Natural history of lower urinary tract symptoms among men undergoing stereotactic body radiation therapy for prostate cancer with and without a Rectal Hydrogel Spacer

One-year clinical outcomes of MR-guided stereotactic body radiation therapy with rectal spacer for patients with localized prostate cancer

BACKGROUND AND PURPOSE

This prospective study aimed to investigate adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (MRgSBRT) with rectal spacer for localized prostate cancer (PC) and report 1-year clinical outcomes.

MATERIALS AND METHODS

Thirty-four consecutive patients with low- to high-risk localized PC that underwent 5-fraction adaptive MRgSBRT with rectal spacer were enrolled. The dosimetric comparison was performed on a risk- and age-matched cohort treated with MRgSBRT but without a spacer at a similar timepoint. Clinician-reported outcomes were based on Common Terminology Criteria for Adverse Events. Patient-reported outcomes were based on the Expanded Prostate Cancer Index Composite (EPIC) questionnaire at baseline, acute (1-3 months), subacute (4-12 months), and late (> 12 months) phases.

RESULTS

The median follow-up was 390 days (range 28-823) and the median age was 70 years (range 58-82). One patient experienced rectal bleeding soon after spacer insertion that subsided before MRgSBRT. The median distance between the midline of the prostate midgland and the rectum after spacer insertion measured 7.8 mm (range 2.6-15.3), and the median length of the spacer was 45.9 mm (range 16.8-62.9) based on T2-weighted MR imaging. The use of spacer resulted in significant improvements in target coverage (V100% > 95% = 98.6% [range 93.4-99.8] for spacer vs. 97.8% [range 69.6-99.7] for non-spacer) and rectal sparing (V95% < 3 cc = 0.7 cc [range 0-4.6] for spacer vs. 4.9 cc [range 0-12.5] for non-spacer). Nine patients (26.5%) experienced grade 1 gastrointestinal toxicities, and no grade ≥ 2 toxicities were observed. During the 1-year follow-up period, EPIC scores for the bowel domain remained stable and were the highest among all other domains.

CONCLUSIONS

MRgSBRT with rectal spacer for localized PC showed exceptional tolerability with minimal gastrointestinal toxicities and satisfactory patient-reported outcomes. Improvements in dosimetry, rectal sparing, and target coverage were achieved with a rectal spacer. Randomized trials are warranted for further validation.

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 (P = 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; P = 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.