Is there a relation between the radiation dose to the different sub-segments of the lower urinary tract and urinary morbidity after brachytherapy of the prostate with I-125 seeds?

Dose to the Bladder Neck Is the Most Important Predictor for Acute and Late Toxicity After Low-Dose-Rate Prostate Brachytherapy: Implications for Establishing New Dose Constraints for Treatment Planning

“…Higher urethral dose at the prostate base, larger prostate volume, and larger number of needles were associated with a higher maximum IPSS during the first year after the implant, suggesting the importance of outlining the urethral base [14]. Steggerda et al [13] proposed bladder neck D0.5cc >175 Gy (120.7%) of the prescription dose as a potential dose constraint for patients treated with I-125 definitive brachytherapy. The authors did not specify the mean bladder neck volume contoured.…”

“…Retrospective reports have drawn associations between various factors such as urethral dose, prostate volume, baseline International Prostate Symptom Scores (IPSS), use of neoadjuvant androgen-deprivation therapy (ADT), and greater number of needles implanted with increased risk of significant acute urinary toxicity [11]. Several small retrospective reports have investigated the correlation of urinary toxicity with the dose to the lower urinary tract segments [12] and found an association between the dose to the urethral base/bladder neck and urinary toxicity [13, 14]. We previously reported a strong association between the dose to the bladder neck/trigone and long-term urinary function in patients treated with EBRT for prostate cancer [15].…”

Histopathology-derived modeling of prostate cancer tumor control probability: Implications for the dose to the tumor and the gland

“…Given this limitation, the benefit of dose differentiation needs to be established in clinical trials. The dose to the bladder neck is an important parameter for the genitourinary toxicity [25]. Dose reduction by 7-10 Gy in the CTV may reduce this toxicity, as most tumors do not present anteriorly in the gland.…”

DNA repair gene polymorphisms, tumor control, and treatment toxicity in prostate cancer patients treated with permanent implant prostate brachytherapy

“…The regression models included pretreatment IPSS, age, hormone‐therapy status, Gleason score, PSA level, prostate volume, and htSNP as potential predictors of posttreatment IPSS. Because the vast majority of our patients were treated before 2014, when evidence found that dose delivered to the bladder neck was associated to urinary toxicity, 18‐20 this dosimetry parameter could not be included in our toxicity analysis. The posttreatment IPSS values were compared for every level of significant htSNP at a constant IPSS pretreatment value by analysis of covariance (ANCOVA).…”