Shifting Cancer Landscapes in Korea: Divergent Incidence Trajectories, Sex-Specific Burdens, and Projected Case Counts for 24 Major Cancer Types from 1999 to 2023, with Forecasts to 2030.

BACKGROUND/OBJECTIVES: Korea has experienced rapid and heterogeneous shifts in cancer epidemiology since 1999. We aimed to characterize divergent incidence trajectories across the 24 major cancer types, quantify sex-specific burdens, and project case counts through 2030. METHODS: Annual incidence data-including new case counts and age-standardized incidence rates (ASIRs) per 100,000 (2020 Korean standard population) stratified by sex-were extracted from the KCCR via the Korean Statistical Information Service (KOSIS) for 1999-2023. Annual percent change (APC) was estimated by log-linear regression with 95% confidence intervals (CIs). Holt-Winters damped exponential smoothing generated 2024-2030 projections with 95% prediction intervals (PIs). Changes in case ascertainment and coding over the study period were considered in interpretation. RESULTS: Total incidence increased from 101,854 (1999) to 288,613 cases (2023), a 183.4% increase. Overall ASIR rose from 402.7 to 522.9 per 100,000. Of the 24 cancer types, 15 showed statistically significant increasing ASIR trends, 6 showed significant decreasing trends, and 3 showed no significant change. The highest-APC cancers were thyroid (+7.56%), prostate (+6.98%), testis (+5.39%), breast (+5.03%), and corpus uteri (+5.03%; all p < 0.001). The largest significant declines occurred in cervix uteri (-3.81%), larynx (-3.18%), liver (-2.90%), and stomach (-2.20%; all p < 0.001). Female ASIR increased from 294.7 to 488.9 per 100,000 (+65.9%); male ASIR increased from 573.3 to 587.0 per 100,000 (+2.4%). Total cancer incidence is projected to reach 307,091 (95% PI: 281,200-332,983) in 2026 and 330,213 (95% PI: 290,663-369,763) by 2030, with the steepest projected relative growth for prostate (+48.9%), kidney (+33.7%), and breast (+31.3%) cancers. CONCLUSIONS: Korean cancer epidemiology is undergoing a pronounced transition from infection-related toward metabolic, hormonal, and aging-related malignancies, with a marked and widening sex-specific divergence. Cancer-type-resolved projections through 2030 provide an evidence base for strategic capacity planning in Korean oncology.