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497 Background: Bacillus Calmette-Guerin (BCG) is currently recommended as adjuvant therapy following complete transurethral resection of bladder tumor (TURBT) for high-risk non-muscle invasive bladder cancer (NMIBC). However, continued BCG production shortages have precluded the use of BCG in many urologic practices. Efficacy of sequential intravesical gemcitabine and docetaxel (Gem/Doce) in the BCG failure setting has been reproduced across multiple institutions. In response to the continuing BCG shortage, Gem/Doce has been utilized at our institution in the BCG-naïve setting. We report the outcomes of a large cohort of patients with high-risk BCG-naïve NMIBC treated with Gem/Doce. Methods: We retrospectively identified all patients with BCG-naïve high-risk NMIBC who were treated with Gem/Doce from May 2013 through April 2021. We included patients with intent to receive 6 weekly intravesical instillations of sequential 1 gram gemcitabine and 37.5mg docetaxel after complete TURBT. Monthly maintenance of 2 years was initiated if disease free at first follow-up. The primary outcome was recurrence-free survival (RFS) and efficacy was evaluated in an intention-to-treat manner. Recurrence was defined as pathologically confirmed tumor relapse in the bladder or prostatic urethra. Progression was defined as T-stage increase from Ta or CIS to T1 or development of muscle invasive or metastatic disease. Survival was assessed using the Kaplan-Meier method and log rank test, indexed from the first Gem/Doce instillation. Results: One hundred seven patients with median follow-up of 15 months were included in the analysis. There were 47 with any CIS, 55 with T1 disease, and 7 with micropapillary variant histology. Four patients did not complete a full induction cycle due to hematuria (3) and severe frequency/nocturia (1). 19 patients sustained a recurrence at any point during follow-up. RFS was 89%, 85%, and 82% at 6, 12, and 24 months, respectively. No difference in RFS was seen in patients with or without CIS (p = 0.42). No patients met criteria for either form of disease progression. One patient underwent cystectomy due to end-stage lower urinary tract symptoms, with final pathology pTisN0. No patients died of bladder cancer. Overall survival was 84% at 24 months. 46 patients reported any symptoms during treatment. Common side effects included urinary frequency/urgency (36%), hematuria (11%), and dysuria (8%). Conclusions: In a large cohort of high-risk, BCG-naïve NMIBC patients, Gem/Doce showed excellent efficacy (84% 2-year HG-RFS). These rates are similar to modern treatment naïve cohorts receiving BCG. Prospective comparative analysis of Gem/Doce in BCG-naïve populations is warranted.[Table: see text]

496 Background: Intravesical gemcitabine-docetaxel (Gem/Doce) has emerged as an efficacious and well-tolerated therapy for NMIBC. At first cytoscopic evaluation, success rate for BCG failures is 75-80% with 60% of responders remaining disease free at 24 months. Success rates are even higher for BCG naïve patients with close to 90% disease free at 3 months, and 93% of responders HG disease free at 24 months. There is an unmet need for effective bladder-sparing regimens for Gem/Doce failures. FDA-approved agents in this setting have poor long-term efficacy; Valrubicin has an 8% 24-month disease free rate, and recently approved Pembrolizumab has less than 20% complete response at 1 year. Based on poor efficacy of alternatives, we evaluated sequential intravesical valrubicin-docetaxel (Val/Doce) as a rescue therapy for NMIBC. Methods: We retrospectively identified all patients with NMIBC who were treated with Val/Doce between April 2013 and June 2021. Patients were included with intent to receive 6 weekly intravesical instillations of sequential 800 mg valrubicin and 37.5 mg docetaxel after complete TURBT. Monthly maintenance of 2 years was initiated if disease free at 3-month cytoscopic evaluation. The primary outcome was recurrence-free survival (RFS). Progression events included the development of muscle invasive or metastatic disease as well as any cystectomy. Survival was assessed using the Kaplan-Meier method and log rank test, indexed from start of Val/Doce induction. Surveillance was performed according to AUA guidelines. Results: The final cohort included 75 patients with median follow-up of 21 months. Of these patients, 12 were treated with Val/Doce for low-grade Ta disease, with 60% disease free at 2 years and no subsequent HG occurrences. The remaining 63 patients had high-grade disease of which 86% were BCG failures and 89% were Gem/Doce unresponsive. The 2 year RFS for high-grade patients was 39%. CIS was present in 56% of the cohort. RFS was similar for those with and without CIS. Progression occurred in 12 of the patients with high-grade disease. Of note, 10 underwent cystectomy and 2 died of metastatic bladder cancer, yielding a bladder cancer specific death rate of 3%. Overall and cystectomy-free survival was 88 and 85% at 24 months, respectively. The most commonly reported side effects were bladder spasms (24%), urinary frequency (13%), and dysuria (11%). There were 3 patients who could not tolerant a full induction course. Conclusions: Sequential intravesical valrubicin-docetaxel will rescue a substantial portion of patients with HG NMIBC failing Gem/Doce or BCG. Thus, the regimen allows a high proportion of patients ( > 80%) to retain their bladders with an acceptable ( < 20%) progression rate without succumbing to bladder cancer-related death ( < 5%).[Table: see text]

