Urinary Obstruction in Prostate Cancer Patients From the Dutch Trial (68 Gy vs. 78 Gy): Relationships With Local Dose, Acute Effects, and Baseline Characteristics

(a, b) Coronal and sagittal views of computed tomography scan in prostate/bladder region for template patient (blue, bladder; black, prostate; dark red, rectum). Cross indicates trigone point 2 cm above starting point of prostatic urethra in coronal slice with urethra visible. Asterisk in Fig. b indicates region in which largest dose differences were found (see Fig. 1e, f). (c, d) Average planned dose for all patients in corresponding coronal and sagittal views. Apart from delineated organs, contours of standard deviations included to indicate roughly area of largest dose variations (green, 10-Gy contour; orange, 15 Gy; yellow, 20 Gy). (e, f) Dose difference maps (coronal and sagittal views). Mean dose map of patients without urinary obstruction subtracted from mean dose map of patients with obstruction. White region indicates significant (p < .02) dose differences (range 4–12 Gy). Asterisk in Fig. f indicates region with largest dose differences.

Kaplan-Meier curve showing greater incidence (p = .001) of late urinary obstruction for patients with previous transurethral resection of prostate compared with those without previous transurethral resection of prostate.

Absolute dose–surface histograms for patients with and without urinary obstruction.

Kaplan-Meier estimates for obstruction. (a) Cumulative incidence for subgroups receiving dose greater than and less than mean dose to trigone point. (b) Cumulative incidence for patients with and without hotspots (surface <0.5 or >0.5 cm² received >80 Gy) for subgroup receiving radiation dose >76 Gy (total n = 256, n = 39 with surface >0.5 cm²).