Vessel-sparing Radiotherapy for Localized Prostate Cancer to Preserve Erectile Function: A Single-arm Phase 2 Trial

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.

European urology. 2017 Feb 20 [Epub ahead of print]

Daniel E Spratt, Jae Y Lee, Robert T Dess, Vrinda Narayana, Cheryl Evans, Adam Liss, Raymond Winfield, Matthew J Schipper, Theodore S Lawrence, Patrick W McLaughlin

Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA., Department of Urology, Providence Cancer Center, Southfield, MI, USA., Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA; Department of Biostatistics, University of Michigan, Ann Arbor, MI, USA., Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA; Department of Radiation Oncology, Providence Cancer Center, Southfield, MI, USA. Electronic address: .