Study: IMRT bests conventional therapy for prostate cancer

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Highly contoured intensity-modulated radiotherapy (IMRT) may be a successful strategy for reducing morbidity in prostate cancer treatment, as patients involved were found to have less radiotherapy related morbidity than their counterparts treated with conventional target volume margins, based on study findings published online Feb. 16 in Urology.

In the study, Howard Sandler, MD, from the department of radiation oncology at Cedars-Sinai Medical Center in Los Angeles, and colleagues investigated whether patients who received high-dose external beam IMRT for decreasing target volume margins while using real-time tumor tracking (Calypso Medical) for the treatment of their prostate cancer would report a higher quality of life post-treatment than patients who underwent treatment involving traditional margins.

The researchers used the prospective, multicenter study, Assessing Impact of Margin Reduction (AIM) trial, and compared the AIM study group of 64 patients to 153 patients in a comparator study published in the New England Journal of Medicine in 2008.

While the 64 patients in the AIM cohort were found to have reported less favorable clinical characteristics than the 153 comparator patients, AIM patients receiving radiotherapy were found to have had less bowel morbidity than the comparator group from pre-treatment to post-treatment, wrote the researchers. Of the 217 patients, 64 study participants underwent IMRT with a nominal dose of 81 Gy in 1.8-Gy fractions to the prostate and proximal seminal vesicles, using uniform 3 mm planning target volume margins with electromagnetic real-time tracking.

The researchers assessed morbidity before and two months after the end of radiotherapy using Expanded Prostate Cancer Index Composite (EPIC) questionnaires, which were completed via telephone or administered in written test form to patients while at the clinics. Changes in scores were compared between the AIM study cohort with a post-treatment questionnaire response rate of 89 percent and the comparator cohort who had been treated with conventional margins and had a response rate of 97 percent.

Based on the results of the self-reported EPIC questionnaires, the researchers also concluded that the AIM study patients experienced clinically relevant treatment- related worsening of symptoms in only one health-related quality of life domain (urinary) whereas decline in three health-related quality of life domains (urinary, sexual and bowel/rectal) was reported in the comparator cohort.

“Reducing the PTV margin is an attractive option when prostate motion can be carefully managed during daily radiation treatment, as this reduction can result in decreased acute treatment-related adverse effects," wrote the authors. “Margin reduction is a logical step in the evolution of IMRT and may support radiotherapy strategies that contribute to better long-term outcomes.”

The study was originally presented at the 51st annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in November 2009.