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Long Term Results of a Phase III Randomized Prospective Trial of Erectile Tissue Sparing IMRT for Men with Clinically Localized Prostate Cancer. International journal of radiation oncology, biology, physics Zhang, E., Ruth, K. J., Buyyounouski, M. K., Price, R. A., Uzzo, R. G., Sobczak, M. L., Pollack, A., Wong, J. K., Chen, D. Y., Hallman, M. A., Greenberg, R. E., Watkins-Bruner, D., Al-Saleem, T., Horwitz, E. M. 2022

Abstract

To determine if limiting the doses delivered to the penile bulb (PB) and corporal bodies (CB) with IMRT preserves erectile function compared to standard IMRT in men with prostate cancer.117 patients with low-intermediate risk, clinical T1a-T2c prostate adenocarcinoma were enrolled to a single-institution, prospective, single blind, phase III randomized trial. All received definitive IMRT to 74-80 Gy in 37-40 fractions and standard IMRT (s-IMRT) or erectile tissue sparing IMRT (ETS-IMRT), which placed additional planning constraints that limited the D90 to the PB and CB to = 15 Gy and = 7 Gy, respectively. Erectile potency was assessed with components of the International Index of Erectile Function (IIEF) and PDE5 medication records.62 patients received ETS-IMRT and 54 received s-IMRT; 1 patient did not receive radiation therapy. Prior to treatment, all patients reported erectile potency. No patients received androgen deprivation therapy. In the intention-to-treat analysis, treatment arms did not differ in potency preservation at 24 months (37.1% ETS-IMRT vs 31.5% s-IMRT, p=0.53). Of 85 evaluable patients with IIEF and PDE5 medication follow-up, erectile potency was seen in 47.9% of patients in the ETS-IMRT arm and 46.0% of patients in the s-IMRT arm (p=0.86). PDE5 inhibitors were initiated in 41.7% of ETS-IMRT patients and 35.1% of s-IMRT patients (p=0.54). Among all patients enrolled, there was no difference in freedom from biochemical failure between those treated with ETS-IMRT and s-IMRT (5-yr 91.8% vs 90.7%, respectively, p=0.77) with a median follow-up of 7.4 years. There were no differences in acute or late GI or GU toxicity. An unplanned per-protocol analysis demonstrated no differences in potency preservation or secondary endpoints between patients who exceeded erectile tissue-sparing constraints and those who met constraints, though power was limited by attrition and unplanned dosimetric crossover.Erectile tissue sparing IMRT that strictly limits dose to the penile bulb and corporal bodies is safe and feasible. Use of this planning technique did not show an effect on potency preservation outcomes at 2 years, though power to detect a difference was limited.

View details for DOI 10.1016/j.ijrobp.2022.12.008

View details for PubMedID 36566906