by ecancer reporter Clare Sansom

Prostate cancer is the most frequently diagnosed cancer in males in the UK and other developed countries. Radiotherapy is a very common treatment for this tumour, with three-dimensional conformal radiotherapy (3DCRT) the current standard of care. Intensity modulated radiotherapy (IMRT) allows the tumour tissue to be targeted more exactly, thus reducing the radiation dose delivered to surrounding normal tissue and, potentially, reducing toxicity. It is, however, more expensive than 3DCRT.

Silvia Hummel and her co-workers, based at the University of Sheffield, UK, conducted a systematic literature review comparing the clinical and cost effectiveness of IMRT in prostate cancer to that of 3DCRT. The patient groups studied were those for which radiotherapy is an appropriate treatment, and specifically, men whose tumours were localised to the prostate capsule or locally advanced. The researchers evaluated the two treatments for overall and progression-free survival, side effect profile and quality of life, and estimated the incremental cost-effectiveness of IMRT compared to the current standard of care. Eight relevant full studies published in peer reviewed journals before May 2009 were identified for inclusion in the review; six of these were on localised and two on locally advanced prostate cancer. A larger number of relevant conference abstracts were identified, and these were included in the analysis although they contained much less detail. No randomised controlled trials of the two radiotherapy regimens were identified; all included studies were comparative in nature. Four further cost-utility studies of the two regimens were identified.

Only one of the studies – a conference abstract – used overall survival as a comparator. Most studies compared biochemical relapse-free survival, based on PSA levels; of these, only one showed improved relapse-free survival with IMRT, and that involved a higher dose of IMRT than of 3DCRT. The authors therefore concluded that there was no evidence that the restricted-field treatment regimen improved survival rates. However, most studies indicated that patients treated with IMRT had less toxicity, and particularly less late gastro-intestinal toxicity, than those treated with 3DCRT.

The excess cost of treating a patient with IMRT against 3DCRT in the UK was estimated to be £1100. The cost-effectiveness of the regimens was modelled using four different scenarios with varying differences in survival and toxicity. In the two scenarios that modelled a slight increase in survival with IMRT, that regimen was found to be cost-effective. If, however, the only difference between the treatments was taken to be in toxicity and thus in quality of life (which seems most likely), the incremental cost-effectiveness ratio was shown to depend greatly on the magnitude of that difference in toxicity. It cannot yet be concluded that IMRT is, or is not, more cost-effective than 3DCRT. Hummel and her colleagues concluded that further research, particularly randomised controlled trials, is needed before this question can be answered.

Reference

Hummel, S., Simpson, E.L., Hemingway, P., Stevenson, M.D., and Rees, A. (2010). Intensity-modulated radiotherapy for the treatment of prostate cancer: a systematic review and economic evaluation. Health Technol Assess 14(47). DOI: 10.3310/hta14470