Relapse detection in the Danish surveillance program of patients with clinical stage I seminoma: a nationwide study.

Background and purpose: Active surveillance is a recommended management strategy for patients with clinical stage I (CSI) seminoma. This study aims to identify patterns of relapse detection methods in an unselected population-based cohort of CSI patients and provide evidence for a risk-adapted follow-up program.

Patients/materials and methods: A total of 924 patients with CSI seminoma were identified in the prospective Danish Testicular Cancer database. Retrospectively collected clinical data were used for descriptive analyses of patterns in detection methods. Additionally, we explored a risk-adapted surveillance approach based on recently identified risk factors for relapse, classifying patients into low- and non-low-risk groups.

Results: At 60 months, the 5-year cumulative relapse risk was 16%, with 146 relapses during surveillance. Relapses were detected by imaging alone in 71% of cases, imaging combined with elevated serum tumor markers (STMs) in 18%, isolated elevation of STMs in 8%, and by self-referral due to symptoms in 3%. No relapses were detected by abnormal findings at a physical examination. In total, 134 (92%) relapses were localized to retroperitoneal lymph nodes, primarily without additional spread. The 5-year relapse risk in patients with low risk of relapse was 9% compared to 28% in patients in the non-low-risk group.

Interpretation: This study highlights that the surveillance program can detect relapses at an early stage. Reduction of visits and omission of routine physical examinations can safely be considered for patients with a low risk of relapse, while further research is needed to optimize follow-up and treatment for patients at higher risk of relapse.