3314 - Urinary Toxicity after External Beam Radiation Therapy for Prostate Cancer following Transurethral Resection of Prostate or Laser Enucleation
Presenter(s)
P. Patel1, S. J. Shah2, O. Mohamad2, H. Mok3, S. Choi4, K. E. Hoffman2, C. Tang3, L. L. Mayo2, R. J. H. Park5, S. E. McGuire3, Q. N. Nguyen6, S. J. Frank3, B. Chapin7, W. Graber1, and C. J. Hassanzadeh3; 1MD Anderson Cancer Center, Houston, TX, 2Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of Genitourinary Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 4Division of Radiation Oncology The University of Texas MD Anderson Cancer Center, Houston, TX, 5Harvard Radiation Oncology Program, Boston, MA, 6The University of Texas MD Anderson Cancer Center, Houston, TX, 7Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s): To study the impact of transurethral resection of prostate (TURP) or laser enucleation before external beam radiation therapy (EBRT) on development of late genitourinary toxicities
Materials/Methods: Patients diagnosed with prostate cancer who received TURP or laser enucleation prior to EBRT to the prostate +/- seminal vesicles and pelvic lymph nodes at a single institution were eligible for this study. Severity of acute (onset during therapy) and late (beyond 90 days of EBRT completion) GU/GI toxicities was graded per NCI CTCAE criteria.
Results: A total of 79 patients were included with a median follow-up of 34.3 months [IQR 16.8 – 74.2]. Median age was 75 years [IQR 70 – 78]. Median time from TURP or laser enucleation to EBRT was 3.9 months [IQR 2.8 – 5.7]. 3 patients underwent holmium/greenlight laser enucleation, and the remainder underwent TURP. 55 (70%) of patients received IMRT, 22 (28%) proton therapy, and 2 (3%) SBRT (conventional = 53; moderately hypofractionated = 24, SBRT = 2). 89% of patients received anti-androgen therapy (ADT). 49% of patients were on alpha-1 antagonists at presentation. Median baseline American Urological Association (AUA) Symptom Score was 20 [15.5-24], and median change from baseline pre-TURP to post-RT was 0 [IQR -3 – 3]. Incidence of late grade 1-3 urinary toxicity was 20%, with the most common being urinary frequency (50%, 8/16) and dysuria (25%, 4/16). Incidence of grade 2+ late urinary toxicity was 4% (3/79). 2 cases of grade 3 urinary toxicity were observed in patients who received conventional fractionation and consisted of cystitis and hematuria/dysuria. Younger age was associated with a lower risk of late grade 1-3 GU toxicity on logistic regression (HR 0.35; 95% CI 0.13-0.53, p=0.002); alpha-1 antagonist/diuretic use, ADT receipt, fraction size, and proton therapy were not significantly associated. Among those with any late grade 1-3 GU toxicity compared to those without, median age was 79.5 vs. 74 years and baseline AUA was 23 vs. 20 with median TURP to RT duration of 3.9 months across both groups.
Conclusion: In patients with prior TURP or laser enucleation treated with EBRT, incidence of severe late urinary toxicity is overall low. There were no detected cases of urinary obstruction. There was a significant association between age and the development of late urinary toxicity, while medical management of urinary symptoms, ADT receipt, fraction size, and proton therapy were not significantly associated. In conjunction with prior studies, these findings support that EBRT is well-tolerated after TURP or laser enucleation, including those who received non-conventional fractionation.