study, the levels of vitamin D in their blood were measured and their bone density was scanned. The women were divided into two groups – those in Stratum A had vitamin D levels between 20 and 29 ng/ml and those in Stratum B had vitamin D levels between 10 and 19 ng/ml.
* Half of the women in Stratum A were given vitamin D capsules, containing 50,000 international units (IU), once a week for eight consecutive weeks, followed by once a month for four months. The other half were given placebos. Those in Stratum B were also divided into two groups. One group received vitamin D capsules containing 50,000 IU for 16 weeks and then once a month for two months. The other group received placebos.
* For all the participants, AIIMS was assessed using the “Brief Pain Inventory (BPI) Short form” and other questionnaires at the beginning of the study, and thereafter at the second, fourth, and sixth months of the study. The bone density at the upper part of the thighbone was also scanned before and after the study.
* At the beginning of the study, there was no significant difference between those who received vitamin D and those who did not.
* At the end of 2 months, symptoms of musculoskeletal pain were improved among those who were given high dose of vitamin D in both strata A and B, compared to those who were given placebos. However, when the vitamin D supplementation was switched from weekly to monthly, no effect was observed on the severity of pain.
* For those who were given placebos, there was deterioration in the bone density. However, bone density remained stable in those who received vitamin D supplementation.
The authors of this study agree that they did not know the exact pathology that links aromatase inhibitors with AIIMS. While associations with low estrogen levels, or malfunctioning of the parathyroid glands (glands that regulate bone and calcium metabolism in the body) are speculated, further studies on this aspect are needed.
This study evaluated the effects of vitamin D supplementation in women who develop muscle and bone-related symptoms while using aromatase inhibitors for the treatment of breast cancer. It was seen that vitamin D not only relieves the symptoms of AIIMS-related muscle aches and pains, but also prevents bone loss that is a common side effect of consuming aromatase inhibitor drugs. The authors suggest that further insights into the actual functioning of vitamin D in relieving these symptoms are needed. Aromatase inhibitors are important in the therapy of breast cancer, and AIIMS often lead women into discontinuing the drugs prematurely. Optimum dosage and schedule of vitamin D supplementation in these women need to be clarified for relieving the side effects of these drugs.
For More Information:
Vitamin D and Aromatase Inhibitor-induced Musculoskeletal Symptoms (AIMSS): A Phase II, Double-Blind, Placebo-Controlled, Randomized Trial
Publication Journal: Breast Cancer Research and Treatment, June 2011
By Antonella L. Rastelli; Marie E. Taylor; Washington University School of Medicine, St. Louis, Missouri