Changes in lower urinary tract symptoms after prostate brachytherapy with the use of SpaceOAR® system

Iinuma K1, Mizutani K1, Taniguchi T1, Kato T2, Nakano M3, Kato D1, Takai M1, Maekawa Y1, Nakane K1, Tsuchiya T1, Tsuboi Y4, Ishihara T4, Ito M5, Kumano T5, Matsuo M5, Koie T1

Research Type

Clinical

Abstract Category

Male Lower Urinary Tract Symptoms (LUTS) / Voiding Dysfunction

Abstract 131
Incontinence from Prostate Cancer Treatment
Scientific Podium Short Oral Session 9
On-Demand
Male Quality of Life (QoL) Voiding Dysfunction
1. Department of Urology, Graduate School of Medicine, Gifu University, 2. Department of Urology, Asahi University Hospital, 3. Department of Urology, Gifu Prefectural General Medical Center, 4. Gifu University Hospital Innovative and Clinical Research Promotion Center, 5. Department of Radiology, Graduate School of Medicine, Gifu University
Presenter
K

Koji Iinuma

Links

Abstract

Hypothesis / aims of study
Permanent iodine-125 low-dose-rate brachytherapy (LDR-BT) with or without external beam radiotherapy (EBRT) has been one of the standard definitive radiotherapies for localized prostate cancer. As the LDR-BT has been refined, delivered radiation doses have increased, thus maximizing the therapeutic potential of LDR-BT. However, the escalation of local radiation doses may result in acute or chronic toxicities, including genitourinary (GU) or gastrointestinal (GI) toxicities. The SpaceOAR® System (SpaceOAR) (Augmenix Inc., Waltham, MA, USA) is a synthetic polyethylene glycol hydrogel injected between the prostate and rectum that moves the rectum away from the prostate to reduce irradiation of the anterior rectal wall. It has been reported that SpaceOAR led to a reduction in GI events by reducing rectal exposure, furthermore it reduced the GU toxicity and urethral dose of prostate cancer patients treated with EBRT. However, there were few studies which evaluate changes in lower urinary tract symptoms (LUTS) of prostate cancer patients who underwent radiation therapy in combination use of SpaceOAR. We therefore investigated changes of LUTS in patients who were treated with LDR-BT with the use of SpaceOAR.
Study design, materials and methods
This study was approved by the institutional review board. From August 2004 to February 2020, 483 patients underwent LDR-BT for localized prostate cancer at our hospital. Of those, 30 patients were treated with LDR-BT in combination use of SpaceOAR (SpaceOAR group), and 453 patients were treated with LDR-BT alone (non-SpaceOAR group).
All LDR-BT with iodine-125 seeds were performed using the ultrasonography-guided intraoperative transperineal technique. The prescribed minimum peripheral doses of iodine-125 seeds were 145Gy for LDR-BT alone and 104Gy for LDR-BT + EBRT. To minimize the artifact in ultrasound imaging and avoidance of potential pubic arch interference SpaceOAR placement was carried out just after seed implantation. Neoadjuvant androgen deprivation therapy (ADT) was used for reducing prostate volume and/or for anticancer effects as required. Alpha-1 blocker was routinely initiated on all patients after LDR-BT to reduce risk of urinary retention, and it was discontinued after recovery of LUTS.
LDR-BT post plan CT and MRI were taken 30 day after seed implantation, and dosimetric parameters (minimum dose received by 90% of the target volume [D90], percentage of target volume receiving minimum of 100% of prescribed dose [V100], minimum dose received 30% of urethral volume [UD30], rectal volume receiving minimum of 100% of prescribed dose [RV100], rectal volume receiving minimum of 150% of prescribed dose [RV150]) were evaluated. To evaluate LUTS, the changes from pretreatment in International Prostate Symptoms Score (IPSS), Overactive Bladder Symptoms Score (OABSS) and quality of life due to urinary symptoms (IPSS-QOL) were assessed at 1, 3, 6, 9, 12 months after LDR-BT. Uroflowmetry and post-voided residual urine (PVR) were also assessed at pretreatment, 1, 3, 6, 9 and12 months. 
