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208 Background: Treatment of high risk prostate cancer (HRPCa) with external beam radiotherapy (EBRT) plus brachytherapy (BT) boost (EBRT+BT) has been prospectively associated with lower rates of BCR, albeit potentially with increased toxicity, and retrospectively linked to decreased distant metastasis (DM) and PCa-specific mortality (PCSM) compared to EBRT alone. However, it is unclear whether patients who develop BCR following either approach have similar downstream oncologic outcomes. Methods: We identified 706 out of 3820 men with HRPCa treated at 13 institutions from 1998-2015 with EBRT (n=468/2134) or EBRT+BT (n=238/1686) who developed BCR. We compared rates of DM, PCSM, and all-cause mortality (ACM) after BCR between treatment groups using Fine-Gray competing risk regression. Models were adjusted for age, Gleason grade group, initial PSA (iPSA), clinical T stage, time-dependent use of systemic salvage, and interval to BCR using inverse probability of treatment weighting. Results: Median follow-up was 9.9 years from RT and 4.8 years from BCR. Groups were similar in age, iPSA, presence of ≥2 HR features, and median interval to BCR (3.3 years). Most men received neoadjuvant/concurrent androgen deprivation therapy (ADT), 92.5% and 91.0% for EBRT and EBRT+BT, respectively, though for a longer duration with EBRT (median 14.7 vs. 9.0 months, p=0.0012). Local and systemic salvage rates were 2.3% and 36.3% after EBRT, and 2.6% and 43.6% after EBRT+BT, respectively. Initial EBRT+BT was associated with significantly lower rates of DM after BCR (HR 0.48, 95% CI 0.36-0.64, p

109 Background: While level one evidence has shown an overall survival (OS) advantage with the addition of androgen deprivation therapy (ADT) to radiotherapy (RT) for intermediate risk prostate cancer (PCa), the benefit in the era of modern dose escalation is controversial, especially given the heterogeneity within this risk group. We assessed the impact of adding ADT to high dose RT on OS for intermediate risk PCa stratified by number of intermediate risk factors (IRF). Methods: We identified 114,339 men with intermediate risk PCa (Gleason 7, clinical stage T1-2, PSA < 20 ng/mL) using the National Cancer Database. Men were stratified into the following subgroups based on the number of IRFs (Gleason 7, cT2b-c, PSA > 10-20 ng/mL): A) Gleason 3+4 and no other IRF, B) Gleason 4+3 and no other IRF, C) two IRFs, and D) three IRFs. The addition of ADT to dose-escalated external beam RT (DE-EBRT, ≥ 75.6 Gy), brachytherapy (BT), or combination EBRT+BT on OS was assessed within each subgroup using Kaplan-Meier and log-rank tests in propensity score-matched cohorts in all men and subsequently only in those with Charlson-Deyo comorbidity index (CDI) of zero. Results: There was no OS benefit with the addition of ADT to DE-EBRT, BT, or EBRT+BT in groups A, B, and C, even after limiting the cohort to men with CDI = 0. However, in group D, the addition of ADT to DE-EBRT was associated with a trend for OS improvement in patients with CDI = 0 only (8-year OS with and without ADT 68.3% and 62.4%, respectively, log-rank P= .07). Conversely, there was a trend for OS decrement with the addition of ADT to DE-EBRT in men with CDI ≥ 1 (8-year OS with and without ADT 61.8% and 67.5%, respectively, log-rank P= .06). There was no OS benefit of ADT in group D treated with BT or EBRT+BT, regardless of comorbidity status. Conclusions: The OS benefit of ADT in men with intermediate risk PCa may be limited to those with 3 IRFs and minimal comorbidities treated with DE-EBRT. If prospectively validated, extreme dose escalation achieved with BT (alone or in combination with EBRT) may obviate the addition of ADT in all men with intermediate risk disease, especially in an era of advanced molecular imaging.

