Volumetric Modulated Arcs and Intensity Modulated Proton Therapy Improve Conformal Avoidance in Prostate Cancer

Volumetric modulated arcs (RA) and intensity modulated proton therapy (IMPT) proved superior to fixed intensity modulated radiation therapy (IMRT) in sparing organs and improving tumor coverage for patients with recurrent prostate cancer in a recent study Radiation Oncology.

The Swiss researchers optimized plans for seven patients with a prescribed dose of 56 Gy in 14 fractions. Recurrent gross tumor volume (GTV) was determined by 18Ffluorocholine PET/CT scans, according to the authors in an article titled "RapidArc, Intensity Modulated Photon and Proton Techniques for Recurrent Prostate Cancer in Previously Irradiated Patients: A Treatment Planning Comparison Study."

The study included a maximum dose of 61.6 Gy to 5 percent of the GTV, with the urethra constrained to 36 Gy and the rectal D_Median at 17 Gy. Damien C. Weber et al. analyzed the results using dose-volume histogram and conformity index parameters.

RA improved tumor coverage when compared to IMRT, with intermediate values for IMPT. Both RA and IMPT significantly decreased the percentages of rectal and urethral volumes that received intermediate doses, according to the study published online at http://www.ro-journal.com/content/4/1/34.

"RA and IMPT showed improvements in conformal avoidance relative to fixed beam IMRT for seven patients with recurrent prostate cancer," concluded the authors. "IMPT showed further sparing of organs at risk."