Presentation Authors: Nikola Rakic*, Audrey Fotouhi, Lee Baumgarten, Alex Borchert, Deepansh Delela, Akshay Sood, Sohrab Arora, Jacob Keeley, Mani Menon, Firas Abdollah, Detroit, MI
Introduction: Three trials showed the benefit of adjuvant radiotherapy (aRT) in patients with adverse pathological features at the time of RP. Additionally, recent data showed that patients with very aggressive features benefit the most from aRT. We set to examine the utilization and impact on overall survival (OS) of aRT over the last decade in patients with adverse pathological features.
Methods: We identified 189,240 prostate cancer patients with adverse features at RP (positive margin, pT3a or higher, and/or pN1 disease), who were treated between 2004 and 2015, within the NCDB. We first examined the utilization of aRT in these patients , and tested for changes over time. We then propensity-score matched patients who received aRT to their counterparts, who received no aRT and evaluated the impact of aRT on OS using cox regression analysis. Finally, we focused on patients with very aggressive features (at least two of: pT3b or higher, pathological Gleason 8-10, and pN1), and repeated the aforementioned analyses.
Results: In patients with adverse features, only 11.7% (22,320) received aRT. This rate changed from 12.9% in 2004 to 12.2% in 2015 (p=.009). Likewise, of 20,583 patients with very aggressive features, only 28.9% (5967) received aRT. This rate changed from 27.9% in 2004 to 29.6% in 2015 (p=.4). In patients with any adverse pathology, the 120-month OS was 72.0% in aRT patients vs. 72.4% in patients without aRT (p=.3). In patients with very aggressive features, this rate was 56.6% in aRT patients vs. 53.7% in patients without aRT (p=.008). In patients with adverse pathological features, aRT was not an independent predictor of OS (HR: 1.01 95% CI 0.94-1.08 p-value: .6). Conversely, in individuals with very aggressive pathological features, aRT patients had more favorable OS compared to their non-aRT counterparts (HR: 0.88 95% CI, 0.80-0.98, p-value: .01).
Conclusions: On a national level, there is a severe under-utilization of aRT, which did not improve over time. This is true even in patients with very aggressive pathological features. This indicates a sub-optimal quality of care, especially given the evident survival benefit of aRT in these patients. While an aRT survival benefit was not evident in our cohort of patients with any adverse pathological features, this might be due to the severe selection bias against aRT in clinical practice. Our findings highlight a quality-of-care concern, and indicate that urgent efforts are needed to improve the current practice pattern in the United States.