To the Editor: We believe that the article “Proton Therapy in an Era of Cost Containment” by Joseph M. Herman, MD, in the August 2011 issue (JNCCN 2011;9:821-825) fails to adequately address the problems that this radiation modality presents to the medical community and society as a whole. Consider that: Sharply defined dose distributions and reduced integral doses are the stock-in-trade of proton beam therapy (PBT), however, proton beam dose distributions are more readily talked about than achieved. A proton's depth of penetration is a function of its energy and inversely proportional to the densities of intervening tissues. For example, to make the spread-out Bragg peak from opposed lateral fields bracket the prostate, the exact depth of the prostate for each field must be known; a slight asymmetry might require the maximum energy of the right lateral field to be higher or lower than that for the left. For each patient, compensating filters must be constructed that control the depth of penetration and also consider depth reductions caused by the femoral heads and those parts of the femurs included in each field.
Additionally, although the spread-out Bragg peak can be made to conform to the distal surface of the tumor, it cannot simultaneously conform with the proximal surface. Where the anatomy is intricate (e.g., skull-base or lung), designing compensating filters becomes increasingly more difficult, and conforming the spread-out Bragg peak with the tumor volume increasingly more uncertain.1
Minor variations in patient positioning have a disproportionately larger effect on proton dose distributions than on x-rays. Because x-rays exit the distal side of the patient, electronic portal imaging is routinely used to confirm that the beams are properly positioned. However, because proton beams terminate within the patient, there is no practical way of confirming that the spread-out Bragg peak coincides with the tumor. For this reason, and for that given in the preceding paragraph, the usual practice in radiation therapy of making planned dose distributions larger than the perceived tumor volumes has carried over to PBT. Any suggestions of millimeter accuracy in PBT must be taken with a large grain of salt.
Because any differences in clinical out-comes between PBT and more conventional modalities are likely to be small, the number of patients enrolled in a randomized clinical trial of, for example, early-stage non-small cell lung cancer would have to be counted in the hundreds. Such trials are expensive and, in most cases, take years to complete. The same would apply to childhood cancers, which advocates suggest is one of PBT's strong points. However, for childhood cancers such as ependymomas, low accrual rates all but preclude a clinical trial even getting started.
Medicine is a humanitarian discipline, a melting pot of science, common sense, and compassion in which one person attempts to relieve the pain and suffering experienced by another. Throughout history, payment for services rendered was mainly determined in the marketplace, with the level of reimbursement only casually related to the quality of care. The introduction of health insurance and Medicare has, to a great extent, leveled the playing field, however, although there are still great disparities in cost for treatments that yield similar results. The commercial availability of PBT systems over the past decade has been a game changer in this respect because their $150 to $200 million price tags are generally beyond the means of most hospitals and physicians. With guidance from the manufacturers, funds for PBT centers have been raised from venture capitalists, pension funds, and banks, among others: organizations seeking returns that equal, or preferably exceed, those available from more conventional investments.
With profits to share holders now a dominant component of a PBT facility's business plan, economic sustainability requires a level of patient throughput sufficient to meet the projected bottom line. Therefore, more expensive treatments for a wide range of disease sites yielding results no better than those obtained by more conventional treatments are standard practice. Has predatory capitalism, long rampant in the pharmaceutical industry, now moved into radiation oncology?
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Brada M, Pijls-Johannesma M, De Ruysscher D. Proton therapy in clinical practice: current clinical evidence. J Clin Oncol 2007;25:965-970.
Lodge M, Pijls-Johannesma M, Stirk L. A systematic literature review of the clinical and cost-effectiveness of hadron therapy in cancer. Radiother Oncol 2007;83:110-122.
Olsen DR, Bruland OS, Frykholm G, Norderhaug IN. Proton therapy—a systematic review of clinical effectiveness. Radiother Oncol 2007;83:123-132.