Breast cancer patients taking Arimidex may get pain relief from vitamin D

Breast cancer patients taking the drug Arimidex to prevent recurrence of their disease sometimes suffer from bone, muscle or joint pains. Giving these patients vitamin D supplements can make the pain go away in some cases, according to Washington University physicians who treat cancer patients at the Siteman Cancer Center and Barnes-Jewish Hospital.

Now these physicians are seeking to confirm their clinical observations in a controlled study, and they are calling for participation by women taking Arimidex (chemical name anastrozole) who have musculoskeletal pain.

Arimidex is an aromatase inhibitor, which completely blocks production of estrogen, the hormone implicated in the growth of many breast tumors.

“Arimidex has been shown to be even better than tamoxifen (brand name Nolvadex) in protecting breast cancer patients from recurrence of cancer, so now most patients with estrogen-receptor-positive breast cancer receive Arimidex,” says Antonella Rastelli, M.D., instructor in medicine. “Unfortunately, about one-third of patients on Arimidex will experience significant joint tenderness, stiffness or muscle or skeletal pain.”

Rastelli’s colleague, Marie Taylor, M.D., assistant professor in radiation oncology, has found that many patients with these symptoms also have below-optimal levels of vitamin D in their blood, and when given vitamin D supplements, these patients often have a complete resolution of their pain.

Rastelli and Taylor are initiating a double-blind, placebo-controlled study of Arimidex takers with muscle and bone pain to try to confirm the connection between vitamin D supplementation and pain relief. Half of the study participants will receive a high-dose vitamin D supplement once a week while the other half receives an inactive placebo. Questionnaires that the patients fill out before and during the six-month study will allow the researchers to assess the effect of high-dose vitamin D on patients’ musculoskeletal pain.

“We aren’t certain why Arimidex would be associated with low levels of vitamin D, but scientists theorize that the drug depletes the body’s stores of vitamin D by interfering with enzymes in the liver that process the vitamin,” Rastelli says. “It’s also interesting to note that vitamin D is scarce in most people’s diets, coming mainly from whole milk, liver and fatty fish. The majority of vitamin D is produced in the skin in reaction to sunshine, but increasing avoidance of the sun and the use of sunscreens reduce that source, so it is relatively easy to become vitamin D deficient.”

Vitamin D has wide-ranging effects in the body, including regulating cell growth, immune function, blood pressure and insulin secretion. It is also essential for calcium absorption and so is involved in maintaining bone health.

All patients participating in the study will receive daily calcium and low-dose vitamin D supplements equivalent to the recommended daily allowances in addition to their weekly vitamin D supplement or placebo. All participants also will receive a bone density scan.

Women are eligible to participate in the study if they have completed at least eight weeks of Arimidex therapy and have generalized musculoskeletal pain with or without localized areas of discomfort that have developed or worsened since starting Arimidex therapy.

To participate or to get more information, call 314-362-2529 or 314-747-3056 and ask about the vitamin D study.

Funding from AstraZeneca will support this research.

Washington University School of Medicine’s full-time and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked third in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Siteman Cancer Center is the only NCI-designated Comprehensive Cancer Center within a 200-mile radius of St. Louis. Siteman Cancer Center is composed of the combined cancer research and treatment programs of Barnes-Jewish Hospital and Washington University School of Medicine.