Yael Waknine

June 25, 2012

June 25, 2012 (Chicago, Illinois) — Supplementation with vitamin D3 may enable breast cancer survivors to adhere to adjuvant treatment with aromatase inhibitors, according to research presented here at the 2012 Annual Meeting of the American Society of Clinical Oncology.

Researchers found that women taking 30,000 IU of oral vitamin D3 weekly on starting letrozole therapy achieved significant benefits in terms of fatigue, joint pain, and disability from joint pain.

"Aromatase inhibitors are one of the most important endocrine treatments for breast cancer, but the problem is that about half of the women have severe musculoskeletal pain from these agents, and 18% to 30% report fatigue, [resulting in] a discontinuation rate of about 10% each year," Qamar J. Khan, MD, from the University of Kansas Medical Center, Kansas City, told Medscape Medical News in an interview. He added that pain relievers are the only available treatment option.

Debra Barton, PhD, RN, from the Mayo Clinic College of Medicine in Rochester, Minnesota, who was not involved in the study, says she finds the results "intriguing."

"There's been a lot of data to support the fact that in various populations, vitamin D levels can be less than what we want them to be and are associated with some of the pain syndromes that are similar to the syndrome of discomfort and pain that's experienced with taking aromatase inhibitors," Dr. Barton told Medscape Medical News.

Fewer Report Musculoskeletal Effects

For the study, 147 evaluable women with stage I to III breast cancer were enrolled to receive letrozole therapy and standard supplementation with vitamin D3 (600 IU) and calcium (1200 mg).

Participants were then randomly assigned to receive either 30,000 IU of oral vitamin D3 or placebo weekly for 6 months.

Results showed that weekly vitamin D supplementation yielded a significant increase in serologic 25(OH)D levels during the first 3 months (22 ng/mL to 53 ng/mL) and then stabilized during the remaining 3 months (week 24, 57 ng/mL).

According to Dr. Khan, 25(OH)D levels below 20 ng/mL are considered deficient for bone health, which is particularly crucial for women taking aromatase inhibitors, as they can cause bone loss as an adverse effect.

Using the Simple Descriptive Pain Intensity scale for analysis, only 37% of women receiving vitamin D3 supplementation reported a musculoskeletal event (joint pain, disability from joint pain, or resulting discontinuation of letrozole) at 6 months compared with 51% of those in the placebo group (P = .069).

In addition, significantly fewer patients receiving vitamin D3 supplementation reported adverse quality of life events, including worsening of pain, disability, or fatigue (42% vs 72%; P < .001). Vitamin D supplementation was not associated with any adverse events, including stones and hypercalcemia.

Physicians Debate Whether to Implement Screening and Treatment Measures

According to Dr. Khan, a baseline 25(OH)D level should be obtained before treatment with aromatase inhibitors and addressed accordingly.

"We believe that once a person achieves a certain vitamin D level and continues supplementation, the level stabilizes. Based on that data, vitamin D [therapy] can be continued beyond 6 months. The only recommendation would be to check vitamin D levels once a year," Dr. Khan advised.

"I think that the study is intriguing," Dr. Barton commented. "The issue is really important and worthy of further study and addressing because it not only makes a difference in health-related quality of life but [also affects] the ability of patients to get the treatment that they need for their disease."

However, the question of whether vitamin D screening and supplementation should be implemented remains "quite an issue of debate," she added.

"How long do we continue supplementation? Once you get people to a certain level, how do you maintain that, and do you have to vary the dose depending on the season or climate? How often do you check? These are all very important context issues to consider, and I don't know that we have the data to guide us in that. If you are going to supplement, that all needs more study," Dr. Barton concluded.

According to Dr. Khan, a 2-year study is being planned.

Dr. Barton and Dr. Khan have disclosed no relevant financial relationships.

2012 Annual Meeting of the American Society of Clinical Oncology: Abstract 9000. Presented June 4, 2012.

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