title: Vessel-sparing Radiotherapy for Localized Prostate Cancer to Preserve Erectile Function: A Single-arm Phase 2 Trial.
abstract: Erectile dysfunction remains the most common side effect from radical treatment of localized prostate cancer. We hypothesized that the use of vessel-sparing radiotherapy, analogous to the functional anatomy approach of nerve-sparing radical prostatectomy (RP), would improve erectile function preservation while maintaining tumor control for men with localized prostate cancer.
  
  
  
  To determine erectile function rates after vessel-sparing radiotherapy.
  
  
  
  Men with localized prostate cancer were enrolled in a phase 2 single-arm trial (NCT02958787) at a single academic center.
  
  
  
  Patients received vessel-sparing radiotherapy utilizing a planning MRI and MRI-angiogram to delineate and avoid the erectile vasculature.
  
  
  
  Both physician- and patient-reported inventories were used to capture erectile function at baseline and at 2 and 5 yr after treatment. Validated model-based comparisons were performed to compare vessel-sparing results to nerve-sparing RP and conventional radiotherapy.
  
  
  
  From 2001 to 2009, 135 men underwent vessel-sparing radiotherapy. After a planned interim analysis, the trial was stopped after meeting the primary endpoint. The median follow-up was 8.7 yr, with a ≥94% response rate to all inventories at each time point. At 5 yr, 88% of patients were sexually active with or without the use of sexual aids. The 2-yr erectile function rates were significantly improved with vessel-sparing radiotherapy (78%, 95% confidence interval [CI] 71-85%) compared to modeled rates for convention radiotherapy (42%, 95% CI 38-45%; p<0.001) or nerve-sparing prostatectomy (24%, 95% CI 22-27%; p<0.001). At 2 yr after treatment, 87% of baseline-potent men retained erections suitable for intercourse. The 5- and 10-yr rates of biochemical relapse-free survival were 99.3% and 89.9%, and at 5 yr the biochemical failures were limited to the National Comprehensive Cancer Network high-risk group. The single-arm design is a limitation.
  
  
  
  Vessel-sparing radiotherapy appears to more effectively preserve erectile function when compared to historical series and model-predicted outcomes following nerve-sparing RP or conventional radiotherapy, with maintenance of tumor control. This approach warrants independent validation.
  
  
  
  In this interim analysis we looked at using a novel approach to spare critical erectile structures to preserve erectile function after prostate cancer radiotherapy. We found that almost 90% of patients at 5 yr after treatment remained sexually active, significantly higher than previous studies with surgery or radiotherapy.
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Spratt
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Jae Y
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Dess
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Vrinda
authors.initials: V
authors.lastname: Narayana
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Evans
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Liss
authors.affiliation: Department of Urology, Providence Cancer Center, Southfield, MI, USA.
authors.forename: Raymond
authors.initials: R
authors.lastname: Winfield
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA; Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Schipper
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Theodore S
authors.initials: TS
authors.lastname: Lawrence
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA; Department of Radiation Oncology, Providence Cancer Center, Southfield, MI, USA. Electronic address: mclaughb@umich.edu.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: McLaughlin
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D000368:Aged; D018572:Disease-Free Survival; D006801:Humans; D018783:Impotence, Vasculogenic / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D018810:Magnetic Resonance Angiography; D008297:Male; D008824:Michigan; D008875:Middle Aged; D059351:Organ Sparing Treatments / Q000009:adverse effects / Q000379:methods*; D010410:Penile Erection; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome
keywords: Erectile dysfunction; Prostate cancer; Radiotherapy; Vessel-sparing radiation