Impact of post-implant dosimetric parameters on the quality of life of patients treated with low-dose rate brachytherapy for localised prostate cancer: Results of a single-institution study

Abstract

Background: To assess the relationship between dosimetric parameters and the quality of life (QL) outcomes of patients with low-intermediate-risk localised prostate cancer (LPC) treated with low-dose-rate brachytherapy (LDR-BT). Materials and methods: We evaluated the participants in two consecutive prospective studies of the QL of patients treated with LDR-BT for LPC. QL was evaluated by means of a patient-completed questionnaire assessing non functional [physical (PHY) and psychological (PSY) well-being, physical autonomy (POW), social relationships (REL)] and functional scales [urinary (URI), rectal (REC), and sexual (SEX) function]; a scale for erectile function (ERE) was included in the second study. Urethra (D10≤210 Gy) and rectal wall constraints (V100≤0.5 cc) were used for pre-planning dosimetry and were assessed with post planning computerized tomography one month later for each patient. Results: QL was assessed in 251 LPC patients. Dosimetry did not influence the non-functional scales. As expected, a progressive impairment in sexual and erectile function was reported one month after LDR-BT, and became statistically significant after the third year. Rectal function significantly worsened after LDR-BT, but the differences progressively decreased after the 1-year assessment. Overall urinary function significantly worsened immediately after LDR-BT and then gradually improved over the next three years. Better outcomes were reported for V100 rectal wall volumes of≤0.5 cc and D10 urethra values of≤210 Gy. Conclusions: The findings of this study show that dosimetric parameters influence only functional QL outcomes while non-functional outcomes are only marginally influenced.