Longitudinal Analysis of Testicular Cancer Patient Volume and Co-Occurring Urological Conditions Using the Health...

Background/Objectives: Testicular cancer (TC) is the most common solid malignancy in young males globally, yet population-level longitudinal data characterizing claims-based patient volume trends and co-occurring urological condition burden in South Korea remain limited. This study aimed to describe national trends in TC patient volume from 2020 to 2024, quantify exploratory associations with co-occurring urological and oncological conditions using aggregate annual counts, and generate exploratory 2026-2028 forecasts using validated statistical methods. Methods: We conducted a retrospective longitudinal analysis of administrative claims data from the Health Insurance Review and Assessment (HIRA) database of South Korea (2020-2024). Ten disease categories were analyzed: testicular cancer, bladder cancer, kidney cancer, prostate cancer, benign prostatic hyperplasia (BPH), chronic kidney disease (CKD), cystitis, neurogenic bladder, pyelonephritis, and carcinoma in situ. Annual patient counts, inpatient/outpatient utilization, and healthcare costs were extracted. Pearson and Spearman correlations were computed between TC and co-occurring condition volumes. Forecasting for 2026-2028 used a three-method ensemble: ARIMA(1,1,0), linear regression with 95% prediction intervals, and Holt-Winters exponential smoothing (weights: 0.35, 0.35, 0.30, respectively). The study was approved by the Institutional Review Board of Chungnam National University (IRB No. 202601-SB-014-01). All data were fully de-identified; informed consent was waived. Results: TC patient volume increased from 2309 in 2020 to 2992 in 2024 (compound annual growth rate [CAGR]: 6.69%). Exploratory ensemble forecasts projected 3287 (95% prediction interval [PI]: 2856-3540), 3767 (95% PI: 2962-3749), and 4531 (95% PI: 3066-3962) patients in 2026, 2027, and 2028, respectively, under a continued linear-trend assumption. TC patient volume showed strong positive exploratory correlations with CKD (r = 0.946, p < 0.05), prostate cancer (r = 0.945), kidney cancer (r = 0.932), BPH (r = 0.932), carcinoma in situ (r = 0.937), and bladder cancer (r = 0.928); given n = 5 annual observations, these reflect parallel secular trends and must not be interpreted causally. Nine of ten analyzed conditions demonstrated increasing trends; pyelonephritis showed a negative CAGR (-1.37%). Conclusions: TC patient volume in South Korea increased substantially over 2020-2024, with exploratory forecasts projecting continued growth through 2028. Parallel upward trends in co-occurring urological and oncological conditions are consistent with shared secular drivers including population ageing and improved detection, though individual-level causal inference is not possible from aggregate claims data. These findings support claims-based trend monitoring, urological oncology resource planning, and hypothesis generation for future individual-level studies.