Proton radiotherapy is more precise, helps achieve optimal dose distribution to the site, spares neighboring normal tissue, and thereby avoids unnecessary complications in patients. Now a new study in pediatric patients with medulloblastoma has found that with similar survival outcomes as conventional radiotherapy, the proton beam therapy (PBT) may prove less damaging to the child’s body than traditional radiotherapy.
The study, published in The Lancet Oncology
, reports on the results of a non-randomized, single-center, open-label phase 2 trial that enrolled 59 patients with medulloblastomas between May 20 2003 and December 10, 2009. Trial participants were between 3 and 21 years of age. All 59 patients had received chemotherapy, and the median follow-up (of survivors) was 7 years. The patients were delivered craniospinal irradiation of 18-36 Gy radiobiological equivalents (GyRBE) delivered at 1·8 GyRBE per fraction followed by a boost dose, the authors write. The primary outcome was cumulative incidence of ototoxicity at 3 years, graded with the Pediatric Oncology Group ototoxicity scale (0-4), in the intention-to-treat population. Secondary outcomes were neuroendocrine toxic effects and neurocognitive toxic effects, assessed by intention-to-treat.
During the follow-up period, 4 of 45 evaluable patients had grade 3-4 ototoxicity in both ears and 3 developed grade 3-4 ototoxicity in 1 ear, one of whom reverted to grade 2. The cumulative incidence of grade 3-4 hearing loss at 3 years was 12% (95% CI, 4-25) and 16% (95% CI, 6-29) at 5 years, the study reports. While the study found an average of 1.5 point reduction in the intelligent quotient (processing speed and verbal comprehension) of the patients every year during a 5.2 year median follow-up period, perceptual reasoning and working memory were retained close to normal. With a 5-year progression-free survival of 80% and 5-year overall survival of 80%, the results of the study are very promising.
Applauding the improved quality of life (QoL) promised by the results of this study, David R Grosshans, MD, PhD, a radiation oncologist with the MD Anderson Cancer Center writes in an accompanying commentary, “I believe that many in radiation oncology embrace new technology, not simply to have the latest and greatest innovations, but rather to reduce the effect of radiation therapy on patients’ quality of life. Nowhere in oncology is this more important than for pediatric cancers.” He adds that the current study conducted at Massachusetts General Hospital can set a new benchmark for treating young patients with medulloblastomas.
Payers Balk at the Cost of PBT
Payer push-back has been restricting the use of PBT and has also forced center closures, as was witnessed
with the closing of the proton therapy center at Indiana University Health.
A study published in 2012 in the Journal of the National Cancer Institute
evaluated Medicare reimbursement data comparing PBT versus intensity-modulated radiation therapy (IMRT) for prostate cancer—PBT cost Medicare $32,428 and IMRT cost $18,575.
Proponents of PBT argue that we should look beyond the front-loaded costs of treatment and think in terms of savings in downstream costs associated with improved patient QoL. “If a patient is suffering more side effects and you have to pay more for managing them that may override the cost on a day-to-day basis,” says
Steven J. Frank, MD, medical director of the MD Anderson Proton Therapy Center.
With time, the cost of building, housing, and running these facilities will eventually reduce, experts argue, as more centers are constructed and evidence builds to the advantages of PBT.
A proton model policy developed by The American Society for Radiation Oncology creates a framework researchers can use to communicate with third-party payers which patients need to be covered, according to Frank. “Third-party payers are struggling with advanced technologies like proton therapy because they are trying to control health care costs.” But, he says, researchers have a unique opportunity and responsibility to run clinical trials in order to answer important questions about the comparative effectiveness and value of PBT. The results of these clinical trials will help educate payers when it is medically necessary to treat cancer patients with proton therapy, he says.
According to The National Association for Proton Therapy, there are 20 operational PBT centers in the United States and 15 more are being developed.