Radiation Therapy

External-beam radiation therapy, brachytherapy, or a combination is sometimes used as the primary therapy for early-stage proximal urethral cancers, particularly in women.[Level of evidence C3] Brachytherapy may be delivered with low-dose-rate iridium Ir 192 sources using a template or urethral catheter. Definitive radiation is also sometimes used for advanced-stage tumors, but because monotherapy of large tumors has shown poor tumor control, it is more frequently incorporated into combined modality therapy after surgery or with chemotherapy.[4] There are no head-to-head comparisons of these various approaches, and patient selection may explain differences in outcomes among the regimens.[Level of evidence C3]

The most commonly used tumor doses are in the range of 60 Gy to 70 Gy. Severe complication rates for definitive radiation therapy are about 16% to 20% and include fistula development, especially for large tumors invading the vagina, bladder, or rectum. Urethral strictures also occur in the setting of urethral-sparing treatment. Toxicity rates increase at doses greater than 65 Gy to 70 Gy. Intensity-modulated radiation therapy has become more common in an attempt to decrease local morbidity of the radiation.[4]