Inverse planning in high-dose rate brachytherapy improves quality of life of prostate cancer patients compared with forward planning.

Abstract

To understand differences in quality of life outcomes between cases with forward planning and cases with inverse planning, we examine patients undergoing high-dose rate brachytherapy combined with external beam radiotherapy for localized prostate cancer. We prospectively identified 283 patients with localized prostate cancer and divided them into forward planning and inverse planning groups. We extracted data on doses to the prostate, rectum and urethra that could potentially affect quality of life. We also evaluated quality of life using the Japanese version of Medical Outcome Study 8-Items Short Form Health Survey and Expanded Prostate Cancer Index Composite at pre-treatment and at 3, 6, 12 and 24months after treatment. Wilcoxon signed rank test and Bonferroni correction were used to analyze the irradiation dose and any change in quality of life. Doses to the prostate and rectum were not significantly different between the two groups. Notably, however, doses to the urethra were significantly lower in the inverse planning group than in the forward planning group. Patients in the forward planning group had significantly poorer physical component summary scores at 3months according to survey results. In Expanded Prostate Cancer Index Composite, patients in the forward planning group had statistically significant poorer urinary, bowel and sexual scores than those in the inverse planning group. Quality of life related to decline in sexual function was significantly reduced in the inverse planning group. Inverse planning in high-dose rate brachytherapy could significantly improve quality of life of patients with prostate cancer.