451 Background: Outside of Lynch syndrome, few genetic factors have been associated with urothelial cancer (UC). This project seeks to describe the frequency of germline variants in a multi-center UC cohort. Methods: Patients diagnosed with UC from 1980 to 2019 and consented to the Total Cancer Care protocol by members of the Oncology Research Information Exchange Network (ORIEN) were included in the study. The ORIEN program includes a convenience sample of cases with both germline and tumor samples available, though this analysis was germline only. Whole exome sequencing data were analyzed using a GATK best practices for germline variant analysis. A series of quality control (allele frequency > = 0.3, read depth > = 20, genotype quality > = 20), annotation, functional impact (loss of function/splicing), and region (cancer predisposition genes/pathways) filters were applied to identify variants of significant consequence. Results: 348 exomes were evaluated. This identified 60 variants classified as pathogenic/likely pathogenic (P/LP) and 17 novel, high impact variants in genes associated with high, moderate, or recessively inherited cancer risk in 77 individuals (22.1%). 15 (4.5%) had P/LP variants in genes associated with a high or moderate cancer risk, and 10 (3%) of these variants were considered to be clinically actionable with associated with cancer screening, risk reduction or treatment recommendations. The high/moderate risk genes with P/LP variants included CHEK2 (n = 5), FANCM (n = 4), MSH6 (n = 2) and single cases of MSH2, BRCA2, ERCC3, and BRIP1. The average age of diagnosis in those with and without a high/moderate risk P/LP variant was 67.6 (57-80 yrs) and 68.9 (45-91 yrs). Family history of cancer was reported for 73% of those with a germline LP/PV and 60% of those without, but this trend was not significant (p =.44). Conclusions: Individuals with UC have a high frequency of germline variants that warrant further study for association with cancer risk. A smaller, but significant portion also carry germline variants that may be clinically relevant to them and/or family members. Currently UC is not included in genetic testing criteria. This study adds to the growing body of research indicating that diverse types of cancer patients harbor germline variants. Strategies for expanding testing should be considered.

573 Background: Intravesical bacillus Calmette-Guérin (BCG) is the first-line treatment for high-risk non-muscle invasive bladder cancer (NMIBC). Unfortunately, disease recurrence/progression is common and associated with increased risk of death from bladder cancer. While radical cystectomy remains the preferred treatment for BCG unresponsive NMIBC, many patients are either unwilling or unfit to undergo surgery. Previous retrospective studies have demonstrated the efficacy of intravesical gemcitabine and docetaxel (Gem/Doce) for treating NMIBC after BCG failure. However, the long-term outcomes of this cohort are unknown. We report 5-year survival outcomes of patients treated with intravesical Gem/Doce after BCG failure. Methods: We retrospectively identified patients at our institution who were treated with Gem/Doce for high-risk NMIBC after BCG failure between 2009 and 2017. Patients received six weekly intravesical Gem/Doce instillations. Initial responders received monthly maintenance instillations for 2 years. Surveillance was performed according to American Urological Association guidelines. Survival time was measured from start of Gem/Doce induction. Outcomes included high-grade recurrence-free survival (HG-RFS), progression-free survival (PFS), cystectomy-free survival (CFS), cancer-specific survival (CSS) and overall survival (OS). Recurrence was defined as pathologically confirmed tumor relapse in the bladder or prostatic urethra. Progression was defined as recurrence of disease with stage T2 or greater, cystectomy or death due to bladder cancer. Survival probabilities were calculated with the Kaplan-Meier method. Results: A total of 97 patients with a median age of 73 years were treated with Gem/Doce after BCG failure. Median follow-up was 49 months. BCG failure was further stratified as BCG unresponsive (35%), BCG relapsing (38%), BCG intolerant (11%) or unspecified (16%). 71% and 21% of patients had carcinoma in-situ and high-grade T1 disease, respectively. Complete response at initial surveillance was 74% and median duration of response was 26 months. Overall HG-RFS at 1, 2 and 5 years was 60%, 51% and 31%, respectively. HG-RFS was similar among BCG unresponsive patients and the overall cohort (see table). During follow-up, 18 patients (19%) underwent radical cystectomy and 28 patients (29%) experienced disease progression. PFS, CFS, CSS and OS at 5 years was 68%, 75%, 91% and 64%, respectively. Conclusions: Intravesical Gem/Doce for high-risk NMIBC after BCG failure offers long-term efficacy and substantial durability of response with a high likelihood of bladder preservation at five years after induction. Future prospective trials assessing Gem/Doce are warranted.[Table: see text]

