Urethral cancer medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Role of Radiation Therapy
Radiation therapy with external beam, brachytherapy, or a combination is sometimes used for the primary therapy of early-stage proximal urethral cancers, particularly in women. Brachytherapy may be delivered with low-dose-rate iridium-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. There are no head-to-head comparisons of these various approaches, and patient selection may explain differences in outcomes among the regimens.
The most commonly used tumor doses are in the range of 60 Gy to 70 Gy. Severe complication rates for definitive radiation 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 come into more common use in an attempt to decrease local morbidity of the radiation.
Role of Chemotherapy
The literature on chemotherapy for urethral carcinoma is anecdotal in nature and restricted to retrospective, single-center case series or case reports. A wide variety of agents used alone or in combination have been reported over the years, and their use has largely been extrapolated from experience with other urinary tract tumors.
For squamous cell cancers, agents that have been used in penile cancer or anal carcinoma include:
- Cisplatin
- 5-Fluorouracil
- Bleomycin
- Methotrexate
- Irinotecan
- Gemcitabine
- Paclitaxel
- Docetaxel
- Mitomycin-C
Chemotherapy for transitional cell urethral tumors is extrapolated from experience with transitional cell bladder tumors and, therefore, usually contains the following:
- Methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC).
- Paclitaxel.
- Carboplatin.
- Ifosfamide, with occasional complete responses.
Chemotherapy has been used alone for metastatic disease or in combination with radiation therapy and/or surgery for locally advanced urethral cancer. It may be used in the neoadjuvant setting with radiation therapy in an attempt to increase the resectability rate or in an attempt at organ preservation.[3] However, the impact of any of these regimens on survival is not known for any stage or setting.