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5088 Background: PSCC patients (pts) with palpable inguinal lymph node (ILN) disease have a poor overall survival (OS). Multimodal perioperative treatments are usually offered despite the lack of clinically meaningful efficacy. Pending the availability of novel effective systemic therapy, the optimization of conventional treatments in better selected pts is needed. Methods: Within an international, multicenter database of 924 PSCC pts who received ILN dissection from USA, Europe, Brazil and China, 494 had information on HPV, and 52 (10.5%) had HPV+ PSCC, predominantly assessed with immunohistochemistry (53%). Multivariable logistic regression analyses evaluated the association between pt factors and HPV status. Multivariable Cox analyses (MVA) assessed predictors of overall mortality (OM), including HPV status, pathologically-involved ILN ratio (ILNR), extranodal extension, margin status, vascular invasion (VI), perioperative RT (pRT) and perioperative chemotherapy (pCT). Comparisons between HPV status and ILNR were performed using interaction tests. Kaplan-Meier method was used to define the OS benefit related in HPV-stratified sub-groups. Results: Median age at diagnosis was 58yrs. Overall, pCT and pRT were used in 227 (46%) and 50 (10%) pts. The median follow-up was 62 months. Neither clinical factors nor country were associated with HPV status. On MVA, ILNR (HR:1.01, p = 0.01) and extranodal extension (HR: 1.5, p = 0.02) were statistically significantly associated with OM, but HPV was not (p = 0.2). However, in the subgroup of pts who received pRT, HPV status was associated with favorable OM (HR: 0.11, 95%CI: 0.03-0.5, p = 0.004) together with negative VI (p = 0.03), and the use of adjuvant CT (p = 0.04). A significant interaction was found on OM between HPV+ status and increasing ILNR, with a cutoff at 50% (p = 0.05). Results are limited by their retrospective nature and small numbers in each subgroup. Conclusions: In the largest available dataset of ILND for PSCC, we observed that pRT seemed to be more effective in the subgroup of HPV+ PSCC. These results should be considered as hypothesis-generating and may inspire both the future prospective trials or the ongoing InPACT study.

5585 Background: PSCC is a rare tumor and the administration of guidelines-based therapies is still problematic in real-world practice. Survival outcomes remain suboptimal in patients (pts) with ILN involvement. Multinational analyses of real-world patterns are needed. Methods: Within an international, multicenter database of 965 PSCC pts who received ILND from 1980-2019, 630 had complete information for the variables of interest, from USA (N=81), Europe (EU, N=355), South America (SA, N=90), and China (Ch, N=104). Descriptive analyses according to geographical and ethnicity/race distribution were made. Comparisons of outcomes were made with Kaplan-Meier analyses and corresponding logrank tests. Results: Median age at diagnosis was 59 yrs, with no differences worldwide and according to ethnicity/race. Pts from SA presented with more advanced cT-stage (cT3-4: 26.7% vs. 17.3% USA vs. 7.6% EU) while EU pts presented with more advanced cN-stage (cN3: 14.9% vs. 11% USA vs. 7.8% SA vs. 5.8% Ch) as well as pathological (p)N-stage: pN3 pts were 53% in EU, 33.3% in USA, 20% in SA, and 18.3% in Ch. Perioperative chemotherapy (pCT) was more frequently administered in EU (53.8%) vs. USA (34.6%) SA (5.6%) Ch (7.7%). cT-stage was more frequently advanced in black pts (cT3-4: 33.3% vs. 12% Caucasian, 6.2% Hispanic/latino, 0% Asian) and the same was for cN-stage (cN3: 25% in black, 13% in Caucasian, 6.2% in Hispanic/latino, 6% in Asian). Conversely, pN3 pts were more frequently Caucasian (45.6%) vs. black (25%), Hispanic/latino (19%), and Asian (18%). pCT was more frequently administered in Caucasian pts (45%) vs. black (8.3%), Hispanic/latino (0), and Asian (8%). No significant differences in overall survival (OS) were observed according to geographical region or ethnicity/race, in the total pts and in the subgroups according to cT, cN, pN-stages and pCT. Median OS after pCT and ILND was 95 months. Bilateral ILN involvement was equally observed regardless of geographical region and ethnicity/race. In the total population, pCT significantly prolonged OS in pts with bilateral ILN (p=0.04), but not in pts with pelvic LN. Conclusions: Treatment patterns for PSCC undergoing ILND remain heterogeneous worldwide, and adherence to guidelines is seemingly poor. However, long-term outcomes with pCT remain uniformly suboptimal with

