Summary
Over the last several years, there has been an increased interest in the US in particle beam therapy as the costs have come down and large manufacturers have become more efficient in installing these centers. In addition, private companies have made a business model of building proton centers - mostly by treating prostate cancer.
Protons are incredibly useful in specific diseases - ie ocular melanoma, pediatric cancers, but are too costly without proven benefit for our health care system.
Analysis
Over the last several years, there has been an increased interest in the US in particle beam therapy (namely proton beam therapy) as the costs have come down (marginally) and large manufacturers (IBA) have become more efficient in installing these centers. In addition, private companies (ProCure) have made a business model of building proton centers - mostly by treating prostate cancer.
While the theory of particle beam radiotherapy is quite elegant - ie having the ability to prescribe radiation to a depth in tissue and have no dose going beyond that point, the reality is that proton therapy also has many downsides.
First, many tumors are just not practically amenable to proton therapy - ie - tumors that have a lot of motion, or tumors where the volume can not be precisely well defined. In both of these cases the range modulation of proton therapy could potentially lead to undertreatment.
Second, the cost of delivery on a per fraction basis is quite high, and hence the private models salivate over the loads of prostate cancer cases they could treat. However, there is no way in the Obama era of containing costs in Medicare, that protons will continue to be reimbursed at such high rates - this would just bankrupt Medicare. In fact, in an era of comparative effectiveness, there are many more cost effective and equally efficacious treatment options in prostate cancer including iodine brachytherapy and IMRT/IGRT.
Third, there has never been any survival benefit associated with treating with protons compared with conventional modern radiotherapy series. While some would tout the side effect profiles are improved with protons, the reality is that the current side effects from conventional modern radiotherapy are quite tolerable, and there is not a tremendous amount of gain from protons. In fact in dose escalation with prostate cancer with IMRT, the rates of late rectal toxicity are as low with photons as protons. In lung cancer, we have never proven any survival benefit with dose escalation with conventional radiation, and would likely see no benefit with protons.
Yes - if we had all the money in the world to spend on healthcare, of course we'd all be using protons - don't get me wrong. But in a world where healthcare costs real dollars, massive proliferation of these expensive centers makes no sense, unless you are a private investor trying to make a profit - and if you go this route, you will soon learn that Medicare can very easily cut the reimbursement and destroy your business model.
This country does need protons, but it should be a thought out arrangement of regional centers - ie 15-20 and kept to a limited role for appropriate cancers until the costs of this technology can be brought in line with more conventional, equally efficacious therapies.
