A recent study by Hoppe et al concludes:
Although the benefits to patients of reduced radiation-dose exposure with PT are quite obvious, concerns still exist regarding whether these dosimetric benefits are cost-effective. In a study by Konski et al,... the cost-effectiveness of PT was compared to that of IMRT with the assumption that PT could deliver a 10-Gy higher dose than IMRT, resulting in a 10% improvement in 5-year BFFS compared with IMRT. However, despite the improvement in BFFS, the resulting cost of PT for a 60-year-old man was $65,000, compared with $40,000 for IMRT, which would result in a cost-effectiveness of $56,000 per quality-adjusted life year (QALY). When compared to the commonly accepted standard of $50,000 per QALY, the value for PT indicated that it was not cost-effective. Although this study reaches some intriguing conclusions, the results are based on models and do not take into consideration a number of critical factors. First, Peeters et al... have predicted that PT may allow for hypofractionation, which would reduce the treatment costs of this therapy. Studies currently investigating hypofractionation with PT are ongoing at both Loma Linda University and the University of Florida Proton Therapy Institute. Second, a reduction in significant rectal and urinary toxicity afforded by PT will have a positive impact on overall costs of care in prostate cancer patients. Finally, the dose escalation and dose intensification via hypofractionation permitted by PT may result in increased cure rates, particularly in intermediate and high-risk prostate cancer patients,... which may also translate into reduced costs of care.
Namely it is a costly procedure. This has always been a concern. Proton machines are tens of millions, approaching in excess of 100 million, and thus are often prohibitive. They work well for certain childhood malignancies and in uveal melanomas of the eye. However there are still major clinical concerns.
The clinical conclusions of the paper state:
With a minimum follow-up of 2 years, the grade > 3 GU toxicity rate was 1.9% and the grade > 3 GI toxicity rate was <0.5%. Two studies out of Japan have also published early outcomes for PT for prostate cancer. Mayahara et al reported on 287 patients treated to 74 CGE with 190- to 230-MeV protons using opposed lateral fields; the rate of grade > 3 GU toxicity in this study was 1%, and the rate of grade > 3 GI toxicity was 0%. Nihei et al[30] reported on a multi-institutional phase II study from Japan in which 74 CGE was delivered in 37 fractions in 151 patients. With a median follow-up of 43 months, only 1% of patients developed grade > 3 GU toxicity, and 0% developed late grade > 3 GI toxicity. These studies, which are reported in the Table, confirm the safety of PT for prostate cancer over the first 4 years following treatment; however, longer follow-up is needed to confirm the low rate of late toxicity and long-term efficacy of the treatment (and the high rate of BFFS). Interestingly, Massachusetts General Hospital and Loma Linda University have reported a smaller series of patients treated with PT alone to 82 CGE, with a slightly higher rate of toxicity than observed in the University of Florida Proton Therapy Institute series with the same dose and dose per fraction.
It appears as if there is still an open issue here. More clinical trials are needed. Yet the clinical progress seems to be moving forward.
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