Pandemic-Era Stage Migration, Registry-Recorded Primary-Site Surgery, and Survival in Early-Onset Testicular Germ Cell Tumors: A SEER Population-Based Study

Background: This study evaluated temporal changes in stage distribution, registry-recorded primary-site surgery, survival outcomes, and exploratory short-term mortality prediction among patients with early-onset testicular germ cell tumors, defined in this study as tumors diagnosed in patients aged 15–49 years, across the study periods. Materials and Methods: This retrospective cohort study used Incidence-SEER Research Data, 17 Registries, November 2025 Submission. Male patients aged 15–49 years diagnosed with malignant testicular germ cell tumors between 2018 and 2023 were included. Diagnosis periods were categorized as the pre-COVID-19 period (2018–2019), COVID-19 period (2020–2021), and 2022–2023 period. Logistic Regression was used to assess factors associated with regional or distant-stage disease. Overall survival was evaluated using Cox regression, while testicular cancer-specific death was additionally evaluated using Aalen–Johansen cumulative incidence estimates and Fine–Gray competing-risk regression. Follow-up was also restricted to 12 months in sensitivity analyses. Machine learning models were developed as an exploratory secondary analysis of 12-month all-cause mortality. Results: A total of 13,303 patients were included. Among patients with known stage, regional or distant-stage disease increased from 31.2% before the pandemic to 33.5% during the COVID-19 period and 34.4% during the 2022–2023 period. In adjusted analysis, COVID-19 (OR = 1.11, 95% CI: 1.02–1.22) and diagnoses during the 2022–2023 period (OR = 1.16, 95% CI: 1.06–1.28) were associated with higher odds of regional or distant-stage disease. In full follow-up analyses, diagnosis during the 2022–2023 period was associated with higher all-cause mortality (HR = 1.29, 95% CI: 1.01–1.65) and testicular cancer-specific death in both cause-specific Cox (HR = 1.49, 95% CI: 1.12–2.00) and Fine–Gray models (sHR = 1.45, 95% CI: 1.09–1.93). In 12-month analyses, the overall survival association was attenuated, whereas the association with testicular cancer-specific death remained significant in the Fine–Gray model (sHR = 1.46, 95% CI: 1.03–2.07). Conclusions: Early-onset testicular germ cell tumors diagnosed during the COVID-19 period and in 2022–2023 showed a modest shift toward regional or distant-stage presentation, while diagnosis in 2022–2023 was associated with higher testicular cancer-specific mortality in competing-risk analyses.