MP53-18 EFFICACY OF LOCAL TREATMENT IN PROSTATE CANCER PATIENTS WITH CLINICALLY PELVIC LYMPH NODE-POSITIVE DISEASE AT INITIAL DIAGNOSIS

Abstract

Abstract Background There is limited evidence supporting the use of local treatment (LT) for prostate cancer (PCa) patients with clinically pelvic lymph node-positive (cN1) disease. Objective To examine the efficacy of any form of LT±androgen deprivation therapy (ADT) in treating these individuals. Design, setting, and participants Using the National Cancer Database (2003–2011), we retrospectively identified 2967 individuals who received LT±ADT versus ADT alone for cN1 PCa. Only radical prostatectomy (RP) and radiation therapy (RT) were considered as definitive LT. Intervention LT±ADT versus ADT alone. Outcome measurements and statistical analysis Instrumental variable analyses (IVA) were performed using a two-stage residual inclusion approach to compare overall mortality (OM)-free survival between patients who received LT±ADT versus ADT alone. The same methodology was used to further compare OM-free survival between patients who received RP±ADT versus RT±ADT. Results and limitations Overall, 1987 (67%) and 980 (33%) patients received LT±ADT and ADT alone, respectively. In the LT±ADT group, 751 (37.8%) and 1236 (62.2%) patients received RP±ADT and RT±ADT, respectively. In IVA, LT±ADT was associated with a significant OM-free survival benefit (hazard ratio=0.31, 95% confidence interval [CI]=0.13–0.74, p =0.007), when compared with ADT alone. At 5 yr, OM-free survival was 78.8% (95% CI: 74.1–83.9%) versus 49.2% (95% CI: 33.9–71.4%) in the LT±ADT versus ADT alone groups. When comparing RP±ADT versus RT±ADT, IVA showed no significant difference in OM-free survival between the two treatment modalities (hazard ratio=0.54, 95% CI=0.19–1.52, p =0.2). Despite the use of an IVA, our study may be limited by residual unmeasured confounding. Conclusions Our findings show that PCa patients with clinically pelvic lymph node-positive disease may benefit from any form of LT±ADT over ADT alone. While not necessarily curative by itself, the use of RP or RT could be the first step in a multi-modality approach aiming at providing the best cancer control outcomes for these individuals. Patients summary We examined the role of local treatment for clinically pelvic lymph node-positive prostate cancer. We found that the delivery of radical prostatectomy or radiation therapy may be associated with an overall mortality-free survival benefit compared with androgen deprivation therapy alone.