322 Background: Hypoxia induced factor 1α/2α (HIFs) and vascular endothelial growth factor (VEGF) are overexpressed in ccRCC and associated with increased tumor angiogenesis, vascular instability and drug resistance. In xenografts, high dose SLM resulted in sustained down regulation of HIFs, normalization of tumor vasculature that resulted in increased drug delivery, and therapeutic synergy with anti-VEGF therapeutic. These effects were highly SLM dose, sequence, and schedule dependent. Methods: After completion of the escalating phase I (3+3) trial, the non-toxic SLM dose of 4000μg was administered orally twice daily (BID) for 14 days, followed by once daily in combination with axitinib 5 mg BID. The primary endpoint is safety and the secondary end point include overall response rate (ORR), progression free survival (PFS), and overall survival (OS). To assess the potential effects of SLM on tumor vascular function, dual energy computed tomography (DECT) was conducted at baseline, day 14 of SLM, and at 3 months of SLM + axitinib. Results: Thirty subjects are screened. Of whom 25 have efficacy data (3 subjects screen failure, 1 withdrew, 1 taken off study prior to first scan due to progression with brain lesions likely present prior to study entry). 13/25 (52%) have confirmed response (CR/PR). Two subjects had CR lasting for at least 35 and 44 months, 6 subjects achieved stable disease (SD) lasting at least 6 months accounting for disease control rate (DCR) of 76%, mPFS is 9.5 months. 5/30 patients have sarcomatoid features, all of which are evaluable for efficacy with 1 PR achieved (20%). In the 20 patients without sarcomatoid features, 12/20 achieved PR (60%). The most prevalent adverse events (AE) included fatigue, diarrhea, anorexia, nausea, hoarseness, weight loss, and hypertension. No deaths nor grade 4 toxicities observed. The blood selenium concentrations achieved in the 4000μg SLM dose cohorts are similar to those determined molecularly and therapeutically synergistic with axitinib in xenografts and are being achieved clinically without significant toxicity. DECT data demonstrated increased iodine uptake by tumor lesions, but not in normal tissues, on day 14 SLM treatment and decreased in these same lesions at 3 months of SLM/axitinib. Conclusions: Blood selenium concentrations and duration of treatment seem to be critical determinants of response. Pre and concurrent treatment with SLM enhance the ORR and PFS of axitinib, with no additional toxicity. Currently documented responses are similar across IMDC risk groups. Clinical trial information: NCT02535533 .

634 Background: Response to checkpoint inhibitors (CPIs) for renal cell cancer (RCC) remains variable, with markers like PDL1 proving unreliable. Preclinical models suggest that obesity could affect CPI outcomes. We conducted a retrospective study on the effect of obesity on outcomes in RCC patients treated with CPIs. Methods: RCC patients treated with nivolumab +/- Ipilimumab at university of Alabama at Birmingham (UAB) and University of Iowa (UIOWA) from 2015 - 2018 were classified according to WHO standard definition of BMI as non-obese (NOB-30Kg/m2). Overall survival (OS) was defined as the interval from the first CPI dose to date of death or to last follow up date if patients were still alive. Progression free survival (PFS) was defined as the interval from the first dose of CPI to date of progression or date of death and censored at last follow-up date if patients were still alive without progression. Multivariable Cox proportional hazard regression model was used to evaluate the association between OS/PFS and obesity status, controlling for age, sex, race and number of prior therapies. All analyses were performed using SAS 9.4. Results: 84 patients with at least 6 months follow-up received a median of 9 doses of CPI with median follow of 72 weeks. 48 patients were NOB while 36 patients were OB, with 40 patients deceased at time of analysis. The most common response was stable disease in 45%, with CR in 5% and PR in 10% for a disease control rate of 63%. The median OS was 30 months in NOB patients and 20 months in the OB group. The 2 yr survival was 59% in the NOB group vs 28 % in the OB group with a HR of 0.60 (0.32-1.14; p=0.12). Median PFS was 13 months in the NOB group vs 7.3 months in the OB group with 2 yr PFS of 28% in the NOB group vs 5.5% in the OB group (HR 0.58 {0.35-0.98}; p=0.04). Conclusions: In this analysis of RCC patients treated with CPI, BMI < 30 predicts better OS and PFS. Further studies are required to better understand the effect of BMI on CPI outcomes in RCC.[Table: see text]

