Purpose: A pilot study was performed to determine the effectiveness of Flomax (tamsulosin HCl) in the management of acute radiation urethritis in prostate cancer patients undergoing conformal external beam radiation therapy (RT). Potential predictors of response to Flomax were evaluated.
Methods and materials: From January 1998 to April 1998, 26 consecutive patients who developed symptoms of radiation urethritis while undergoing RT for prostate cancer were treated with Flomax, a superselective alpha1A-adrenergic antagonist. A genitourinary review of systems served as the instrument used to assess baseline urinary function and treatment response.
Results: The initial response rate to Flomax was 62% (16/26) at the 0.4 mg level and 60% (6/10) at the 0.8 mg level. Half of the 16 patients who initially responded to 0.4 mg subsequently progressed. Three-fourths of those patients who progressed, however, achieved a durable response with the 0.8 mg dose. Therefore urinary symptoms were ultimately controlled in 77% (20/26) of the patients. After correcting for the testing of multiple hypotheses (n = 5), the presence of benign prostatic hyperplasia (BPH) approached statistical significance for predicting the initial response to the 0.4 mg dose of Flomax (78% vs. 25%, p = 0.03).
Conclusion: Flomax appears to be effective in relieving the symptoms of radiation urethritis. A Phase II trial is justified and in progress.