As with all emerging technologies, the publication of peer-reviewed research papers supporting the validity and effectiveness of proton therapy began modestly. An online search of the literature revealed 818 citations in 1990. However, this is changing: By 2000, the list had grown to 2,496 studies and by 2010, to 6,200 studies.
Some proton therapy experts were asked to identify a recently published paper of noteworthy clinical significance. Here are summaries of three of the studies and brief commentaries from the experts.
Here is the paper selected by Sameer Keole, M.D. from the ProCure Proton Therapy Center in Oklahoma City, Oklahoma City, Oklahoma.
“Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from Proton Radiation Oncology Group/American College of Radiology 95-09.” by Zietman AL, Bae K, Slater JD, Shipley WU, Efstathiou JA, Coen JJ, Bush DA, Lunt M, Spiegel DY, Skowronski R, Jabola BR, Rossi CJ (J Clin Oncol. 2010; 28(7): 1106-11)
Study summary: Long-term results: prostate cancer
Early-stage prostate cancer patients (n=393) were treated with conformal photon therapy to a fixed dose of 50.4 Gy followed by a proton-beam boost dose of either 19.8 Gy (conventional dose) or 28.8 Gy (high dose). The median follow-up of patients was 8.9 years.
In this randomized trial, high-dose external proton beam radiation therapy provided better long-term cancer control than did conventional-dose proton beam radiation therapy in men with localized prostate cancer. Dose escalation to 79.2 Gy was safely achieved without an increase in late urinary or rectal morbidity. These findings show that patients receiving a high-dose boost following conformal photon therapy will more likely be free from an increasing PSA 10 years later and less likely to require additional cancer therapy.
“The PROG 95-09 data certainly support the use of Proton Therapy for the treatment of prostate cancer. Of the six-dose escalation studies that have been published, it remains the only one that used a Proton Therapy component. Its inclusion allowed for safe dose escalation without an increase in rectal toxicity. It speaks volumes about the value of Proton Therapy”, says Sameer Keole, M.D. from the ProCure Proton Therapy Center in Oklahoma City, Oklahoma City, Oklahoma.