Results from the largest study of men with clinically localized prostate cancer treated with high-dose, intensity-modulated radiation therapy show that the majority are alive without evidence of disease after an average follow-up of eight years, according to an article in the October issue of the Journal of Urology.

Between April 1996 and January 2000, 561 patients with a median age of 68 years (range, 46 to 86 years old) were treated with intensity-modulated radiation therapy, an improved form of three-dimensional conformal radiation therapy, at Memorial Sloan Kettering Cancer Institute.

Pre-treatment diagnostic evaluations were performed for all patients to better define their clinically localized prostate cancer. They were classified into prognostic risk groups as defined by the National Comprehensive Cancer Network guidelines. Clinical characteristics that were weighed included age, T stage, Gleason score, prostate-specific antigen level, and pre-treatment with neoadjuvant androgen deprivation.

The eight-year results show urinary continence was maintained in all patients, and only 9 (1.6 percent) patients experienced rectal bleeding. Radiation therapy was curative for the majority of the patients in all three prognostic risk groups, with 89 percent of the favorable, 78 percent of the intermediate, and 67 percent of the unfavorable group alive after an average of eight years. Among men who were potent prior to therapy, erectile dysfunction developed in 49 percent.

This report is the first description of long-term outcomes for prostate cancer patients treated with that therapy.

“Our results suggest that intensity-modulated radiation therapy [IMRT] should be the treatment of choice for delivering high-dose, external beam radiotherapy for patients with localized prostate cancer,” said Michael J. Zelefsky, MD, Chief of the Brachytherapy Service at Memorial Sloan-Kettering.

“We were able to show long-term safety and long-term efficacy in a very diverse group of prostate cancer patients that we followed ? many for as long as ten years. Despite the fact that some patients had an aggressive form of disease with high Gleason scores and prostate specific antigen levels, the overwhelming majority had good tumor control with neither recurrence of their original cancer nor development of second cancers, which one might have expected from the high doses of radiation.”

“This study confirms that we can improve patients’ quality of life by reducing the side effects of radiotherapy while maintaining disease-free survival,” said Zelefsky. “However, there is still room for improvement. We are incorporating image-guided approaches that may continue the excellent tumor control but further limit the area we are irradiating and reduce side-effects."