Erectile Function After 60 GY in 20 Fractions External Beam Radiotherapy to the Prostate
Recommended Citation
Bayley C, Quirk S, Braun J, Sun L, Smith W, Quon H, Thind K, Martell K. Erectile Function After 60 GY in 20 Fractions External Beam Radiotherapy to the Prostate. Radiother Oncol 2022; 174:S33.
Document Type
Conference Proceeding
Publication Date
9-1-2022
Publication Title
Radiother Oncol
Abstract
Purpose: To determine which factors predict for worsening erectile function after highly conformal, modestly hypofractionated radiotherapy to the prostate. Materials and Methods: All patients who received 60Gy in 20 fractions, volumetric modulated arc therapy to the prostate across four centres were included in this study. The provincial electronic medical record was interrogated to identify any new prescriptions for erectile dysfunction (ED) medication, any change in prescription of ED medication or any permanent discontinuance of ED medication persisting beyond six months post completion of any androgen deprivation therapy. The penile bulb, penile crux and glans penis structures were retrospectively contoured. A Youden receiver-operator-curve analysis and logistic regression were then used to determine dependencies between worsening ED and clinical factors including mean doses to these structures. Results: Two-hundred-twelve patients with median (inter-quartilerange) follow-up of 3.6 (3.2-4.4) years were identified. Median age was 72 (67-76) years. 104 (49%) patients received androgen deprivation therapy. Prior to treatment, 52 (25%) patients were on ED medication: 20 (9%) on sildenafil, 28 (13%) on tadalafil and 4 (8%) on vardenafil. Median PTV volume was 158.9 (129.8-192.1) cc. Median penile bulb, penile crux and glans penis volumes were 4.7 (3.6-6.2)cc, 6.5 (5.1-8.5)cc and 93.3 (80.6-106.2)cc, respectively. PTV V95 was 99.8 (99.5-99.9)%. Mean doses to penile bulb, penile crux and glans penis were 2094.8 (1306.2-3036.3)cGy, 2094.8 (1306.2-3036.3)cGy and 444.4 (313.2-650.5), respectively. Fifty-nine (28%) patients had a worsening of ED after treatment: 25 (12%) started a new ED medication, 6 (3%) had a prescription change and 28 (13%) stopped ED medication. On univariate analyses pretreatment use of ED medication predicted for worsening ED: OR yes versus no: 10.2 (5.0 – 20.8; p<0.001). A trend towards mean dose to penile bulb [OR ≤2343.9 versus >2343.9: 1.7 (0.9-3.2; p=0.08)] predicting for worsening ED was observed. Mean doses to penile crux [OR <1725.8 versus > 1725.8: 2.6 (1.3-5.2; p=0.005)] and glans penis [OR ≤344.9 versus >344.9: 5.2 (2.2-12.2; p<0.001)] predicted for worsening ED. Use of androgen deprivation therapy, and age at time of radiotherapy were not predictive of worsening ED. On multivariate analysis, only mean dose to glans penis [OR ≤344.9 versus >344.9: 6.3 (1.9-20.3; p=0.002)] and pretreatment use of ED medication [OR yes versus no: 11.1 (5.3-23.2; p<0.001)] predicted for worsening ED. Conclusions: In this limited analysis, pre-treatment use of ED medication and mean dose to glans penis predicted for worsening ED after treatment with modestly hypofractionated radiotherapy for prostate cancer
Volume
174
First Page
S33
