The effects of external beam radiotherapy on the normal urinary bladder - A histopathological review

Introduction: This literature review presents information relevant to medical radiation technologists with respect to new knowledge on the function of the urinary bladder. These new insights are also explored in relation to radiation-induced histopathological effects and the symptoms of bladder dysfunction reported after external beam radiotherapy. Methods and Materials: The peer-reviewed scientific literature was examined using various electronic medical search engines with appropriate keywords and MeSH headings. Inclusion criteria comprised English language articles published between 1999 and January 2010, with full manuscript available. A critical review was then performed, synthesizing the information contained in those multiple sources into the following subject categories: normal urinary bladder function (basic review and new knowledge), and effect of fractionated radiotherapy on normal bladder (histopathological changes and symptoms of dysfunction). Findings: Previously considered an inert vessel for urine storage, the urinary bladder is actually a complex system of morphologically different tissues, which play an interconnected role in its physiological functions. Injury or abnormal repair in any of the bladder cell layers results in a multifaceted display of interrelated manifestations of dysfunction. In this complex environment, not only can a single symptom of dysfunction have multiple histopathological causes, but the presence of one symptom may exacerbate the presentation of another. To date, this new knowledge has had little impact on radiotherapy clinical practice because subjective methods of collecting toxicity data prevent the identification of a link between radiotherapy dose and urinary dysfunction. The new understanding of the histopathological cause of radiation-induced symptoms, however, has led to the preclinical investigation of many promising methods to prevent or reduce radiotherapy toxicity.