487 Background: Advanced bladder cancer is the most common malignancy of the urinary system with 5-year OS rates of 5-7%. Platinum based chemotherapy and checkpoint inhibitors are currently available treatment options but with limited benefit. We hypothesize that combining Avelumab (anti-PD-L1 immunotherapy) with Docetaxel is safe and will lead to cancer cell death releasing neoantigens with enhanced anti-tumor immune mediated cytotoxicity. Methods: This is a phase 1b, single arm, non-randomized, open label prospective clinical trial to evaluate the combination of Avelumab and Docetaxel in adult subjects with locally advanced or metastatic urothelial carcinoma with disease progression during or following platinum-containing chemotherapy, or within 12 months of neoadjuvant or adjuvant platinum-containing chemotherapy. It has two phases: Phase 1b dose de-escalation of docetaxel (Level 0: 75, Level -1: 60 or Level -2: 45 mg/m2) with standard dose avelumab (10 mg/kg) to establish phase 2 dose in the standard 3+3 design. In the dose expansion phase, the phase 2 dose of docetaxel with avelumab will be evaluated for efficacy. The combination therapy is administered every 3 weeks for 6 cycles and then avelumab alone is continued every 2 weeks. Primary endpoint is safety. Efficacy endpoints include objective response rate, progression free survival and overall survival. Results: At the cutoff date of 10/21/2019, 10 eligible patients were enrolled in the study. Only one of the six patients treated with level 0 dose of docetaxel had a dose limiting toxicity (neutropenic fever). Docetaxel at 75 mg/m2 along the avelumab was deemed safe for dose expansion cohort. Additional 4 patients were enrolled in the dose expansion cohort. Efficacy data is preliminary with 1 patient achieving CR, 2 pts had PR, 2 pts had SD, 1 pt PD and 4 pts are not yet evaluable. The most common Grade 3 or 4 AEs were febrile neutropenia, urinary tract infection and confusion. No treatment related deaths were noted. Conclusions: The combination of docetaxel in combination with avelumab is safe and the preliminary data showed promising efficacy, further data to be presented at the meeting. Clinical trial information: NCT03575013.

469 Background: Bacillus Calmette-Guerin (BCG) is the standard of care for patients with new non-muscle invasive bladder cancer (NMIBC) after transurethral tumor resection. While BCG has been compared to single agent intravesical chemotherapy as first-line therapy, few studies exist comparing BCG to sequential intravesical chemotherapy regimens. The objective of this work was to determine the efficacy of sequential intravesical gemcitabine and docetaxel (Gem/Doce) in BCG naïve patients with NMIBC. Methods: Patients without prior BCG exposure who underwent Gem/Doce intravesical treatments were retrospectively identified. These patients had been treated with 6 weekly instillations of gemcitabine (1 gram of gemcitabine in 50 ml of sterile water) followed immediately by docetaxel (37.5 mg of docetaxel in 50 mL of saline). Patients without recurrence then underwent maintenance therapy with monthly instillations for two years. Treatment success was defined as no bladder cancer recurrence and no cystectomy. Survival analysis was performed using the Kaplan Meier method. Results: 30 patients were treated with a median follow-up of 18 months. Eighty percent (n=24) of patients had high risk disease. Median age was 78 years old. The most common indications for Gem/Doce therapy were “advanced age/frailty” (n=15), “immunosuppression” (n=4), and “BCG Shortage” (n=4). Treatment success was 96% at 3 months, 89% at 1 year, and 89% at 2 years. No patients progressed or required cystectomy. Treatments were generally well tolerated, with only one patient unable to finish induction and two patients declining maintenance. Side-effects included urinary urgency/frequency (30%), dysuria (26%), and hematuria (23%). A need for dose reduction or delay was uncommon (16%). The all-cause mortality rate was 3.5% at 1 year, and 16.5% at 2 years. Neither bladder cancer nor the treatments were the cause of any of the deaths. Conclusions: Sequential intravesical gemcitabine and docetaxel is an effective treatment for BCG naïve NIMBC. Treatments are generally well tolerated even in a frail and comorbid patient population. Further evaluation of this combination therapy for BCG naïve disease is warranted.

