Comparison of Late Urinary Symptoms Following SBRT and SBRT with IMRT Supplementation for Prostate Cancer

Abstract

Background: Prostate cancer survivors commonly experience late-onset lower urinary tract symptoms following radiotherapy. We aimed to compare lower urinary tract symptoms in patients treated with stereotactic body radiotherapy (SBRT) to those treated with a combination of lower dose SBRT and supplemental intensity-modulated radiotherapy (SBRT + IMRT). Methods: Subjects with localized prostate carcinoma scheduled to receive SBRT or a combination of SBRT and IMRT were enrolled and followed for up to 2 years after treatment completion. Participants treated with SBRT received 35-36.25 Gy in 5 fractions, while those treated with SBRT + IMRT received 19.5 Gy of SBRT in 3 fractions followed by 45-50.4 Gy of IMRT in 25-28 fractions. Urinary symptoms were measured using the American Urological Association (AUA) Symptom Score. Results: Two hundred patients received SBRT (52% intermediate risk, 37.5% low risk according to D'Amico classification) and 145 patients received SBRT + IMRT (61.4% high risk, 35.2% intermediate risk). Both groups experienced a transient spike in urinary symptoms 1 month after treatment. More severe late urinary flare (increase in AUA scores ≥ 5 points from baseline to 1 year after treatment completion and an AUA score ≥ 15 at 1 year after treatment) was experienced by patients who received SBRT compared to those treated with SBRT + IMRT. Conclusion: Participants who received SBRT and supplemental IMRT experienced less severe late urinary flare 1 year after treatment compared to those who received higher dose SBRT alone. This information can be used by clinicians to provide patients with anticipatory counseling to mitigate any psychological burden that comes with unanticipated late urinary toxicities.

Phase I/II Study of Extreme Hypofractionated Stereotactic Body Radiation Therapy Boost to Prostate for Locally Advanced, Node-Positive and Oligometastatic Cancer

“…Efficient RT planning, use of dedicated rectal emptying and bladder filling protocols, omission of uninvolved portion of the seminal vesicles from the target volume, limiting of posterior PTV margins to limit the rectal volume being irradiated, delineation of urethra and limiting hot-spots inside it, daily image-guidance for VMAT, intrafraction motion tracking on CK by use of implanted fiducials, alternate-day treatment schedule for CK-SBRT, and delivering CK-SBRT before VMAT are some of the factors responsible for limiting late toxicity. A study by Feng et al [ 24 ] compared late GU toxicity between two schedules of SBRT alone versus a combination of IMRT and SBRT boost similar to our study and found lesser toxicity with the latter approach. Patients with prostate volume >50cc at baseline have been shown to experience greater GU toxicity [ 25 ].…”

Safety and Efficacy of Virtual Prostatectomy With Single-Dose Radiotherapy in Patients With Intermediate-Risk Prostate Cancer

“…Urethra sparing with the same dose reductions was also used in both study arms. Nonetheless, there was a trend toward higher patient-reported mild GU discomfort with SDRT, and, consistently, the incidence of a transient late urinary flare syndrome was higher following SDRT. The cause of this self-limiting phenomenon probably resides in the dose to the bladder trigone, rather than in the urethra, and the implementation of stricter SDRT dose/volume constraints in this area is therefore warranted, as it may abrogate this late adverse effect .…”

Virtual HDR Boost for Prostate Cancer: Rebooting a Classic Treatment Using Modern Tech

“…Even though the cumulative incidence was high in this trial over time, most of the subacute toxicity resolved by the 2 year mark. Interestingly, this 12 month GU flare toxicity seemed to be lower in vHDRB compared to SBRT monotherapy (7.60 ± 0.42 and 9.53 ± 0.47, p = 0.003), as reported by Feng using the American Urological Association (AUA) symptom index [ 48 ]. Katz and Kang [ 31 ] may also support this, with lower late GU G3 toxicity seen in the vHDRB group compared to the SBRT monotherapy arm (2.3% versus 3.9%) and 2.3% versus 7.8% for late GU G2 toxicity.…”