2 Background: PSCC patients (pts) with palpable inguinal lymph node (ILN) disease have a poor overall survival (OS). For them, use of neoadjuvant chemotherapy (NAC) is recommended in guidelines, but limited data are available to inform pt selection. We aim to identify predictors of poor OS in clinically ILN-positive (ILN+) pts to define the optimal candidates for NAC. Methods: Within an international, multicenter database of 924 PSCC pts, we identified 334 ILN+ pts with available data. ILN involvement was defined either with the presence of palpable ILN disease or based on preoperative CT-scan. FDG-PET/CT-scan was performed based on clinical judgment of the treating physician. Univariable and multivariable analyses (MVA) assessed predictors of overall mortality (OM). A regression-tree method for censored data was used to generate a risk stratification tool for prediction of 24m OM after diagnosis of ILN+ PSCC. Kaplan-Meier method was used to define the OS benefit related to the use of NAC according to the regression-tree stratified sub-groups. Results: Median age at diagnosis was 58yrs, and 105 (31.4%) had ECOG≥1. Of all, 120 (35.9%), 152 (45.5%), and 62 (18.6%) harbored cN1, cN2, and cN3 disease. Additionally, 152 (45.5%) and 117 (35%) had monolateral vs bilateral clinical ILN involvement. FDG-PET/CT was adopted in 42 (12.2%) pts, and 16 (4.8%) had pelvic LN uptake. Median OS was 107m, with 24m OS = 66%. At MVA, cN2 (HR: 2.28, p=0.006), cN3 (HR: 2.15, p=0.02), PET/CT scan-detected pelvic and ILN involvement (HR: 2.57, p=0.007) were independently associated with higher OM, whether bilateral clinical ILN+ was only univariably significant (HR: 1.56, p=0.02). At regression-tree analysis (AUC 70%), pts with cN3 and cN2 with PET/CT-detected pelvic and ILN involvement had the higher risk of 24m OM (>54%). NAC was associated with improved 24m OS rates (54 vs. 33%) only in this pt subgroup (p=0.002). Conclusions: NAC improves OS in pts with cN3 or cN2 and pelvic FDG-PET/CT scan-detected disease. Our regression-tree may serve to screen ILN+ pts, to identify the optimal NAC candidates before radical treatments.

222 Background: Penile cancer is a rare malignancy affecting approximately 400 men per year in the United Kingdom. There are relatively limited data regarding the role of chemotherapy, although it may be considered in the adjuvant setting for high-risk disease and for palliation of metastatic disease. Methods: Patients treated with chemotherapy between June 2002 and March 2010 were identified from our prospectively maintained institutional database. Regimens were recorded and toxicity documented according to the Common Toxicity Criteria version 4.0. Response was assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 until 2009 and then version 1.1. Results: Twenty patients received chemotherapy either for adjuvant treatment (n=6) or for metastatic disease (n=14). Median age was 59 (range 33-80). Different regimens were used over the time period. In the adjuvant setting 4-6 cycles of chemotherapy were planned and all patients received cisplatin in combination with 5-FU or capecitabine. Five (83%) completed planned treatment with no grade 3 or 4 toxicities. One patient stopped after 2 cycles due to deteriorating renal function. Patients remained disease free at up to 22 months follow-up. In the metastatic setting, 10 patients received cisplatin and capecitabine, 1 cisplatin and 5-FU and 1 carboplatin and capecitabine. Of these 12 patients, 2 (17%) had partial response as their best response, 4 (33%) had stable disease (SD) and 6 (50%) had progressive disease (PD). Three patients (25%) experienced pulmonary embolism, 1 of whom died. Two (17%) developed grade 3 neutropenia. One patient received carboplatin, methotrexate and bleomycin with PD after 3 cycles and developed grade 3 neutropenia, stomatitis, and diarrhea. One patient received 3 cycles of paclitaxel, ifosfamide, and cisplatin with SD and no grade 3 or 4 toxicities. Conclusions: Combination chemotherapy can be delivered with acceptable toxicity in the adjuvant setting. In the metastatic setting response rates were disappointing and treatments were associated with greater toxicity. New treatments are urgently required to improve outcomes in this difficult malignancy. [Table: see text]