Bladder filling during radiation therapy for prostate cancer treatment: Assessment via bladder ultrasound scanner.

Abstract

147 Background: Prostate cancer patients treated with external beam radiation therapy are instructed to present daily with a full bladder to decrease small bowel and bladder toxicity and to increase reproducibility of treatment. However, older patients may have difficulty presenting with full bladders and variation of bladder volume with treatment is unknown. The objective of this study was to assess bladder filling at the time of radiation treatment (RT) using a bladder ultrasound in patients undergoing treatment for prostate cancer. Methods: Patients with prostate cancer were prospectively enrolled prior to CT simulation from January to August 2017. Bladder volume was recorded during CT simulation and daily immediately prior to RT. Patients were instructed to drink 8-12 ounces of water 30-60 minutes prior to RT. Three bladder volume measurements were recorded daily and averaged at the time of each treatment. Average bladder volume during treatment and the number of treatments with low bladder volumes ( < 50cc, < 60cc, and < 100cc) were reported using descriptive statistics. Results: A total of 13 patients completed a median of 42 days of RT during the study period, resulting in 550 daily bladder volumes. Ten patients were treated definitively and 3 with salvage radiation after prostatectomy. The median age of patients in the study was 72 years. Older patients were statistically more likely to present with low bladder volumes, with percentage of treatments with a bladder volume less than 50cc, 60cc, and 100cc being 29%, 42%, and 66% compared to only 4%, 7%, and 18% in patients aged < 70 (P < 0.01). The average bladder volume at the time of CT simulation was 176cc ± 57cc and the average volume during treatment was 140cc± 93cc, which was not statistically different (P = 0.28). The bladder volume did not significantly change over the course of treatment. Conclusions: Older patients (age 70+) with prostate cancer were more likely to present for RT with low bladder volumes in this prospective study. Our findings suggest that older patients should receive extra counseling about bladder filling and/or may require less bladder filling at the time of CT simulation to provide more accurate bowel dosimetry measurements.

Prostate Cancer Volumetric Arc Therapy (VMAT) Analysis

“…The large standard deviation (±113.44 cc) seen in bladder volume in our study, suggests a higher degree of variability for bladder filling. Waddle et al [18] analyzed data from several patients and indicated the age to be a potential factor. It was also revealed that more than 30% of patients with high-risk prostate cancer have prior bladder issues which makes the underlying toxicity difficult to assess [19].…”

The feasibility of a dose painting procedure to treat prostate cancer based on mpMR images and hierarchical clustering

“…It is obvious that if possible, the patients should ideally maintain a full bladder, but the bladder volume in patients with prostate cancer is reported to be unknown. Bladder volume reproducibility is typically enhanced through water consumption, but the optimal amount of water to be consumed remains unclear [ 31 , 32 ]. When the rectal filling differed considerably on the patients' CT-scan and mpMR images, new scans were performed to minimize the fusion uncertainty between the imaging modalities.…”

Bladder volume reproducibility after water consumption in patients with prostate cancer undergoing radiotherapy: A systematic review and meta-analysis

“…Patients should ideally maintain a full bladder if possible, but the bladder volume in patients with prostate cancer was reported to be unknown [ 12 , 13 ]. However, an increased bladder volume in the high-dose region loops resulted from treatment plans which were conducted with an empty bladder [ 5 , 6 ].…”