The bone-targeting radioisotope radium-223 has delivered promising results in a randomised trial to test its efficacy in treatment of hormone-refractory prostate cancer (HRPC). The findings are reported early Online - timed to coincide with presentation of the paper at the American Society of Clinical Oncology meeting in Chicago and in an upcoming edition of The Lancet Oncology.

Patients who have HRPC often have involvement of bone marrow, leading to symptoms such bone pain, spinal-cord compression and pathological fracture. Existing bone-targeted treatments, such as use of the beta-emitting radioisotope strontium-89 have been shown to reduce bone pain.

Dr Christopher Parker, Institute of Cancer Research and Royal Marsden Hospital, Sutton, UK and colleagues did a study of 64 patients with HRPC. Radium 223 was chosen because it emits alpha radiation which has higher energy and travels less distance than the beta radiation. Thus Parker and colleagues believe that alpha radiation will have a more pronounced localised effect on tumours.

The patients were randomly assigned to two groups. In the first, 33 received external-beam radiotherapy and up to four injections of radium-223. The other group received the same radiotherapy and placebo.

Levels of bone alkaline phosphatase (bone-ALP) considered a marker for progression of HRPC decreased by 66% in the group receiving radium-223. The length of time for patients HRPC to progress - as assessed by each prostate-specific-antigen concentration was much longer for those receiving radium 223 (26 weeks) compared to placebo (eight weeks). The median survival time for radium-223 patients was 41% longer than those receiving placebo (65.3 weeks vs 46.4 weeks respectively); and no Radium-223 patients stopped treatment due to treatment toxicity

However, radium-223 treatment had no significant effect on the timing of skeletal related events (SREs) another key indicator of HRPC
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Contact: Dr. Christopher Parker
chris.parker@icr.ac.uk
44-020-866-13425
Lancet
2-Jun-2007