660 Background: The overexpression of hypoxia induced factor 1a/2a in ccRCC leads to up-regulation of vascular endothelial growth factor (VEGF) that results in increased angiogenesis, tumor metastasis, and treatment resistance. Using several preclinical xenograft models, it has been demonstrated that therapeutic doses of the selenium-containing molecules, seleno-L-methionine (SLM) and methylselenocysteine (MSC) caused enhanced degradation of HIF1α/2α, down-regulation of oncogenic miRNA-210 and 155, up-regulation tumor suppressor miRNA-664 and LET-7b, and stabilization of tumor vasculature, yielding higher tumor drug uptake and protection from toxic side effects when combined with chemotherapeutic and VEGF-targeted agents. Methods: This is a phase I (3+3 design) dose finding trial of SLM (2500, 3000 or 4000 µg) given orally twice daily for 14 days, followed by once a day in combination with standard dose axitinib to patients with metastatic RCC. Primary endpoint is safety. Secondary endpoint is efficacy including overall response rate (ORR), progression free survival (PFS) and overall survival (OS). Results: To date, 12 evaluable patients (pts) with metastatic RCC who progressed on one or more prior lines of treatment were enrolled. The first 3 pts were treated at 4000 µg, the second and third 3 pts were treated at 2500 and 3000 µg respectively. Additional 3 pts were added to 4000 µg. No dose limiting toxicity (DLT) was seen. Most common AEs included fatigue, diarrhea, hypertension, nausea, anorexia, cough, proteinuria and weight loss. Of the 4000 µg cohort, 2 pts achieved CR with ongoing responses at 31 and 29 months, 1 pt had PR for 24 months and 1 had PD at 3 months, 2 pts are not assessed yet. Of the 2500 µg cohort, 1 pt with ongoing PR for 21 months, 1 pt had stable disease for 6 months, and 1 pt had PD at 2 months. The 3000 µg cohort, one pt has ongoing PR for 12 months; another pt had PR lasting 10 months, the 3rd pt had SD for 4 months. Conclusions: High dose SLM is safe in combination with axitinib, with promising efficacy. Further data including biomarkers will be presented at the meeting. Clinical trial information: NCT02535533.

630 Background: The overexpression of hypoxia induced factor (HIF) 1a/2a in ccRCC leads to up-regulation of vascular endothelial growth factor (VEGF) that results in increased angiogenesis, tumor metastasis, and treatment resistance. Using several preclinical xenograft models, it has been demonstrated that therapeutic doses and schedules of the selenium-containing molecules, seleno-L-methionine (SLM) and methylselenocysteine (MSC) caused enhanced degradation of HIF1α/2α, down-regulation of oncogenic miRNA-210 and 155, up-regulation tumor suppressor miRNA-664 and LET-7b, and stabilization of tumor vasculature, yielding higher tumor drug uptake and protection from toxic side effects when combined with chemotherapeutic and VEGF-targeted agents. Methods: This is a phase I (3+3 design) dose finding trial of SLM (2500, 3000 or 4000 µg) given orally twice daily for 14 days, followed by once a day in combination with the standard dose of axitinib to patients with metastatic RCC. Primary endpoint is safety, secondary endpoint is efficacy including overall response rate (ORR), progression free survival (PFS) and overall survival (OS). Results: To date, 9 patients with metastatic RCC; who failed one or more prior lines of treatment; are enrolled. The first 3 patients were treated at 4000 µg, the second and third 3 patients were treated at 2500 and 3000 µg respectively. No dose limiting toxicity (DLT) is encountered. Six patients are evaluable to date. Of the 4000 µg cohort, 2 patients achieved complete remission (CR) at 18 and 20 months, 1 patient with partial response (PR) at 19 month. Of the 2500 µg cohort, one patient achieved PR at 9 months, 1 patient had stable disease for 9 months before progression, and 1 patient had disease progression at 4 months. The 3000 µg cohort is too early to evaluate for efficacy. Of interest the 4000μg SLM dose yielded a plasma selenium concentration of 40-50μM which is comparable with SLM dose determined synergistic with anti-cancer drugs in preclinical models. Conclusions: High dose SLM is safe in combination with axitinib, with promising efficacy, further data to be presented at the meeting. Clinical trial information: NCT02535533.

e16132 Background: AdPSA is an investigational replication-deficient adenovirus-based PSA vaccine. A prior phase I trial in patients with metastatic castrate-resistant prostate cancer (CRPC) showed...