102 Background: Patients with Gleason score (GS) 9-10 prostate cancer (PCa) have a high risk of early biochemical recurrence (BCR). Salvage therapy options differ depending on the upfront management strategy. Patients who received upfront surgery (RP) may be curable with salvage external beam radiation therapy (EBRT). However those who underwent EBRT or EBRT with a brachytherapy boost (EBRT+BT) are less likely to receive local salvage therapy and are commonly treated with androgen deprivation therapy (ADT). In this study, we examine the risk of distant metastases (DM) and prostate-cancer specific mortality (PCSM) among patients with GS 9-10 PCa who had BCR following RP, EBRT, or EBRT+BT. Methods: 712 patients with GS 9-10 PCa treated between 2000-2013 at 12 institutions who had BCR were included (346 RP, 282 EBRT, 84 EBRT+BT). Time to DM and PCSM were compared between groups using Cox proportional hazards models with propensity score adjustment. Propensity scores were calculated using age, T-stage, PSA, and GS. Results: In patients who had a BCR, incidence rates of DM and PCSM after RP were 40% and 28%. Rates after EBRT were 60% and 46% and after EBRT+BT were 49% and 31%. Median times to DM and PCSM were 3.5 and 4.9 years after RP, 3.7 and 5.1 years after EBRT, and 3.3 and 6.8 years after EBRT+BT. The rates of local salvage RT and systemic salvage therapy among RP patients were 38% and 59%, respectively. Local and systemic salvage rates were 5% and 31% for EBRT patients and 5% and 28% for EBRT+BT patients. EBRT patients had a shorter time interval to DM compared with RP (HR 1.4, p = .02) and EBRT+BT (HR 1.9, p < .01). EBRT patients also had a shorter time interval to PCSM compared with RP (HR 1.5, p = .02). Conclusions: Among patients with GS 9-10 PCa who experience BCR after definitive management, those treated with EBRT have a shorter time interval to DM and PCSM compared with RP and EBRT+BT. While this analysis is confounded by the differential thresholds for diagnosing a BCR after different modalities, it does suggest that outcomes following BCR after EBRT+BT and RP are similar. It also suggests that extreme dose escalation delays the onset of DM and PCSM even after BCR, when compared with conventionally-dosed EBRT alone.

53 Background: The costs of treating localized, Gleason score 9 and 10 prostate cancer remain poorly described, especially when the particularly aggressive nature of the disease often requires a multimodal approach. We report the results of time-driven activity-based costing to assess the long-term costs of treating this subset of patients with either RALP, high-dose EBRT, or EBRT with a high-dose rate brachytherapy (BT) boost. Methods: Based on a multi-institutional cohort of 487 patients with Gleason score 9-10 prostate cancer, we generated process maps for each phase of care from the initial urologic visit through a median follow-up of 3.76 years, incorporating all prostate cancer treatment over this horizon. Costs were calculated per unit time, and the proportion of capacity for each step was determined. TDABC was defined as the sum of its resources. Results: Substantial cost variation was demonstrated between treatment modalities with an estimated median cost of $49,681 for EBRT, $35,140 for RALP, and $31,647 for EBRT + BT at 3.76 years. The primary driver in cost variation was the use of ADT. RALP (170 pts) ranged from $18,896 (29.5%) for no postoperative therapy to $63,270 for immediate long-term ADT (5.3%). EBRT (230 pts) had the greatest cost variation [Table 1]. Finally, EBRT + BT (336 pts) ranged from $26,522 for EBRT + BT alone (12.6%) to $37,834 for EBRT + BT + salvage ADT + HIFU (1.2%). Conclusions: Characterizing the costs associated with the distribution of treatments for men with high-risk prostate cancer is essential as we move towards health care accountability. There is substantial long-term cost variation between treatments in this subset of patients, and understanding these differences may affect treatment implications as we shift toward accountable payment models.[Table: see text]

Table 1. Patient Characteristics (N=40) Median Follow-up (range in months) 35 (7-120) Median Age (range) 62 (38-79) Surgical Staging (# of pts) 39 Histology (# of pts) Endometrioid Adenocarcinoma 13 (32.5%) Papillary Serous 15 (37.5%) Clear Cell 11 (27.5%) Undifferentiated 1 (2.5%) Adjuvant Treatment (# of pts) Combined Chemotherapy and Radiation 23 EBRT+ VC 11 (3 extended field) EBRT only 8 (4 extended field) VC only 3 Chemotherapy or Radiation Alone (# of pts) 17 Chemotherapy alone (# of pts) 9 Radiation alone (# of pts) 8 EBRT+ VC 3 EBRT only 4 (2 extended field) VC only 1 Materials/Methods The optimal management of high-risk endometrial cancer has yet to be determined. A retrospective review was undertaken to determine whether adjuvant therapy with combined chemotherapy and radiation (CRT) versus either chemotherapy or radiation therapy alone (C/RT) impacts clinical outcomes. Figure 1 Local Failure (LF)