Rx for Prostate Cancer Not for All Men

Zoledronic acid did not stop prostate cancer spread to bones in some men

(RxWiki News) Preventing the spread of prostate cancer to bones can mean fewer fractures and slower progression of cancer. One medication used for this purpose appears safe, but may not be effective in some patients.

Early prostate cancer that shows improvement from hormone-reducing treatment is called castration-sensitive prostate cancer. When prostate cancer stops responding to hormone therapy, it is then called castration-resistant prostate cancer.

Zoledronic acid (brand name Zometa) is approved to treat prostate cancer and cancer that has spread to the bones (bone metastases) in men with castration-resistant prostate cancer.

Zoledronic is also being used to treat men in the early stages of prostate cancer when their disease is still castration-sensitive, but the safety and effectiveness of the medication in these men has not been confirmed.

Recently published research showed that, in cases of early castration-sensitive prostate cancer, zoledronic did not reduce bone problems or increase survival.

"Discuss prostate cancer treatment options with your oncologist."

Matthew R. Smith, MD, PhD, from Massachusetts General Hospital Cancer Center in Boston, MA led this research team.

Androgens are a group of hormones that include testosterone. Reducing androgens by surgery or medication is often an effective treatment for early prostate cancer. Early prostate cancer that responds to therapy to reduce hormones is called castration-sensitive prostate cancer.

Eventually, prostate cancer progresses despite hormone therapy. At this point, the cancer is referred to as castration-resistant prostate cancer.

The study recruited 645 patients with early castration-sensitive prostate cancer that had spread to at least one bone site. The average age of these patients was 66 years old.

The patients were divided into two groups. One group received zoledronic acid intravenously every four weeks and one group received intravenous salt solution, containing no medication, as a placebo.

The researchers looked for signs the cancer was spreading to the bones. They also kept track of bone problems, such as fractures, and overall survival of the patients.

The average time to bone problems was similar in both groups, at 32 months in the treated group and 29 months in the placebo group.

The amount of time before the cancer spread more was also similar in the two groups. This was about 10.5 months in the zoledronic acid group and about nine months in the placebo group.

Overall survival was also similar in men in both groups. The treated group lived about 38 months from when they started the study and the placebo group lived about 36 months.

About the same number of patients in each group reported serious adverse events. Most of the serious problems reported were pain, low blood phosphate and calcium and fatigue.

One limitation of this study was that treatment had to stop before all patients reached a point where they either had bone metastases or had other bone problems. This was due to lack of availability of the study medication.

The authors of this study concluded that their results did not support the routine use of zoledronic acid to prevent bone problems in men with metastatic prostate cancer before it became castration-resistant.

This research was published in the March issue of The Journal of Clinical Oncology.

Funding for the study was provided by the National Cancer Institute.

Two researchers in the study disclosed receiving compensation for a consultant or advisory role with Novartis, manufacturers of Zometa.

Review Date: 
March 6, 2014