Functional Outcomes after Radiation Therapy or Radical Prostatectomy with Postoperative Radiation Therapy for High-Risk Prostate Cancer

Abstract

<h3>Purpose/Objective(s)</h3> The use of radical prostatectomy (RP) for men with high-risk prostate cancer (PC) is increasing. RP is often utilized as a component of multi-modality therapy, as a method to intensify treatment. Many patients who undergo RP will subsequently require radiation therapy (RT), exposing patients to side effects from both treatments. While the side effects of RT and RP have been directly compared in previous studies, there is limited data comparing side effects of primary RT with those of patients undergoing RP and RT (RP/RT). We hypothesize that patients undergoing RP/RT for high-risk PC will experience significantly higher side effects than those undergoing primary RT. <h3>Materials/Methods</h3> We used the Surveillance Epidemiology and End Results (SEER) database with Medicare insurance claims to identify patients 66 years or older with primary high-risk PC who underwent RP, RT, or both between January 1, 2004 and December 31, 2013. High-risk PC was defined as disease meeting one or more of the following criteria: stage ≥ T3a, grade group ≥ 4, PSA >20. Outcomes of interest included treatment for urinary incontinence, urethral stricture, erectile dysfunction (ED), proctitis and cystitis at least 1 year after completion of primary prostate cancer treatment, which were captured using diagnosis and procedure codes. Rates of these endpoints were compared using cumulative incidence functions as well as cox proportional hazard models. Patients who were lost to follow up or died were censored at the time of their last encounter. <h3>Results</h3> The cohort included 17,649 patients, of which 15,399 were treated with primary RT (87.25%) and 2,250 were treated with RP/RT (12.75%). On multivariable analysis, compared to primary RT, RP/RT was associated with an increased risk of incontinence therapy [HR 1.907 (1.679-2.166)], stricture therapy [HR 1.865 (95% CI: 1.589-2.190)] and ED therapy [HR 2.869 (95% CI: 2.046-4.023)] after treatment for prostate cancer. Rates of therapy for cystitis or proctitis were not significantly different between these two groups. <h3>Conclusion</h3> For men with high-risk PC, treatment with RP/RT was associated with increased utilization of incontinence therapy, stricture therapy, and ED therapy after completion of prostate cancer treatment. With multiple curative treatment options and long duration of survival after treatment, the side effect profile of treatment is a major factor in determining the most appropriate course of treatment for an individual patient. Patients considering primary RP as a component of multimodality therapy for high-risk PC should be informed about the increased risk of side effects. Clinical trials are required to better evaluate this treatment paradigm.