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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
The drug zoledronic acid delayed the onset of bone complications by two months in men with prostate cancer that had spread to the bone. Though it did not increase overall survival, it improved quality of life by reducing important complications such as fractures and spinal cord compression.
The radioactive drug strontium-89 was also tested and delayed the combined outcome of bone-related complications, pain or death by about one month. It also had no effect on overall survival or the number of bone complications.
Both treatments were compared with chemotherapy alone. Current NICE guidance recommends strontium-89 to treat prostate cancer that has spread to the bone, but not zoledronic acid unless other treatment has failed due to costs. The branded version of zoledronic acid did not give value for money but cheaper generic versions, now available, could be a better use of NHS resources.
Why was this study needed?
Prostate cancer is the second most common cause of cancer deaths in men in the UK. Just over 10,000 men died from prostate cancer in 2009. The rate has been declining every year, with many more men now living with the disease.
Hormone therapy may be given – alone or alongside other treatments like radiotherapy – to stop the production of testosterone, which causes the cancer cells to grow. If the disease relapses after initial hormone treatment, it’s called castration-refractory prostate cancer (CRPC). The next step for men with CRPC is usually chemotherapy with docetaxel.
CRPC can spread to the bone, causing pain, fractures and other serious complications. There are various options available to treat the bone damage. These include drugs known as bisphosphonates such as zoledronic acid, and radioactive substances such as strontium-89.
Previous studies have suggested that adding the bone-targeting drugs zoledronic acid or strontium-89 to chemotherapy in men with CRPC may improve survival and reduce the risk of bone-related complications. This trial was funded by the NIHR to see if these drugs worked and, if so, if they were good value for money.
What did this study do?
This randomised controlled trial (TRAPEZE) assessed the effects of providing bone-targeting treatment with zoledronic acid or strontium-89 alongside docetaxel chemotherapy in men with CRPC.
A total of 757 men with CRPC that had spread to the bone were recruited from oncology departments across the UK.
Participants were randomly assigned to one of four treatment groups: docetaxel alone; docetaxel plus zoledronic acid; docetaxel plus strontium-89; or docetaxel plus zoledronic acid and strontium-89. The steroid prednisolone was given to all groups.
Participants were followed up for an average of 22 months to look at time to progression of bone-related complications, pain progression or death. The study also considered the cost effectiveness of the treatment combinations.
What did it find?
- Strontium-89 plus docetaxel and zoledronic acid plus docetaxel both increased time without bone-related complications, pain progression or death by about a month compared with docetaxel alone. This difference was not statistically significant for zoledronic acid, but was just technically significant for strontium-89 when adjusted for cancer score and study centre (hazard ratio [HR] 0.85, 95% confidence interval [CI] 0.73 to 0.99).
- When bone-related complications were considered separately, zoledronic acid increased the time until complications by more than two months compared with docetaxel alone (HR 0.78, 95% CI 0.65 to 0.95). It also reduced the total number of complications.
- Strontium-89 did not increase the time until bone-related complications compared with docetaxel alone.
- Neither treatment combination improved overall survival compared with docetaxel alone.
- Compared with docetaxel, strontium-89 cost an extra £16,590 for each year that the person lived a good quality of life. This cost falls just below the usual NHS willingness-to-pay threshold of £20,000 to £30,000 a year.
- Zoledronic acid cost an extra £42,047 per year of good quality life if the branded drug was used, but using the generic version brought the cost down to £8,005, suggesting this drug is a reasonable use of NHS resources.
What does current guidance say on this issue?
NICE guidance from 2006 recommends docetaxel for treating men with CRPC that has spread, providing that their cancer is not so serious as to require special or inpatient care.
NICE’s 2014 guideline on diagnosis and management of prostate cancer says that bisphosphonates should not be offered to prevent or reduce the complications of bone metastases in men with CRPC, but may be considered for pain relief when other treatments have failed.
It adds that strontium-89 should be considered for men with CRPC and painful bone metastases, especially those men who are unlikely to receive chemotherapy that suppresses bone marrow function.
What are the implications?
Though zoledronic acid was not effective at improving overall survival, it did prolong the time to any bone-related events. It was cost effective if using the non-branded version, and therefore may have some value in preventing bone-related complications and improving quality of life.
This study also supports the use of strontium-89 alongside docetaxel chemotherapy, in line with current NICE guidance, to improve quality of life for men with CRPC that has spread to the bone.
This study does not consider new radioactive treatments that have recently become available, such as radium-223. Further research may find these newer alternatives to be more clinically and cost effective for improving survival in men with metastatic prostate cancer.
Citation and Funding
James N, Pirrie S, Pope A et al. TRAPEZE: a randomised controlled trial of the clinical effectiveness and cost-effectiveness of chemotherapy with zoledronic acid, strontium-89, or both, in men with bony metastatic castration-refractory prostate cancer. Health Technol Assess 2016;20(53).
This project was funded by the National Institute for Health Research Health Technology Assessment (HTA) programme (project number 06/303/205).
Bibliography
Cancer Research UK. Prostate cancer incidence statistics. London: Cancer Research UK; 2015.
James ND, Pirrie SJ, Pope AM, et al. Clinical outcomes and survival following treatment of metastatic castrate-refractory prostate cancer with docetaxel alone or with strontium-89, zoledronic acid, or both: the TRAPEZE randomized clinical trial. JAMA Oncol. 2016;2(4):493-9.
NICE. Docetaxel for the treatment of hormone-refractory metastatic prostate cancer. TA101. London: National Institute for Health and Care Excellence; 2006.
NICE. Prostate cancer: diagnosis and management. CG175. London: National Institute for Health and Care Excellence; 2014.
Prostate Cancer UK. Advanced prostate cancer. London: Prostate Cancer UK; undated.
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