Presentation Authors: Huang Wei Su, Linda M Huynh, Orange, CA, Stephen B. Williams, Galveston, TX, Thomas Ahlering*, Orange, CA
Introduction: For patients undergoing radical prostatectomy for primary treatment of localized prostate cancer, adjuvant radiotherapy (ART) is indicated by NCCN guidelines when they have poor pathologic characteristics, such as seminal vesicle invasion, extraprostatic extension, positive surgical margin and pathologic Gleason 8-10. We seek to assess salvage radiotherapy (SRT) to reduce the cost and overtreatment on radiotherapy.
Methods: Between 2002 and 2015, 1460 men underwent RARP as primary treatment for localized prostate cancer. Patients without PSA follow-up (N=40) were excluded. Biochemical recurrence (BCR) was defined as PSA>0.2 ng/ml after RP. Likelihood of ART treatment per NCCN guidelines, BCR, prostate cancer specific mortality (PCSM) and overall mortality (OM) were the outcomes. 2016 Medicare reimbursement rates were used to estimate cost of secondary interventions.
Results: BCR occurred in 321 (21.99%) patients; at a median follow-up data of 4.9 years. 81% had follow-up PSA over 2 years. Per NCCN guidelines, 532(36.44%) men were indicated to undergo ART. However, of these men, only 240 (45.11%) had BCR and 17 (1.16%) of them went through ART; the remainder had no evidence of disease. Despite the low proportion of patients undergoing ART, the overall and prostate cancer specific mortality in this cohort are similar to others: 84(5.75%) and 23 (1.58%), respectively. At a Medicare expense of $37,000 per ART treatment, treating per NCCN guidelines would result in a surplus of $10 million for the treatment of patients with no evidence of disease.
Conclusions: 69-71% is the range of risk that patients who have unfavorable pathological features may be over treated by ART. Previous reports of SRT have similar outcomes and may reduce the cost that are supported by these outcomes. The results of this study can provide a fundamental evidence for future trials on utilization of SRT.