Variation in the Use of Postoperative Radiotherapy Among High-risk Patients Following Radical Prostatectomy

TM Morgan; SR Hawken; KR Ghani; DC Miller; FY Feng; SM Linsell; JA Salisz; Y Gao; JE Montie; ML Cher

Disclosures

Prostate Cancer Prostatic Dis. 2016;19(2):216-221. 

In This Article

Abstract and Introduction

Abstract

Background: We used data from the Michigan Urological Surgery Improvement Collaborative (MUSIC) to investigate the use of adjuvant and salvage radiotherapy (ART, SRT) among patients with high-risk pathology following radical prostatectomy (RP).

Methods: For patients with pT3a disease or higher and/or positive surgical margins, we examined post-RP radiotherapy administration across MUSIC practices. We excluded patients with <6 months follow-up, and those that failed to achieve a postoperative PSA nadir ≤0.1. ART was defined as radiation administered within 1 year post RP, with all post-nadir PSA levels <0.1 ng ml−1. Radiation administered >1 year post RP and/or after a post-nadir PSA ≥0.1 ng ml−1 was defined as SRT. We used claims data to externally validate radiation administration.

Results: Among 2337 patients undergoing RP, 668 (28.6%) were at high risk of recurrence. Of these, 52 (7.8%) received ART and 56 (8.4%) underwent SRT. Patients receiving ART were younger (P=0.027), more likely to have a greater surgical Gleason sum (P=0.009), higher pathologic stage (P<0.001) and received treatment at the smallest and largest size practices (P=0.011). Utilization of both ART and SRT varied widely across MUSIC practices (P<0.001 and P=0.046, respectively), but practice-level rates of ART and SRT administration were positively correlated (P=0.003) with lower ART practices also utilizing SRT less frequently. Of the 88 patients not receiving ART and experiencing a PSA recurrence ≥0.2 ng ml−1, 38 (43.2%) progressed to a PSA ≥0.5 ng ml−1 and 20 (22.7%) to a PSA ≥1.0 ng ml−1 without receiving prior SRT. There was excellent concordance between registry and claims data κ=0.98 (95% CI: 0.94–1.0).

Conclusions: Utilization of ART and SRT is infrequent and variable across urology practices in Michigan. Although early SRT is an alternative to ART, it is not consistently utilized in the setting of post-RP biochemical recurrence. Quality improvement initiatives focused on current postoperative radiotherapy administration guidelines may yield significant gains for this high-risk population.

Introduction

Although three prospective randomized clinical trials have evaluated the impact of adjuvant radiotherapy (ART) on long-term outcomes following radical prostatectomy (RP), there is no consensus surrounding its use. These phase 3 trials—SWOG 8794, EORTC 22911 and ARO 96-02—have all reported results after more than 10 years of follow-up, and each study demonstrated significantly lower rates of biochemical progression with ART compared with the control arm.[1–3] However, the results were mixed, and in some cases conflicting, regarding more distant end points such as metastasis-free and overall survival. For example, in contrast to EORTC 22911 and ARO 96-02, SWOG 8794 is the only trial to have demonstrated improved overall survival with ART. These studies were somewhat heterogeneous, though, with one-third of patients in the SWOG and EORTC studies having a PSA >0.2 ng ml−1 at study entry. In addition, salvage radiotherapy (SRT) was not mandated in the control arm in any of these studies and was often given later than would typically be recommended or not at all.

As a result, there are few guidelines surrounding the administration of postoperative radiation in patients at high-risk of local recurrence after RP. According to European Association of Urology (EAU) guidelines, patients at high risk of local failure (defined by positive surgical margin or seminal vesicle invasion) should be offered either immediate ART or early SRT at a PSA ≤0.5 ng ml−1.[4] Combined guidelines from the American Urological Association and American Society for Radiation Oncology state that high-risk patients (defined by the presence of positive surgical margins, extraprostatic extension or seminal vesicle invasion) should be offered ART but make no recommendation that it be given.[5] In the absence of strong recommendations in favor of ART, and given concerns surrounding overtreatment, urologists have tended not to recommend ART, with a recent study of the National Cancer Database reporting a rate of 9.9% in a high-risk cohort.[6] However, beyond similar population-based and single-institution studies, there is little data regarding how post-RP radiotherapy is utilized in high-risk patients.

In this study, we aimed to understand the real-world administration of ART and SRT in men at high risk of local recurrence following RP. Given the lack of consensus surrounding postoperative radiation in these patients, we hypothesized that rates of ART and SRT would be highly variable across practices. Using data from the Michigan Urological Surgery Improvement Collaborative (MUSIC), encompassing nearly 85% of urologists in the state of Michigan, we sought to quantify the variation in management according to patient and tumor characteristics and across MUSIC practices.

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