Anatomical Importance of the Bladder and Strategies to Minimize Toxicity in Pelvic Radiotherapy for Prostate Cancer: A Narrative Review

Abstract

Pelvic radiotherapy is a widely used curative treatment for prostate cancer. Due to its close anatomical proximity to the prostate, the bladder is highly susceptible to radiation-induced toxicity. Its variable volume and shape significantly influence dose distribution and the position of adjacent organs including the small bowel, making it a critical organ at risk during treatment planning. This review highlights the anatomical features and physiological functions of the bladder relevant to radiotherapy, the mechanisms of radiation-induced bladder injuries, and current strategies to minimize toxicity. Strategies to reduce bladder toxicity include consistent bladder filling or emptying protocols, with clinical studies supporting the feasibility of both. Empty bladder protocols have shown non-inferior outcomes in selected patients, improving setup reproducibility and patient compliance. Meanwhile, bladder filling helps reduce the dose to the bladder wall and displace small bowel from high-dose area. Bladder volume monitoring using cone-beam computed tomography (CBCT) or ultrasonography (US) allows for daily assessment of volume consistency. In particular, US offers a non-invasive, rapid alternative that correlates well with CBCT measurements. In summary, the bladder’s anatomical and functional variability presents both challenges and opportunities in prostate cancer radiotherapy. Integration of individualized preparation protocols and real-time imaging strategies is essential to reduce toxicity, enhance treatment accuracy, and improve patient outcomes.