In Physics Today’s October 2015 Readers’ Forum (page 8), Robert Schulz and A. Robert Kagan take the stance that there is no justification, in terms of cost or clinical benefit, for the development of carbon-ion therapy (CIT). Schulz and Kagan argue that the case for using proton-beam therapy (PBT) over intensity-modulated radiation therapy (IMRT) has not been made, and they then extrapolate that to CIT.

Comparing PBT to IMRT is inappropriate. Comparing intensity-modulated proton therapy to IMRT would provide more insight. Early adopters of proton therapy used passive scattering methods for dose delivery; they did not have the capability for intensity-modulated protons that they do now. Indeed, PBT clinical trials with scanning beams and better tumor localization via in vivo computed tomography imaging are ongoing. Yet centers with such systems are finding it difficult to overcome the mind-set, based on earlier, inappropriate comparisons, that questions the value of PBT.

Schulz and Kagan indicate that PBT is the result of physicists who were bored with cyclotron technology and that CIT is more of the same. They mention the start of CIT at the GSI Helmholtz Centre for Heavy Ion Research in Germany in 1997, yet they miss the initial clinical trials with heavy charged particles that included helium, carbon, and neon at the Lawrence Berkeley Laboratory between 1977 and 1992 and the earlier work at the National Institute of Radiological Sciences in Japan. The NIRS started CIT clinical trials in 1994 based upon the results of the Berkeley trials. The NIRS has now treated more patients by far than any other institution. Their success has led to an additional six CIT centers in Japan alone.

To suggest that clinical trials for CIT will probably never be carried out belies the truth; the NIRS and other CIT institutions in Japan have set up the Japan Carbon Ion Radiation Oncology Study Group to conduct clinical trials. The Heidelberg and Marburg Ion-Beam Therapy Centers in Germany and the National Center of Oncological Hadrontherapy in Italy run clinical trials. In the US, the National Cancer Institute (NCI) has taken steps to develop CIT research institutes through two exploratory grants. After the impressive early results seen at the NIRS, the NCI is funding a clinical trial of IMRT versus CIT for pancreatic cancer, to be conducted in Shanghai, China, in collaboration with Albert Einstein College of Medicine.

The authors also argue that the cost does not justify the benefit; they use the example of PBT and extrapolate it to CIT. Construction of a PBT facility no longer requires government support. Yes, the up-front cost is higher for PBT or CIT than for IMRT, but a PBT or CIT facility can be amortized over 25–30 years as opposed to the 7–10 years for IMRT.

The 60-fold cost difference that Schulz and Kagan claim is just not credible. A recently constructed Japanese CIT facility with four treatment rooms cost approximately $100 million compared with $10 million to equip four rooms for IMRT. Furthermore, in 2014 the anticancer drugs bevacizumab and cetuximab cost $9324 and $20 856, respectively, for a single eight-week cycle, and bevacizumab sales were more than $6.8 billion. If Medicare and insurance or other payers allow an expenditure of $250 000 for a cancer therapy that extends life by 12 months, how can one lament a therapy that will be in line with or less than some medical oncology charges (the NIRS charges $30 000 for CIT therapy)? There is no reimbursement rate in the US for CIT; however, CIT therapy is highly effective and can be exquisitely targeted, so the number of treatments required per patient has dropped. Indeed, a CIT single-dose clinical trial for lung cancer is ongoing at the NIRS. Reducing treatment number and overall duration will dramatically contain costs.

Delaying construction of CIT facilities in the US until clinical results from existing facilities justify costs is not supported by the arguments in Schulz and Kagan’s letter. Facility costs have dropped substantially, and highly promising clinical results warrant further investigation and independent validation. The potential for CIT to overcome the challenge of tumor radioresistance—which limits the efficacy of photon and proton therapies—whether by overcoming hypoxia or by overcoming the genetic mechanisms of tumor radioresistance via a truly increased relative biological effectiveness is not just marginal enhancements as described by Schulz and Kagan. Furthermore, the potential for CIT plus immunotherapy, reduced adverse normal tissue responses, and improved quality of life after therapy are just some of the potential advantages we can expect from CIT. Academic CIT facilities with robust basic, preclinical, and clinical research capabilities are required. Such centers should be capable of implementing new engineering and physics enhancements and should be considered national resources.

We cannot emphasize this point more strongly: For those of us proposing to implement CIT, the history of justifying PBT is one of caution and a path to be avoided, not followed. And finally, CIT originated in the US. Now is the time for its return.