Linear mixed-effect models were used to analyze the longitudinal data and to assess the least square means differences between two groups at the period of each measurement. The interaction term between SpaceOAR group and period were incorporated into the model to evaluate the effect mofdification. In addition, age, body mass index (BMI), ADT, number of seeds, prostate volume, D’Amico risk classification and baseline value of outcome were treated as adjusted variables in each model. All analyses used 5% two-sided significant level and performed using R software version 3.6.3 (www.r-project.org) with “lme4” package.
Results
The patient characteristics are shown in Table. The median age at baseline, median prostate-specific-antigen (PSA) at diagnosis of prostate cancer, and median prostate volume at LDR-BT were 66 years (interquartile range [IQR]; 62-71 years), 6.4 ng/mL (IQR; 5.1-9.0 ng/ mL) and 22.5 mL (range; 17.7-29.1 mL), respectively in non-SpaceOAR group and 72 years (IQR; 61.3-71 years), 7.3 ng/ mL (IQR; 5.8-10.6 ng/ mL) and 27.3 mL (range; 21.4-31.8 mL), respectively in SpaceOAR group. The LDR-BT + EBRT consisted of 192 patients (42.4%) in non-SpaceOAR group and 16 patients (53.3%) in SpaceOAR group. The median IPSS, OABSS, IPSS-QOL, maximum flow rate (Qmax), voided volume (VV), and PVR before LDR-BT were 5 (IQR; 3-9), 3 (IQR; 2-4), 2 (IQR; 1-3), 17.6 mL/s (IQR; 14.5-21.7 mL/s), 250 mL (IQR; 183-349 mL) and 15.0 mL (IQR; 3.9-30 mL), respectively in non-SpaceOAR group and 7 (IQR; 3-10), 3 (IQR; 2-5), 3 (IQR; 1-4), 15.1 mL/s (IQR; 11.7-19.1 mL/s), 177.8 mL (IQR; 125.8-292.5 mL) and 30 mL (IQR; 2.0-52.5 mL), respectively in SpaceOAR group. There were no significant differences of D90, V100, and UD30 between two groups, while RV100 (p<0.001) and RV150 (p=0.033) were significantly lower in SpaceOAR group.
Both in non-SpaceOAR group and SpaceOAR group, IPSS, OABSS, and IPSS-QOL increased at 3 months after LDR-BT, and the scores decreased at 12 months. Analysis of variance revealed that follow-up time was significantly related change of IPSS, OABSS, and IPSS-QOL (p<0.001, p<0.001 and p<0.001, respectively). SpaceOAR did not show significant differences in relationship between follow-up time and following factors, IPSS, OABSS and IPSS-QOL. Although transient deterioration of Qmax and VV were observed, all factors recovered in 6 to 9 months after LDR-BT in both group. Analysis of variance revealed that follow-up time was significantly related changes of PVR (p<0.001). Interestingly, the use of SpaceOAR significantly affected chronological change in PVR (p=0.001). The least square mean of PVR in SpaceOAR group was significantly increased compared with non-SpaceOAR group at 3 months after LDR-BT (49.8mL vs 30.5mL, p=0.002).
Interpretation of results
SpaceOAR significantly reduce irradiation of the rectum, which is same as previous reports. Although post-voided volume increased significantly in SpaceOAR group at 3 months after LDR-BT, changes in following factors IPSS, OABSS, IPSS-QOL and uroflowmetry were not significant. Less than 50 mL of PVR that could not affect symptoms may explain this discrepancy.
Concluding message
This is the first study demonstrating changes in LUTS in prostate cancer patients who were treated with LDR-BT in combination use of SpaceOAR. The use of SpaceOAR may increase PVR temporally along with no significant change in LUTS after treatment of LDR-BT. Overall, changes in LUTS after LDR-BT in combination use of SpaceOAR were seemed to be tolerable.
Figure 1 Table
Disclosures
Funding None. Clinical Trial No Subjects Human Ethics Committee Gifu university Helsinki Yes Informed Consent Yes
27/03/2024 17:15:11