Changes in Bladder Volume During Radiotherapy for Prostate Cancer.

Background/aim: Patients irradiated for prostate cancer may experience urinary toxicity, particularly if the bladder volume is small. A mobile application (app) that reminds the patients to drink water prior to each radiation fraction may help avoid small volumes. This study investigating bladder volumes during a radiotherapy course is a prerequisite for a prospective trial testing such a reminder app.

Patients and methods: Frequency of bladder volumes <200 ml and seven potential risk factors were retrospectively evaluated in 72 patients receiving external beam radiotherapy for non-metastatic prostate cancer.

Results: The mean and median values of the numbers of radiation fractions with bladder volumes <200 ml were 17.8 (standard deviation=12.0) and 16.5 (interquartile range Q1-Q3=7.5-29.5) fractions, respectively. Higher numbers of fractions with volumes <200 ml were significantly associated with pre-radiotherapy bladder volumes <200 ml (p<0.001) and high-risk prostate cancer (p=0.014).

Conclusion: The proportion of bladder volumes <200 ml during the radiotherapy course was high and needs to be decreased. Pre-radiotherapy bladder volume and risk level of prostate cancer were significant risk factors for higher numbers of fractions with volumes <200 ml. These results are important for designing a prospective trial.