TY - JOUR
T1 - Predictors of urinary toxicity with MRI-assisted radiosurgery for low-dose-rate prostate brachytherapy
AU - Boyce-Fappiano, David
AU - Bathala, Tharakeswara K.
AU - Ye, Rong
AU - Pasalic, Dario
AU - Gjyshi, Olsi
AU - Pezzi, Todd A.
AU - Noticewala, Sonal S.
AU - McGinnis, Gwendolyn J.
AU - Maroongroge, Sean
AU - Kuban, Deborah A.
AU - Nguyen, Quynh Nhu
AU - McGuire, Sean E.
AU - Hoffman, Karen E.
AU - Choi, Seungtaek
AU - Tang, Chad
AU - Kudchadker, Rajat J.
AU - Frank, Steven J.
N1 - Publisher Copyright:
© 2020 American Brachytherapy Society
PY - 2020/9/1
Y1 - 2020/9/1
N2 - Purpose: MRI-assisted radiosurgery (MARS) is a modern technique for prostate brachytherapy that provides superior soft tissue contrast. The purpose of this analysis was to evaluate treatment planning factors associated with urinary toxicity, particularly damage to the membranous urethra (MUL) and external urethral sphincter (EUS), after MARS. Material and Methods: We retrospectively reviewed 227 patients treated with MARS. Comparisons were made between several factors including preimplantation length of the MUL and EUS dosimetric characteristics after implantation with longitudinal changes in American Urological Association (AUA) urinary symptom score. Results: Rates of grade 3 urinary incontinence and obstructive urinary symptoms were 4% and 2%. A piecewise mixed univariate model revealed that MUL and V200, V150, V125, and D5 to the EUS were all associated with increased rates of urinary toxicity over time. On univariate logistic regression, MUL >14.2 mm (odds ratio [OR] 2.03 per cm3, 95% confidence interval [CI] 1.10–3.77, p = 0.025), V125 to the EUS (OR 3.21 cm3, 95% CI 1.18–8.71, p = 0.022), and use of the I-125 isotope (OR 3.45, 95% CI 1.55–7.70, p = 0.001) were associated with subacute urinary toxicity (i.e., that occurring at 4–8 months). Optimal dose-constraint limits to the EUS were determined to be V200 < 0.04 cm3 (p = 0.002), V150 < 0.12 cm3 (p = 0.041), V125 < 0.45 cm3 (p = 0.033), D30 < 160 Gy (p = 0.004), and D5 < 218 Gy (p = 0.016). Conclusions: MARS brachytherapy provides detailed anatomic information for treatment planning, implantation, and quality assurance. Overall rates of urinary toxicity are low; however, several dosimetric variables associated with the EUS were found to correlate with urinary toxicity.
AB - Purpose: MRI-assisted radiosurgery (MARS) is a modern technique for prostate brachytherapy that provides superior soft tissue contrast. The purpose of this analysis was to evaluate treatment planning factors associated with urinary toxicity, particularly damage to the membranous urethra (MUL) and external urethral sphincter (EUS), after MARS. Material and Methods: We retrospectively reviewed 227 patients treated with MARS. Comparisons were made between several factors including preimplantation length of the MUL and EUS dosimetric characteristics after implantation with longitudinal changes in American Urological Association (AUA) urinary symptom score. Results: Rates of grade 3 urinary incontinence and obstructive urinary symptoms were 4% and 2%. A piecewise mixed univariate model revealed that MUL and V200, V150, V125, and D5 to the EUS were all associated with increased rates of urinary toxicity over time. On univariate logistic regression, MUL >14.2 mm (odds ratio [OR] 2.03 per cm3, 95% confidence interval [CI] 1.10–3.77, p = 0.025), V125 to the EUS (OR 3.21 cm3, 95% CI 1.18–8.71, p = 0.022), and use of the I-125 isotope (OR 3.45, 95% CI 1.55–7.70, p = 0.001) were associated with subacute urinary toxicity (i.e., that occurring at 4–8 months). Optimal dose-constraint limits to the EUS were determined to be V200 < 0.04 cm3 (p = 0.002), V150 < 0.12 cm3 (p = 0.041), V125 < 0.45 cm3 (p = 0.033), D30 < 160 Gy (p = 0.004), and D5 < 218 Gy (p = 0.016). Conclusions: MARS brachytherapy provides detailed anatomic information for treatment planning, implantation, and quality assurance. Overall rates of urinary toxicity are low; however, several dosimetric variables associated with the EUS were found to correlate with urinary toxicity.
KW - Brachytherapy
KW - LDR
KW - MARS
KW - MRI guided
KW - Prostate cancer
UR - http://www.scopus.com/inward/record.url?scp=85087937224&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85087937224&partnerID=8YFLogxK
U2 - 10.1016/j.brachy.2020.06.011
DO - 10.1016/j.brachy.2020.06.011
M3 - Article
C2 - 32682778
AN - SCOPUS:85087937224
SN - 1538-4721
VL - 19
SP - 574
EP - 583
JO - Brachytherapy
JF - Brachytherapy
IS - 5
ER -