Chronological changes of lower urinary tract symptoms after low-dose-rate brachytherapy for prostate cancer using SpaceOAR® system.

Background: The aim of this study is to investigate chronological changes of lower urinary tract symptoms (LUTS) in patients with prostate cancer who underwent low-dose-rate brachytherapy (LDR-BT) followed by the insertion of SpaceOAR® system (SpaceOAR).

Methods: In this retrospective study, 483 patients with localized prostate cancer underwent LDR-BT at the Gifu University Hospital between August 2004 and December 2020. SpaceOAR was inserted in 30 patients after LDR-BT (SpaceOAR group), and 453 patients received LDR-BT alone (non-SpaceOAR group). The International Prostate Symptom Score (IPSS), Overactive Bladder Symptom Score (OABSS), quality of life due to urinary symptoms (IPSS-QOL), and uroflowmetry (UFM), including maximum flow rate (Qmax), voided volume, and post-voided residual urine (PVR), were evaluated before LDR-BT, and at 1, 3, 6, 9, and 12 months after LDR-BT. The outcomes were chronological changes in IPSS, OABSS, and IPSS-QOL compared to pretreatment values and those of covariates in relation to UFM.

Results: The IPSS, OABSS, IPSS-QOL, Qmax, and voided volume were not significantly associated with either group. According to the PVR interaction effect, the insertion of SpaceOAR was significantly affected by chronological changes in PVR ( = 0.001). Three months after LDR-BT, PVR in the SpaceOAR group was significantly higher than that in the non-SpaceOAR group (49.8 mL vs. 30.5 mL;  = 0.002).

Conclusion: SpaceOAR use may temporally increase PVR; however, IPSS, OABSS, IPSS-QOL, Qmax, and voided volume were not significantly associated with LUTS before and after LDR-BT. The combination of LDR-BT and SpaceOAR may be acceptable for treating patients with prostate cancer regarding the chronological changes in LUTS after brachytherapy.