Researchers conducting a phase I/II clinical trial of proton radiation for early prostate cancer found that the treatment is safe and well-tolerated by patients, but probably no better than other, less expensive forms of radiation. Their preliminary findings were presented at a meeting of the American Society for Therapeutic Radiology and Oncology in September 2008; subsequent findings were published online in 2010 in the International Journal of Radiation Oncology, Biology & Physics.
The study tested a total radiation dose of 82 Gray, slightly higher than the traditional dose of 78 Gray. Of the 84 patients included in the study, about two-thirds developed relatively minor genitourinary or gastrointestinal side effects, such as urinary incontinence, at the time of the treatment or shortly thereafter. Roughly the same number of patients developed problems in the months that followed, notably urinary frequency/urgency and rectal bleeding. Fewer than 10% of patients experienced more serious side effects. Initially, the median follow-up time was 23 months, but that time was extended to 31.6 months in the online report.
The study did not directly compare different types of radiation therapy. Nor did it assess patient outcomes, such as biochemical recurrence of disease, because the follow-up time was too short. But it does seem to indicate that a dose of proton radiation up to 82 Gray is relatively safe and tolerable for patients.
SOURCES: Zietman AL, Bae K, Coen JJ, et al. A Prospective Phase I/II Study Using Proton Beam Radiation to Deliver 82GyE to Men with Localized Prostate Cancer: Preliminary Results of ACR0312. International Journal of Radiation Oncology, Biology & Physics 2008;72(1 Suppl):S77. Abstract 169.
Coen JJ, Bae K, Zietman AL, et al. Acute and Late Toxicity After Dose Escalation to 82 GyE Using Conformal Proton Radiation for Localized Prostate Cancer: Initial Report of American College of Radiology Phase II Study 03-12. International Journal of Radiation Oncology, Biology & Physics 2010; e-publication. PMID: 20932675.
Originally published Jan. 1, 2009; Last reviewed April 11, 2011