Prognostic Factors for Relapse in Patients With Clinical Stage I Testicular Seminoma: A Nationwide, Population-Based Cohort Study.

Purpose: Approximately 20% of patients with clinical stage I seminoma relapse. Tumor size and rete testis invasion have been identified as risk factors for relapse. However, the level of evidence supporting the use of these risk factors in clinical decision making is low. Previous studies have been hampered by selection bias and variable pathology reporting that limit interpretation and generalization of results. We assessed prognostic factors for relapse in an unselected nationwide population-based setting with centralized pathology review.

Methods: Patients with clinical stage I seminoma diagnosed from January 2013 to December 2018 were identified in the prospective Danish Testicular Cancer database. By linkage to the Danish National Pathology Registry, histologic slides from the orchiectomy specimens were retrieved and reviewed blinded to the clinical outcome. Clinical data were obtained from medical records with follow-up until July 2022. The association between prespecified potential clinical and histopathologic prognostic factors and relapse was assessed by the use of Cox regression analysis.

Results: Of 924 patients included, 148 (16%) patients relapsed during a median follow-up of 6.3 years. Invasion of the testicular hilum (rete testis and hilar soft tissue), lymphovascular invasion, and elevated preorchiectomy levels of β-human chorionic gonadotropin and lactate dehydrogenase were independent predictors of relapse. The estimated 5-year risk of relapse ranged from 6% in patients with no risk factors to 62% in patients with all four risk factors with tumor extension into the hilar soft tissue of the testicular hilum. After internal model validation, the prognostic model had an overall concordance statistic of 0.70.

Conclusion: The provided prognostic factors could replace current risk factors in guidelines and be used in future studies investigating risk-adapted follow-up and treatment strategies.