Anti-cancer drug usage analysis among Korean patients with colorectal cancer

Combination chemotherapy has long been central to the management of colorectal cancer, and treatment patterns have evolved in response to emerging clinical evidence, changing guidelines, and the availability or withdrawal of specific agents. This study aims to characterize changes in medication utilization over time by providing a descriptive analysis of temporal changes in anticancer drug use among Korean colorectal cancer patients treated at the National Cancer Center (NCC) of Korea. Two patient cohorts were examined: individuals treated between 2000-2004 and those treated between 2010-2020. Sixteen anticancer agents administered to ≥10 patients in both cohorts were included. A total of 1,188 patients from the 2000-2004 cohort and 1,043 patients from the 2010-2020 cohort were analyzed using Stata/BE 18.0. In the 2000-2004 cohort, monotherapy was the most predominant treatment approach (55.89%), followed by two-drug combination therapy (17.68%). Among monotherapies, 5-fluorouracil (5-FU) was most frequently used (45.96%). The most common two-drug regimen during this period was capecitabine plus 5-FU (4.88%). By 2010-2020, treatment patterns shifted as two-drug combination chemotherapy became more common than monotherapy (38.73% vs. 32.02%). The 5-FU plus oxaliplatin combination emerged as the most frequently used regimen (25.98%). Capecitabine was the most common regimen for monotherapy (21%). Although the use of capecitabine monotherapy increased in 2010-2020 compared to 2000-2004 (21% vs. 5.56%), the difference in overall capecitabine usage was not statistically significant (p = 0.872), likely because capecitabine had frequently been used in combination regimens in earlier years. In contrast, use of 5-FU significantly declined (p < 0.001), while use of oxaliplatin and bevacizumab markedly increased (both p < 0.001). Meanwhile, tegafur/uracil and megestrol usage decreased significantly (both p < 0.001). This descriptive analysis highlights shifts in chemotherapy use among colorectal cancer patients treated at the NCC of Korea across two distinct periods. The earlier cohort (2000-2004) was characterized by predominant use of 5-FU-based monotherapy, whereas the later cohort (2010-2020) showed a marked transition toward two-drug combinations. These patterns mirror global changes in anticancer therapy drug usage. Further analyses should link treatment patterns to clinical outcomes, including evaluations of overall survival (OS) and disease-free survival (DFS), clarification of treatment lines, and resolution of overlapping-prescription or regimen-coding issues. This study was approved by the Institutional Review Board of the NCC (NCC2025-0115).