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According to a study published in the journal Cancer, men with prostate cancer who are receiving androgen deprivation therapy are not being adequately evaluated or treated for bone loss.

Prostate CancerConnect 490

Prostate cancer is the second leading cause of cancer deaths among men in the United States. The prostate is a walnut-sized gland that is located between the bladder and the rectum. It is responsible for the formation of components of semen. Prostate cancer cells are thought to be stimulated to replicate excessively by male hormones, particularly testosterone. Therefore, a standard therapeutic approach, particularly in men with advanced stages of prostate cancer, is referred to as hormone therapy or androgen deprivation therapy, in which the levels of testosterone available to cancer cells are drastically reduced. Prior clinical studies have indicated a trend towards loss of bone density (osteoporosis) and increases in the risk of bone fractures in men treated with androgen deprivation therapy. However, there has been no standardized way in which to monitor bone effects in men undergoing androgen deprivation therapy.

Researchers from Loyola University conducted a study to determine the trends of physicians in evaluating and treating their patients for bone loss among their prostate cancer patients undergoing androgen deprivation therapy. The study included 148 men, all of whom had been receiving long-term androgen deprivation therapy. The men were at a high risk of osteoporosis for factors other than treatment, including the following: “smoking, alcoholism, advanced age, low body mass index, history of bone fractures, steroid use” and multiple other medical problems. Overall, only 14.7% of patients underwent screening or treatment measures for osteoporosis and general health practitioners tended to provide more interventions regarding bone effects than cancer-related specialists. Of these men, only 8.7% were offered a Dexa Scan (type of scan to determine bone density) as well as calcium or vitamin D supplementation, and only 5.4% were treated with oral or intravenous (IV) bisphosphonates, a type of drug that reduces bone loss. Approximately 75% of men who underwent a Dexa Scan suffered from bone loss.

The researchers concluded that men with prostate cancer who are undergoing androgen deprivation therapy are infrequently receiving evaluation or treatment of the bone effects of their therapy.  Patients with prostate cancer who are undergoing androgen deprivation therapy may wish to speak with their physicians about evaluation, treatment and/or prevention of bone loss.

Prevention of Bone Loss

Zometa® (zoledronic acid) reduces bone loss and promotes bone recovery among prostate cancer patients treated with androgen deprivation therapy.

Treatment with androgen deprivation therapy can have such adverse effects on bone as reductions in bone mineral density, increased risk of fractures, and osteoporosis.

Studies indicate that treatment with the bisphosphonate drug Zometa slows loss of bone mineral density when given at the start of androgen deprivation therapy, but it’s uncertain whether it remains effective when started after androgen deprivation therapy has already begun.

Researchers from 19 U.S. medical centers conducted a randomized clinical trial to evaluate the effect of Zometa on bone loss. They studied 101 men with prostate cancer who had already received up to a year of androgen deprivation therapy. Patients were randomly assigned to receive either Zometa (4 mg IV every 3 months for up to one year) or placebo. Men continued treatment with androgen deprivation therapy during the study and also took calcium and vitamin D supplements. Bone mineral density was measured at baseline (6 months) and 12 months.

Treatment with Zometa was found to have a positive effect on bone mineral density.

Men who had been on androgen deprivation therapy for less than six months before starting Zometa had the following results:

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  • Bone mineral density at the hip increased 0.9% for those on Zometa and decreased 3.1% for those on placebo.
  • Bone mineral density at the lumbar spine increased 4.9% for those on Zometa and decreased 2.1% for those on placebo.

Men who had been on androgen deprivation therapy for 6-12 months before starting Zometa had these results:

  • Bone mineral density at the hip increased 2.4% for those on Zometa and decreased 0.6% for those on placebo.
  • Bone mineral density at the lumbar spine increased 4.0% for those on Zometa and decreased 2.1% for those on placebo.

According to an article published in Urology, further evidence indicates that treatment with Zometa (zoledronic acid) for one year prevents bone loss in patients with advanced prostate cancer who are undergoing hormone therapy.

Researchers from several institutions in the U.S. recently conducted a clinical trial to further evaluate whether treatment with Zometa can reduce bone loss in men with prostate cancer that has already spread to the bone. This study included 221 patients who were receiving hormone therapy. On trial, all men received treatment with Zometa for one year.

  • Bone mineral density increased by 7.7% in the lumbar spine.
  • Bone mineral density increased by 3.6% in the hip.
  • Joint pain, nausea, fatigue and back pain were the most frequent side effects reported.
  • The median time to a skeletal event (bone fracture, osteoporosis, etc.) had not been reached.
  • Nearly 12% of patients experienced a skeletal-related event.

The most common side effects associated with Zometa were nausea, hot flashes, fatigue, and bone pain.

Treatment with Zometa not only reduces bone loss associated with androgen deprivation therapy in men with prostate cancer, but also recovers bone. The researchers also stated that Zometa was safe and well tolerated.

Prostate Cancer Newsletter 490

References: 

  1. Ryan C, Beer T, Huo D, et al. A randomized, placebo-Controlled, Trial of Zoledronic Acid for Bone Loss Initiated During the First Year of Androgen Deprivation Therapy in Prostate Cancer Patients. Proceedings from the 2005 annual Chemotherapy Foundation Symposium. November 2005. New York, NY. Abstract #58.
  2. Polascik T, Given R, Metzger C, et al. Open-label trial evaluating the safety and efficacy of zoledronic acid in preventing bone loss in patients with hormone-sensitive prostate cancer and bone metastases. Urology. 2005; 66: 1054-1059.
  3. Tanvetyanon T. Physician practices of bone density testing and drug prescribing to prevent or treat osteoporosis during androgen deprivation therapy. Cancer. 2005;103:237-241.