4594 Background: The survival benefit with neoadjuvant chemotherapy for bladder cancer was established in 2003. However, adoption of this paradigm in clinical practice has been slow. We explored the use of neoadjuvant chemotherapy and identified predictors of its use in a contemporary cohort in the Veterans Health Administration (VA). Methods: Using the national VA Clinical Cancer Registry, all patients diagnosed with clinical stage T2-4, N0 or Nx, M0 bladder cancer from 1997 to 2007 were stratified into surgically (radical cystectomy [RC], n=1,211) and nonsurgically managed groups (n=2,125). Receipt of neoadjuvant chemotherapy was defined as chemotherapy treatment up to 6 months before RC as well as initial treatment only with chemotherapy (without subsequent surgery or radiation) in the nonsurgical group. Temporal trends in neoadjuvant chemotherapy use were evaluated with a chi square test. Predictors of neoadjuvant chemotherapy were examined using a multivariable logistic regression model incorporating demographic, socioeconomic, comorbid, pathologic and hospital factors. Results: 6.3% and 8.3% of patients received neoadjuvant chemotherapy in the surgical and non-surgical group, respectively. Analysis of temporal trends in chemotherapy use demonstrated an increase in neoadjuvant chemotherapy use over time (p

113 Background: Multiple definitions of high risk prostate cancer exist. Studies have primarily correlated these definitions with biochemical recurrence and not with survival. We applied six previously described high risk definitions to men treated with radical prostatectomy and evaluated their ability to predict survival outcomes in a multi-institutional cohort. Methods: The study population included 6477 men treated with radical prostatectomy between 1995 and 2005 and followed for a median of 67 months. The six high risk definitions were 1) preoperative PSA≥20ng/ml, 2) biopsy Gleason score 8-10, 3) clinical stage≥T2c, 4) clinical stage T3, 5) D’Amico definition, or 6) National Comprehensive Cancer Network definition. Survival was evaluated with the Kaplan-Meier method to generate unadjusted prostate cancer survival estimates. To control for the competing risks of age and comorbidity, multivariable Cox proportional hazard regression models were used to estimate the hazard ratio for prostate cancer specific mortality (PCSM) and overall mortality (OM) in high risk patients compared to low/intermediate risk. Results: High risk patients comprised between 0.7% (cT3) and 8.2% (D’Amico) of the study population. The 10-year Kaplan Meier prostate cancer survival estimates varied from 89.7% for PSA≥20 to 69.7% for cT3. On multivariable analysis controlling for age and comorbidity, high risk prostate cancer (of all definitions) had an increased risk of PCSM compared to low/intermediate risk with a hazard ratio (HR) ranging from 4.38 for PSA≥20 to 19.97 for cT3 (all p Conclusions: In a contemporary cohort of men with high risk prostate cancer treated with radical prostatectomy, the majority of men experienced long term prostate cancer survival. However, heterogeneity in survival outcomes existed based on the definition of high risk used. Clinical stage T3 and high Gleason score were most strongly associated with PCSM and OM.

73 Background: Analysis from population-based cancer registry data has suggested that being married is associated with improved survival in men with prostate cancer. However, a limitation of such analysis is the inability to control for PSA or medical comorbidity which may differ by marital status. We investigated the association between marital status and both prostate cancer specific mortality (PCSM) and overall mortality (OM) in men treated with radical prostatectomy. Methods: The study population included 3596 men treated with radical prostatectomy at a single institution between 1994 and 2004 and followed for a median of 72 months. Disease specific factors (PSA, clinical stage, and biopsy Gleason grade), comorbidity (validated ACE-27 comorbidity index), ethnicity, age, and marital status at time of treatment were retrieved from an institutional cancer registry. Differences between marital status groups were evaluated by Chi square or ANOVA. Multivariable Cox proportional hazard regression models were used to estimate the hazard ratio (HR) of PCSM and OM by marital status. Results: 86.9% of men were married, 5.3% divorced, 2.4% widowed, and 5.5% never married. Marital status was associated with differences in PSA (p Conclusions: Never married men had an increased risk of PCSM and OM. Factors associated with social isolation or unhealthy behaviors may have a detrimental effect on survival after prostatectomy. [Table: see text]