Correlation Between Bladder Dosimetry and Patient-Reported Acute Urinary Quality of Life During Modern Post-prostatectomy Image-Guided IMRT

Abstract

Radical prostatectomy causes urinary symptoms including frequency and urgency, and post-prostatectomy (adjuvant or salvage) RT can further add to these symptoms during the RT treatment course. However, dosimetric correlations between bladder dose and acute urinary symptoms in the post-prostatectomy setting are understudied. The correlation between patient-reported urinary symptoms during RT and bladder dosimetry are the focus of this analysis. 90 consecutive patients treated from 2010-2015 with post-prostatectomy image-guided IMRT at a single institution were included. Patient-reported urinary symptoms using the validated Prostate Cancer Symptom Indices (PCSI) were collected pre-RT and weekly during treatment. PCSI assessed urinary frequency, urgency, flow, dysuria, incontinence, and nocturia graded on a Likert scale of 1 to 4 or 5. For this analysis, a ≥2 point increase in a symptom at any time during treatment compared to baseline was considered a clinically significant toxicity. Doses to the bladder and bladder wall were compared for patients who developed each urinary symptom vs those who did not. Receiver-operator curves were generated for each of those comparisons and the area under the curve (AUC) was used to assess the strength of the correlation. Patients were treated to a median dose of 66.6 Gy and 56% received concurrent ADT. Median time from surgery to RT was 1.6 years. Whole bladder doses (V10-V50) were correlated with worsening of urinary frequency, nocturia, incontinence, and urgency (Table) with AUC of 0.58-0.67. Higher bladder doses (≥V60) had a less strong association with AUC 0.55-0.67. There was no clear association between bladder dosimetry and urinary flow or dysuria. Results were similar with whole bladder and bladder wall dosimetry. In the setting of post-prostatectomy IMRT, low and medium doses to the bladder are correlated with acute worsening of urinary frequency, nocturia and urgency. These findings add to the understanding of bladder dose constraints and can help minimize acute urinary toxicity.Abstract 2619; TableWhole bladder dosimetry correlations with urinary symptomsSymptomVxAUCNo Toxicity (mean ± standard deviation)Toxicity (mean ± standard deviation)FrequencyV10 (cc)0.65106 ± 45144 ± 71V50 (cc)0.6266 ± 2677 ± 27NocturiaV10 (cc)0.64107 ± 50132 ± 56V50 (cc)0.6365 ± 2578 ± 32UrgencyV10 (%)0.6490 ± 1695 ± 13V50 (%)0.6556 ± 1968 ± 22IncontinenceV10 (%)0.5891 ± 1695 ± 9V50 (%)0.5959 ± 2165 ± 20 Open table in a new tab