OBJECTIVES:To evaluate safety and early and long-term efficacy of CO2 laser conservative treatments for nonulcerative squamous cell carcinoma (SCC) of the penis. MATERIAL AND METHODS:Within our institutional database (2002-2022, included), we identified 122 consecutive cT1-2 cN0 cM0 patients with penile SCC who underwent conservative CO2 laser treatments. Histologically confirmed local relapses were recorded. Local relapses were classified as early recurrences when occurring <2 years and as late new tumor recurrences when occurring >2 years after first laser treatment. Predictors of disease relapse were analyzed with univariable and multivariable Cox regression models (MCRMs). RESULTS:Median follow-up was 36 months [Interquartile range (IQR) 21-73 months]. Median age was 62 years (IQR: 51-69 years). Median largest lesion size was 10 mm (IQR 5-15 mm). 62 patients had penile intraepithelial neoplasia (PeIN) (51.6%), 30 had pT1 m (24.6%), 28 had pT1 (23%) and 1 had pT2 (0.8%), 2 patients were classified as pTx. In case of invasive lesions, tumor Grade was G1 in 37 (60.7%), G2 in 20 (32.8%), G3 in 4 (6.5%). Early and late recurrences occurred in 28 (22%) and in 21 patients (18%), respectively. Proportion of penis preservation was 93.4% and 92.6% at 2 and 5 years. pT1 stage [Hazard Ratio (HR) 13, Confidence Interval (CI) 1.4-73, p-value 0.02] and flat lesions (HR 7.9, CI 1.06-59, 0.04) achieved independent predictor status for late recurrences. No cancer related deaths were recorded after a median follow-up of 36 months. CONCLUSIONS:As far as we know, this is the largest cohort of patients with penile cT1-T2 SCC who underwent conservative CO2 laser treatment. The vast majority (92%) of these patients preserved their organ at 5 years. Some factors can be of use in preventing or anticipating late recurrences.

Primitive Retroperitoneal Germinal Cell Tumors (pR-GCT) corresponds to the clinical case of retroperitoneal ascertained GCT without evidence of primary testicular tumor and accounts for up to 40 % of extragonadal GCTs. An occult primary testicular tumor is often missed at diagnosis. Treatment modalities and outcomes have not been specifically addressed, preventing robust recommendations. We performed an international call to assess prognosis of treatment outcomes of these pts. Clinical, pathological and treatment data pts with pR-GCT between April 1988 and January 2022 were retrospectively collected across four referral centers. Kaplan Meier methods, univariable and multivariable Cox regression models (MCRMs) were used. Ninety-nine pts (median age 37 years - IQR: 29-45) were collected. Ninety-three (94%) had histological diagnosis by biopsy or primary retroperitoneal lymph-node dissection: 60 (62.5%) had non-seminomatous (pR-NSGCTs) and 33 (34.4%) had seminomatous (pR-SGCTs). IGCCCG prognostic allocation was possible in 91 pts: 34 (35.8%) were good, 23 (24.2%) intermediate and 34 (35.8%) poor-risk, respectively. All pts underwent cisplatin-based chemotherapy, usually BEP (94.9%). After chemotherapy, 25 (25.3%) pts underwent orchiectomy: viable tumor was present in 8 (32%), burn-out lesions in 6 (24%) and no lesion in 11 (44%). After a median FUP of 45 m (IQR:15-90), the 5-yrs OS was 58%, being 85% in case of pR-SGCT and 46% in case of pR-NSGCT. According to IGCCCG classification 5-yrs OS was 83.3% for good, 57% for intermediate, 42% for poor-risk pts, respectively. No difference in term of OS (60% vs 56%, p-value 0.81) was observed between patient who had or not radical orchiectomy. At MCRMs only IGCCCG poor risk category (HR 3.2, CI: 1.18-8.84, p-value 0.02) was independent predictor of a worse OS. Eventually, a significant proportion of patients with pR-GCT had a misclassified primary testicular tumor. 5 years-OS according to IGCCCG-classification is worse than expected. The role of a surgical exploration of the suspected primary tumor remains controversial and the existence of a real category of p-RGCT cannot be excluded.

