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Proton therapy needs to prove itself against standard RT

Proton therapy needs to prove itself against standard RT

ABSTRACT: Modeling study calculates that the adoption of proton therapy is possible if it is based on clinical evidence and not market forces.

For devoted proponents of proton-beam therapy, the future looks pretty bright. A field that has been short on clinical data saw multiple studies presented at ASTRO 2009 in support of the technology that is lauded for its lower radiation dose and less toxicity (see "Proton-beam Rx reduces prostate cancer recurrence," January 2010, page 1).

Last month, the first batch of radiation therapists graduated from Ivy Tech Community College in Bloomington, Ind., with certificates to perform proton-beam therapy.

But a major question still looms over this technology: Is proton-beam therapy really better than standard radiotherapy? The Agency for Healthcare Research and Quality (AHRQ) posed this question and others in a 2009 report. The AHRQ technical brief surveyed the current evidence on proton-beam therapy and found that most studies did not include a direct comparison with other radiation-based treatment methods (Visit www.effectivehealthcare.ahrq.gov for the complete report).


Brain tumor treated with proton therapy. Less healthy tissue is exposed to radiation with proton therapy (gray/white area indicates no radiation exposure). Image courtesy of ProCure Training and Development Center and Sameer Keole, MD.

One of the coauthors of the AHRQ report, Tomas Dvorak, MD, set out to determine which factors—evidence-based medicine or market forces—will drive the utilization of proton-beam therapy in the future (see Related Reading on page 30).

Dr. Dvorak is a clinical instructor in radiation oncology at Tufts University School of Medicine in Boston. His study coauthors were David E. Wazer, MD, chairman of the department of radiation oncology at Tufts, and Markus Fitzek, MD, MSc, DABR, director of research and development at Midwest Proton Radiotherapy Institute in Bloomington.

Dr. Dvorak discussed the results of his group's current study with Oncology News International. He also offered his perspective on the emerging clinical evidence for proton-beam therapy and whether the technology will truly find a place in the radiation oncology armamentarium.

ONI: Looking at the numbers generated by your study, it would seem that the cost of adopting and deploying proton-beam therapy is quite high. At the present time, do the costs outweigh the benefits?

Dr. Dvorak: You have to put the costs into perspective, and cost is relative. Look at what some of the costs are in medical oncology. What's the cost of putting patients on a maintenance chemotherapy regimen with rituximab (Rituxan) for eight or nine years? As radiation oncologists, we get a bit nervous when people look at our costs out of context.

Yes, the cost is high for proton therapy, but there are two components to the cost. First, there is the capital expenditure for buying the machine and building the facility to house it. That doesn't directly impact spending on healthcare.

Then there is the cost for actual treatment delivered. The fact is that the cost of proton treatment per fraction is higher than the cost of photon treatment per fraction. But using proton therapy in a reasonable fashion may not be that expensive. Based on our study, it only added 15% more on top of the normal budget for radiation therapy delivery.

Whether proton therapy is worth the cost also depends on the disease site. For instance, in pediatric patients with brain tumors or in a woman in her 30s with lymphoma, the consensus is that using proton therapy is meaningful. But is it meaningful for an 80-year-old man with prostate cancer?

At this point, we don't know for whom proton therapy is clinically superior. For our study, we made a judgment based on our clinical understanding of proton therapy and photon therapy to determine which patients we think would benefit. But there are very little actual data to drive these decisions, as demonstrated in our AHRQ study.

ONI: What about the two studies presented at ASTRO 2009 that offered encouraging results for proton-beam therapy in prostate cancer? Investigators at Loma Linda University in California determined that adding a proton boost to conventional radiation reduced the risk of recurrence (abstract 22) while a group from the University of Florida found that proton therapy was well tolerated by prostate cancer patients (abstract 23).

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