[en] A series of 245 patients with prostate cancer treated by external irradiation was analysed to assess the impact of irradiation on urinary outlet obstruction. Prior to irradiation obstruction was observed in 147/245 patients (60%). Irradiation either with or without hormonal therapy was as efficacious as transurethral resection of the prostate (TURP) in alleviating obstructive symptoms; 14/16 patients treated by irradiation alone responded, as did 19/19 who received hormonal therapy and irradiation and 109/112 who underwent TURP and irradiation. Following irradiation, 41/245 patients developed post-irradiation obstruction, 26/213 had post-irradiation strictures and 15/32 developed recurrent cancer. Surgical intervention was required less often for the management of recurrent obstruction caused by stricture as compared with recurrent cancer. TURP and urinary outlet obstruction acted as independent and additive variables to the development of post-irradiation stricture. Thus the avoidance of TURP in patients with obstructive symptoms reduced but did not eliminate the risk of developing a stricture. (Author)