The clinical manifestation of radiation to the lower urinary tract can be categorized into acute and late reactions. Acute reactions occur during and up to 3 months after radiation exposure. Most acute symptoms subside within several weeks of standard radiation therapy. Late reactions occur at least 3 months after radiation exposure.

Acute radiation-induced symptoms can be irritative or obstructive, and depend on gender, region of exposure, and dose. Radiation-induced inflammation, edema, and loss of urothelial integrity are thought to be the underlying events that contribute to acute symptoms. Irritative symptoms include increased urinary frequency, dysuria, urgency, and nocturia. Obstructive symptoms include weak stream, incomplete voiding, hesitancy, and in rare cases, complete obstruction with overflow incontinence. It is difficult to distinguish between the side effects of radiation to the prostate and radiation to the bladder, as both can manifest similarly. The reported incidence of acute toxicity varies from 23% to 80% in patients treated with radiation to the pelvis for various malignancies.32,33,34,35,36,37,38–39 Such wide range in incidence rates reflects the heterogeneity in treatment techniques, dose, and treatment fields for different malignancies and also reflects the inherent difficulty in collecting such subjective data.

The Radiation Therapy Oncology Group (RTOG) has published scoring criteria for a qualitative assessment of the degree of acute radiation morbidity40 (Table 32.1). Acute toxicity is scored from days 1 through 90. Symptoms related to radiation exposure must be distinguished ...