[Normal tissue tolerance to external beam radiation therapy: bladder]

Abstract

The bladder is a hollow visco-elastic organ involved in urinary continence. In relation to its anatomical location, bladder is exposed in whole or in part to ionizing radiation in external radiotherapy or in brachytherapy of the pelvic region. The acute and late functional changes after external beam radiation consist in urinary frequency, compliance defaults and hematuria. Incidence of urinary side-effects, as well as related modalities of radiotherapy, is poorly described in the literature. Medline literature searches were performed via PubMed using the keywords "bladder--radiotherapy--toxicity--radiation cystitis--tolerability--organ at risk" to describe urinary side-effects due to radiation. Some recommendations exist on the dose constraints applied to bladder. These were mainly established from prostate radiation therapy studies but without definitive consensus. In clinical practice, dose constraints take into account clinical settings: bladder cancer which requires total bladder irradiation or others pelvic tumours (prostate, uterus...) in which the bladder is considered as an organ at risk. Risks of radiation cystitis increase with total dose (above 60 Gy), bladder irradiated volume and concomitant chemoradiation. Modern techniques using conformal radiotherapy with modulated intensity will probably have beneficial impact on bladder toxicity.