High Dose 3D Conformal Radiotherapy of Prostate Cancer Using Spaceoar Gel

Abstract

The aim of this study was to investigate the applicability of high dose radiation therapy following the administration of SpaceOar Hydrogel to decrease rectal toxicity in patients with prostate cancer who had received definitive three-dimensional conformal radiation therapy. Seven patients with a diagnosis of prostate cancer received, under general anesthesia, 10 ml of prostate SpaceOar hydrogel injections transperineally into the space between the prostate and the rectal front wall under the guidance of transrectal ultrasonography. Abdominal tomography and magnetic resonance images of the patients were taken before and after the application of hydrogel. Using both imaging sets and similar algorithms, 3D conformal radiotherapy plans were made that aided in making the calculations. The radiation dose to be applied was calculated from the dose-volume histograms of the target and at risk organs of the patients with tailor-made plans. In the treatment of prostate cancer patients with and without hydrogel plans, there was a statistically significant difference between the rectal V70 and V50 doses, which were 20% ± 14.9 vs 11% ± 2.2 ( p:0.002), and 34 ± 7.9 vs 28.2 ± 11 (p: 0.048), respectively. The D95 and D5 values were similar in all patients with and without hydrogel plans. Rectal toxicity decreased in patients with a distance of >15 mm (p=0.053). Consequently 3D conformal radiotherapy can be successfully and safely applied at high dose with low toxicity to prostate cancer patients after placing hydrogel between the rectum and prostate.

Keywords: Prostate cancer, radiotherapy, spaceoar hydrogel, rectal toxicity

DOI: 10.7176/JSTR/5-6-08