Benefits of proton therapy for prostate cancer patients are well established
The California Technology Assessment Forum (CTAF) today published its evaluation of proton beam radiotherapy technology for treating patients with prostate cancer. The CTAF uses the following five criteria to evaluate new and emerging medical technologies:
1. The technology must have final approval from the appropriate government regulatory bodies.
2. The scientific evidence must permit conclusions concerning the effectiveness of the technology regarding health outcomes.
3. The technology must improve net health outcomes.
4. The technology must be as beneficial as any established alternatives.
5. The improvement must be attainable outside the investigational setting.
In its assessment, the CTAF concluded that proton beam therapy meets the standards outlined in criteria 1-3, but does not satisfy criteria 4-5.
Scripps Health strongly disputes the CTAF’s assessment of criteria 4-5, for the reasons outlined below. Carl J. Rossi, Jr., M.D., medical director of the Scripps Proton Therapy Center, is available for news media interviews on this topic.
Criterion 4: The technology must be as beneficial as any established alternatives. Proton beam technology unquestionably satisfies this benchmark.
In its assessment, the CTAF failed to include the comprehensive assessment of equivalent benefit that was addressed by the American College or Radiology (ACR) in 2011, when an expert review panel was commissioned to evaluate the role of radiation therapy in treating Stage T1 and T2 prostate cancer. The ACR expert panel examined available peer-reviewed literature on this topic and concluded that proton beam therapy is equally appropriate and beneficial to intensity-modulated radiation therapy (IMRT), 3-dimensional conformal X-ray therapy and brachytherapy in the treatment of Stage T1 and T2 prostate cancer 1.
Further, it is ethically concerning that the CTAF persists in citing the relative lack of prospective randomized data supporting the use of proton beam therapy. Dose distributions of proton therapy are superior to photons – protons deliver two to three times less energy to normal, healthy tissue. A randomized controlled trial comparing photons to protons would require researchers to expose patients in the photon therapy group to normal tissue radiation. In view of the evidence that all radiation is harmful, it would be unethical to design a study wherein half of the participants would be receiving two to three times more radiation to normal tissue with no expected clinical benefit. When a technology is developed that allows clinicians to reduce normal tissue radiation dose, it has been rapidly accepted by the radiation oncology community without first having to prove itself in a randomized trial 2.
While the CTAF panel that assessed proton beam technology did not include a radiation oncologist, it did include an expert consultant who provided professional medical guidance: radiation oncologist Mack Roach III, M.D., who serves as professor and chairman of the Department of Radiation Oncology at the University of California, San Francisco. In his testimony before the CTAF panel, Dr. Roach clearly stated that proton beam therapy was every bit as beneficial as other established alternatives. The CTAF panel’s assessment of proton beam therapy contradicts the counsel of its own expert physician consultant.
Finally, the CTAF’s decision on criterion 4 relied largely on a study published earlier this year in the Journal of the American Medical Association. In this study, researchers at the University of North Carolina reached what Scripps believes are misguided conclusions that proton therapy treatment is no more effective than IMRT in treating prostate cancer – and that proton therapy is more likely to cause adverse bowel issues than IMRT. Scripps believes the methodology of this research is seriously flawed. For example, the study made no distinction regarding the total radiation dose given to the proton patients vs. the IMRT patients. No effort was made in the study to evaluate the possible differences in treatment planning and treatment delivery between proton and IMRT patients. And there were important differences in patient follow-up protocols between the two study arms.
The efficacy and safety of proton beam therapy for prostate cancer is well established. With Dr. Rossi as senior author, Loma Linda University has published long-term follow-up of its prospective experience in treating prostate cancer patients with proton therapy since 1991 3. Since then, many other groups have published reports on their experience using protons.
Criterion 5: The improvement must be attainable outside the investigational setting. Proton therapy is not investigational. Proton therapy is available to patients in both hospital-based settings and also through private institutions such as ProCure. Currently there are 10 proton therapy centers in operation in the United States, with 10 more either under construction or in development.
Joining physicians from Scripps Health and UCSF in speaking in favor of proton therapy at the CTAF hearing were physicians from MD Anderson Cancer Center, Mayo Clinic and Loma Linda University Medical Center.
1. Moran, B.J., et al., ACR Appropriateness Criteria® definitive external beam irradiation in stage T1 and T2 prostate cancer, Am J Clin Oncol, 2011. 34(6): p. 636-44
2. Suit, H., et al., Should positive phase III clinical trial data be required before proton beam therapy is more widely adopted? No. Radiother Oncol, 2008. 86(2): p. 148-53.
3. Slater, J.D., Rossi, CJ, Jr., Yonemoto, L.T., et al., Proton therapy for prostate cancer: the initial Loma Linda University experience, Int J Radiat Oncol Biol Phys, 2004. 59:348-352.
- Stephen Carpowich