Researchers involved in a multicenter international trial have reported that normalization of N-telopeptide of type I collagen (NTX) levels is associated with skeletal-related events and survival among patients with bone metastases from solid tumors treated with Zometa® (zoledronic acid) or Aredia® (pamidronate). These results were published in the July 1, 2008 issue of Cancer.

Bone metastasis is a common and difficult issue with cancer patients, particularly patients with cancer that originates in the breast, prostate, lung, or those with multiple myeloma. Treatment for bone metastases may include radiation therapy to the site of bone metastases, hormone therapy, chemotherapy, or bisphosphonate therapy with agents such as Zometa or Aredia.

Treatment for bone metastatses has demonstrated a reduction in skeletal-related events (SREs) as well as a delay of onset of SREs among patients with bone metastases. SREs can include bone fractures, debilitating pain, and/or compression of the spine. Researchers are now evaluating ways in which to measure responses to therapy for bone metastases; specially, they are evaluating certain bone markers and their association with outcomes for patients.

High levels NTX are linked to increased risk of death and SRE among patients with bone metastases. However, the association between a reduction in NTX levels and associated outcomes among these patients is not clearly understood.

Researchers from the United States, Canada, and Europe recently evaluated data from three large clinical trials in an attempt to clarify the association between changing NTX levels and outcomes among patients being treated for bone metastases. The three trials in this analysis included patients with prostate cancer, lung cancer, breast cancer, and other solid tumors who were treated with either Zometa, Aredia, or placebo for up to two years. Levels of NTX were evaluated along with outcomes for these patients.

• For patients who initially had elevated NTX levels, those who achieved normalization of NTX levels following three months of therapy had significantly improved overall survival compared with those who experienced consistently elevated NTX levels.
• The larger the percentage reduction of NTX levels, the greater the improvement of survival for these patients.
• Among patients who initially had elevated NTX levels, those treated with Zometa had greater rates of normalization of NTX levels compared with those treated with Aredia.

These researchers concluded: “Zoledronic acid normalizes or maintains normal NTX levels in most patients with bone metastases. Normalized NTX within 3 months of treatment, versus persistently elevated NTX, was associated with reduced risks of skeletal complications and death.” Patients with bone metastases may wish to speak with their physician regarding their individual risks and benefits of all treatment options.

Comments: These data appear to confirm the superiority of Zometa for treatment of bone metastases over other bisphosphonates.

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The FDA Approves Zometa® for the Treatment of Bone Metastases Associated with a Broad Range of Tumor Types (2/26/2002)

Reference: Lipton A, Cook R, Saad F, et al. Normalization of bone markers is associated with improved survival in patients with bone metastases from solid tumors and elevated bone resportion receiving zoledronic acid. Cancer. 2008:113; 193 – 201.