Masterson, Timothy A.

605 Background: Patients with stage I testicular cancer (TCa) have excellent survival, and surveillance after orchiectomy is often preferred. Limited data exist on survivorship outcomes of surveillance versus adjuvant therapy. We compared systemic health outcomes between patients managed with surveillance and those treated with upfront therapy. Methods: Claims data from the OptumLabs Data Warehouse (2007–2022) identified stage I TCa patients managed with surveillance, chemotherapy, or radiation. Adjuvant therapy was defined as chemotherapy or radiation within 4 months of diagnosis with no further therapy. Chemotherapy codes were required within 42 days to ensure multiple cycles were not given. Propensity score–matched cohorts were created using logistic regression. A 3-year analysis evaluated new diagnoses of cardiopulmonary complications, metabolic syndrome, men’s health, psychological, and miscellaneous systemic conditions. Outcomes were stratified by treatment group. Chi-square tests and Cox regression analyses compared survivorship outcomes between adjuvant therapy and surveillance. Results: Eight-hundred forty-two patients had 3 years of coverage: 531 surveillance, 159 chemotherapy, and 152 radiation. No significant differences were found in cardiopulmonary, metabolic, psychological, or other systemic outcomes between therapy and surveillance (Table 1). Men’s health diagnoses were more frequent with chemotherapy (35.2% vs 23.9%, p=0.027) compared to surveillance. However, Cox regression showed no significant time-to-event differences on time-to-event analysis between groups. Conclusions: Adjuvant chemotherapy may be associated with higher rates of men’s health complications (infertility, erectile dysfunction, hypogonadism), but over time the risk is not significantly different than surveillance. Propensity-score matched survivorship outcomes: A) surveillance vs chemotherapy; B) surveillance vs radiation. A) Surveillance (N=159) Chemotherapy (N=159) p value Cardiopulmonary Complications 0.157 Yes 14 (8.8%) 22 (13.8%) No 145 (91.2%) 137 (86.2%) Men’s Health Complications 0.027 Yes 38 (23.9%) 56 (35.2%) No 121 (76.1%) 103 (64.8%) Metabolic Syndrome Complications 0.631 Yes 53 (33.3%) 49 (30.8%) No 106 (66.7%) 110 (69.2%) Miscellaneous Systemic Disorders 0.879 Yes 25 (15.7%) 26 (16.4%) No 134 (84.3%) 133 (83.6%) Psychological Diagnoses 0.401 Yes 29 (18.2%) 35 (22.0%) No 130 (81.8%) 124 (78.0%) B) Surveillance (N=152) Radiation (N=152) p value Cardiopulmonary Complications 0.682 Yes 12 (7.9%) 14 (9.2%) No 140 (92.1%) 138 (90.8%) Men’s Health Complications 0.630 Yes 51 (33.6%) 55 (36.2%) No 101 (66.4%) 97 (63.8%) Metabolic Syndrome Complications 0.086 Yes 42 (27.6%) 56 (36.8%) No 110 (72.4%) 96 (63.2%) Miscellaneous Systemic Disorders 0.650 Yes 25 (16.4%) 28 (18.4%) No 127 (83.6%) 124 (81.6%) Psychological Diagnoses 0.650 Yes 28 (18.4%) 25 (16.4%) No 124 (81.6%) 127 (83.6%)

PURPOSE The long-term toxicities of chemotherapy and radiotherapy can represent a significant burden to testicular cancer survivors. Retroperitoneal lymph node dissection (RPLND) is an established treatment for testicular germ cell tumors with minimal late morbidity although little data exist on its efficacy in early metastatic seminoma. Surgery in early metastatic seminoma is a prospective phase II single-arm, multi-institutional trial of RPLND as first-line treatment for testicular seminoma with clinically low-volume retroperitoneal lymphadenopathy. PATIENTS AND METHODS Twelve sites in the United States and Canada prospectively enrolled adult patients with testicular seminoma and isolated retroperitoneal lymphadenopathy (1-3 cm). Open RPLND was performed by certified surgeons with a primary end point of 2-year recurrence-free survival (RFS). Complication rates, pathologic up/downstaging, recurrence patterns, adjuvant therapies, and treatment-free survival were assessed. RESULTS A total of 55 patients were enrolled, with a median (IQR) largest clinical lymph node size of 1.6 cm (1.3-1.9). RPLND pathology demonstrated a median (IQR) largest lymph node size of 2.3 cm (0.9-3.5); nine patients (16%) were pN0, 12 (22%) pN1, 31 (56%) pN2, and 3 (5%) pN3. One patient received adjuvant chemotherapy. With a median (IQR) follow-up of 33 months (12.0-61.6), 12 patients experienced recurrence, with a 2-year RFS of 81% and a recurrence rate of 22%. Of the patients who experienced recurrence, 10 were treated with chemotherapy and two underwent additional surgery. At last follow-up, all patients who experienced a recurrence were disease-free and the 2-year overall survival was 100%. Four patients (7%) experienced short-term complications, and four patients experienced long-term complications including incisional hernia (1) and anejaculation (3). CONCLUSION RPLND is a treatment option for testicular seminoma with clinically low-volume retroperitoneal lymphadenopathy and is associated with low long-term morbidity.

375 Background: Chemotherapy or radiotherapy are standard treatments for stage II seminoma, though they are associated with significant long-term treatment-related toxicities. Retroperitoneal lymph node dissection (RPLND) is an established treatment for testicular germ cell tumors but little data exists on its efficacy as a front-line treatment in early metastatic (stage II) seminoma. This is a single-arm, multi-institutional (NCT02537548), phase II study of retroperitoneal lymph node dissection (RLND) as first-line treatment for testicular seminoma with isolated retroperitoneal disease. Methods: Twelve sites in the United States and Canada prospectively enrolled patients (16 years of age) with testicular seminoma and isolated retroperitoneal lymphadenopathy between 1-3 cm in size. Patients were excluded if they received prior therapy (except orchiectomy) for testicular cancer. Open, modified-template RPLND was performed by qualified surgeons with a primary endpoint of 2-year recurrence-free survival. Data on complication rates (short and long-term), pathologic up/downstaging, recurrence patterns, adjuvant therapies, and treatment-free survival were assessed. Results: A total of 55 patients were enrolled and underwent RPLND. Fourteen patients had initial stage I disease who developed isolated retroperitoneal relapse while 41 patients had clinical stage IIA-B at presentation. With a median follow-up of 24 months (8-52 months), there were a total of 10 recurrences. The overall recurrence rate was 18% with a median time to recurrence of 8 months. Of the recurrences, 8 underwent chemotherapy (6 BEP X 3, 1 EP X 4, 1 carbo/etoposide) and 2 underwent additional surgery. The two-year recurrence free survival was 87% and the overall survival was 100%. There were 7 (13%) patients who experienced short-term complications within 1 year of RPLND. Of these, 5 (9%) were classified as Clavien Dindo I-II and 2 (3.6%) were classified as Clavien Dindo III. No patients have reported long-term complications. Conclusions: This trial establishes RPLND as a therapeutic option as a first-line treatment in early metastatic seminoma. The surgery offers cancer control rates similar to those seen in non-seminomatous germ cell tumors. Clinical trial information: NCT02537548.