Only Short-Term Advantage for Protons in Prostate Cancer
AT THE ANNUAL MEETING OF THE AMERICAN SOCIETY FOR RADIATION ONCOLOGY
Dr. Gray acknowledged that the retrospective nature of the study and the use of different scoring instruments muddy the comparison waters. He noted that things may become clearer when the results of a recently launched randomized trial comparing PBT and IMRT become available. The study will look at 6-month efficacy outcomes, cost effectiveness, and toxicities at 2 years, and survival and other end points out to 10 years.
Protons Are a Costly Choice
Although the relative long-term benefits of PBT for prostate cancer may not be known for several years, one thing is sure: PBT is about 70% more expensive than IMRT, said Dr. James Yu, a radiation oncologist at Yale University in New Haven, Conn.
Dr. Yu and colleagues looked at data on patients who received IMRT or PBT as primary therapy for prostate cancer in the Medicare Chronic Condition Data Warehouse, a national database that captures 100% of Medicare fee-for-service claims for patients with specific chronic conditions.
They found that the median interquartile range amount that Medicare reimbursed for PBT was $32,428 vs. $18,575 for IMRT.
In early follow-up (0-6 months) genitourinary complications were significantly lower among 421 patients with who had received PBT than among 842 patients who received IMRT (5.9% vs. 9.5%; odds ratio 0.60; P = .03). Neither gastrointestinal nor other complications were significantly different, however, and at 12 months follow-up there were no significant differences between treatment types, Dr. Yu noted.
"A continued longitudinal study of the comparative effectiveness of proton radiation is needed, and we also believe that further study is needed before widespread application of proton radiation can be justified," he said.
PBT Benefit Proven in Other Cancers
A radiation oncologist who was not involved in the study commented that in the absence of evidence of a therapeutic benefit for PBT in prostate cancer over other modalities, proton therapy may better be reserved for the treatment of other cancers.
"If you have a resource that’s limited, you want to use it where you know there’s a benefit," said Dr, Jeffrey Bradley, professor of radiation oncology at Washington University in St. Louis.
His center is building a single-vault proton-beam facility that is expected to open in the summer of 2013. Dr. Bradley said that although they will likely treat patients with prostate cancer, he envisions the main role of the center to be treatment of pediatric and adult tumors of the central nervous system, sarcomas, ocular neoplasms, and other conditions where the benefits of PBT are better documented.
Dr Gray, Dr. Yu, and Dr. Bradley each reported no conflicts of interest.
