Genitourinary Cancer

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SU_28_2290 - Intermediate-Term versus Longer-Term Androgen-Deprivation Therapy for High-Risk Prostate Cancer Treated with High Dose Radiation: 12-Year Outcomes Data

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Intermediate-Term versus Longer-Term Androgen-Deprivation Therapy for High-Risk Prostate Cancer Treated with High Dose Radiation: 12-Year Outcomes Data
S. Lazarev1, M. R. Thompson1, L. Resende Salgado1, N. N. Stone2, and R. G. Stock3; 1Icahn School of Medicine at Mount Sinai Department of Radiation Oncology, New York, NY, 2Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY, 3Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, NY

Purpose/Objective(s): Optimal duration of androgen-deprivation therapy (ADT) for high-risk prostate cancer (HRPC) treated with high biologically effective dose (BED) radiation (i.e. external beam radiotherapy (EBRT) with brachytherapy boost) is not well-defined. Findings of ASCENDE-RT trial suggested favorable outcomes with 12 months of ADT for both intermediate- and high- risk PC. Data on further de-intensification of ADT in the setting of HRPC treated with high dose RT are limited. In this study we aimed to assess outcomes after an intermediate-term (9 months) vs longer-term (>9 months) ADT for HRPC treated with combined regimen (i.e. EBRT and brachytherapy).

Materials/Methods: We identified 375 men with NCCN-defined HRPC treated with combined regimen and ≥9 months of ADT in our institution in the period 1990-2016. Among these patients, 286 (76%) received intermediate-term (IT, 9 months) and 89 (24%) – longer-term (LT, >9 months) ADT. Primary study endpoints were biochemical failure-free survival (BFFS), distant metastases-free survival (DMFS), and overall survival (OS). Survival was examined using the log-rank test, Kaplan-Meier method, and Cox regression modeling.

Results: The median age at diagnosis for all patients was 69 years. The median cumulative BED was 204 Gy (range, 174 – 237 Gy). 13% of patients treated with IT vs 24% with LT ADT had stage≥T3a, p=0.05; 73% treated with IT vs 79% with LT ADT had Gleason Score (GS) >7, p<0.07; 32% treated with IT vs 47% with LT ADT had PSA>20, p<0.0001. The median duration of LT ADT was 24 months (range, 12-26 months). At a median follow-up of 6.2 years, a total of 73 (19%) patients developed biochemical failure, and 33 (9%) – distant metastases. 78 (21%) deaths were recorded, none of which were due to prostate cancer. The overall 12-year rates for BFFS, DMFS, and OS were 69%, 85%, 60%, respectively. The 10- and 12-year BFFS rates were 72% and 72% with IT vs 66% and 55% with LT ADT (p=0.47). The 10- and 12-year DMFS rates were 88% and 86% with IT vs 80% and 80% with LT ADT (p=0.53). The 10- and 12-year OS rates were 66% and 59% with IT vs 68% and 68% with LT ADT (p=0.50). Multivariate analyses (MVA) found no difference in OS (HR 0.64, p=0.25), DMFS (HR 1.09, p=0.85), or BFFS (HR 1.15, p=0.65) between IT and LT ADT. Furthermore, on MVA, stages T2b-T2c, GS>7, and PSA >20 were associated with worse BFFS, whereas PSA >20 was associated with worse DMFS. Stages T3a-T3b and PSA >20 predicted worse OS.

Conclusion: In the present HRPC analysis, patients treated with IT ADT had a slightly more favorable disease with respect to stage and PSA, as compared with those treated with LT ADT. In this context, IT ADT administered in conjunction with the high BED RT yielded comparable biochemical control and survival. Select patients with HRPC treated with EBRT plus LDR-BT boost should be considered for an intermediate course (9 months) of ADT. Hormonal therapy beyond 9 months should be reserved for patients with more advanced HRPC and/or high PSA at presentation.

Author Disclosure: S. Lazarev: None. M.R. Thompson: None. L. Resende Salgado: None. R.G. Stock: Independent Contractor; BARD. Honoraria; BARD.

Stanislav Lazarev, MD

Mount Sinai Health System

Biography:
I am currently a Chief Resident in Radiation Oncology at Mount Sinai Hospital in New York, NY. My research interests lie in the field of head and neck malignancies, pediatric tumors, LDR-brachytherapy for prostate cancer, and SBRT for hepatocellular carcinoma. My clinical interests are broad, and include treatment of pediatric malignancies, gynecologic, head and neck, and gastrointestinal cancers.

I grew up in the south of Russia where I studied foreign languages at a linguistic university. At the age of 21, I moved to California where in 2009 I graduated from UC Berkeley with a BA in biochemistry and molecular biology. I received my medical degree at University of Vermont College of Medicine in 2014, and then returned to the Bay Area to complete a medicine internship at Highland Hospital in Oakland. In 2015 I joined the Radiation Oncology Residency Program at Mount Sinai. Outside of medicine, I enjoy learning foreign languages, playing the piano, traveling abroad, and playing soccer.

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