510 Background: pR-GCT corresponds to the clinical case of retroperitoneal ascertained GCT without radiological evidence of primary testicular tumor and accounts for up to 40% of extragonadal GCTs. An occult primary testicular tumor is often missed at diagnosis. Treatment modalities and outcomes have not been specifically addressed, preventing robust recommendations. We performed an international call to assess prognosis of treatment outcomes of these patients. Methods: Clinical, pathological and treatment data pts with pR-GCT between 04/1988 and 01/2022 were retrospectively collected across 4 referral centers. Kaplan Meier methods, univariable and multivariable Cox regression models (MCRMs) were used. Results: Ninety-nine patients (median age 37 yrs - IQR: 29-45) were collected. Ninety-three (94%) had histological diagnosis by biopsy or primary retroperitoneal lymph-node dissection (RPLND): 60 (62.5%) had non-seminomatous pR-GCTs (pR-NSGCTs) and 33 (34.4%) had seminomatous pR-GCTs (pR-SGCTs). IGCCCG prognostic allocation was possible in 91 pts: 34 (35.8%) were good, 23 (24.2%) intermediate and 34 (35.8%) poor risk, respectively. All pts underwent cisplatin-based chemotherapy, usually BEP regimen (94.9%). After chemotherapy, 25 (25.3%) pts underwent orchiectomy: viable tumor was present in 8 (32%), burn-out lesions in 6 (24%) and no lesion in 11 (44%) cases. After a median follow-up of 45 mos (IQR:15-90), the 5-years OS was 58%, being 85% in case of pR-SGCT and 46% in case of pR-NSGCT. According to IGCCCG classification 5-years OS was 83.3% for good, 57% for intermediate and 42% for poor risk patients, respectively. No difference in term of OS (60% vs 56%, p-value 0.81) was observed between patient who had or not radical orchiectomy. At MCRMs only IGCCCG poor risk category (HR 3.2, CI: 1.18-8.84, p-value 0.02) was independent predictors of a worse OS. Conclusions: Eventually, a significant proportion of pts with a pR-GCT had a misclassified primary testicular tumor. 5 yrs-OS according to IGCCCG classification is worse than expected. The role of a surgical exploration of the suspected primary tumor remains controversial and the existence of a real category of p-GCT cannot be excluded.

Active surveillance (AS) may reduce overtreatment of clinically insignificant prostate cancer (PCa) while keeping the option of definitive therapy for those patients (pts) reclassified over time as higher risk. We performed a prospective clinical trial to evaluate AS: our entire AS cohort was previously reported, we here present clinical outcome for the sub-cohort who received RT at our institution after AS discontinuation. Eligibility criteria included clinical stage ≤T2a, initial PSA<10ng/mL, GPS≤3+3; ≤25% positive cores with a max core length containing PCa≤50% or ≤2 positive cores and PSA density<0.2ng/mL/cc. Active treatment was proposed after GPS upgrading, increase in positive cores, or PSA doubling time<3 yrs. Biochemical failure (BF) was assessed with Kaplan-Meier Nine hundred sixty-three pts have been included in AS. Median follow-up was 5.4 yrs (range 0.2-14). Active treatment free survival @ 5 yrs was 50%. Overall survival @ 10 yrs was 91% (confidence interval (CI) 89-93%), PCa specific mortality and presence of metastasis were 0%. 496/963 (51.5%) pts discontinued AS, 108/496 (22%) received RT at our institution. Details for this cohort are given in table. 96% pts received conventionally fractionated RT (65-80 Gy), 4% had 65 Gy @ 2.6/fr. 60% had irradiation of seminal vesicles and 31% pelvic RT (48-50.4 Gy). 10% pts received neo-adjuvant hormone therapy (HT), 52.7% neoadjuvant+concomitant HT, 2.8% and 32.4% had short and long term adjuvant HT, respectively. 6/108 pts experienced BF (time range 2-7 yrs after RT): 3/6 pts were classified as low risk when exiting AS, 2/6 as intermediate and 1/6 as high risk. Actuarial BF rate @ 5 and 10 yrs was 8% (CI 4.5-11.5%) and 11% (CI 6.4-15.6%), respectively. 2/6 pts (1 intermediate + 1 low risk) registered a clinical failure and received cryoablation as salvage therapy.Abstract SU_35_2340; Table 1Pts characteristics @ AS enrollment (median/range or prevalence)Pts characteristics @ AS discontinuation (median/range or prevalence)Reason for AS discontinuationPSA doubling time: 6.5% increased n° of positive cores: 14% upgrading: 39.3% upgrading AND increased n° of positive cores: 36.4% off protocol: 3.7%age (yrs)70 (45-78)Time of AS discontinuation (mos)15 (4 - 90)PSA (ng/ml)5.6 (2.4- 10)PSA (ng/ml)7 (1 - 25.7)PSA DENSITY (ng/mL/cc)0.12 (0.05-0.88)GPS3+3 21.6% - 3+4 38.2% - 4+3 27.5% - 4+4 9.8% - 4+5 2.9%Clinical stageT1b: 1% - T1c: 91% T2a: 8%N° of positive cores at biopsy3 (1 - 8)GPS3+3: 100%Risk classlow: 18.1% - intermediate: 42.9% - high:39.0%number of positive cores at biopsy1 (1-4) Open table in a new tab AS for favorable risk PCa appears safe in the 10 year time frame: in this cohort we observed 0% PCa mortality/metastasis, with markedly higher risk of dying for other causes. Among pts discontinuing AS and treated at our institution, BF rate was 11% at 10 yrs, which is comparable to BF rates for radical prostatectomy or radiation for favorable-risk pts. Nevertheless, longer follow-up is required to determine true impact of BF rate in this cohort on PCa specific survival.