BACKGROUND/OBJECTIVES: We investigated the association between chronic rhinosinusitis (CRS) and cancer risk in an adult Korean population. METHODS: This retrospective cohort study used data from the Korean National Health Insurance Service database. To ensure comparability between the groups, adjustments were made for potential confounding factors, including sex, age, residence, household income, diabetes, hypertension, and chronic kidney disease. The primary endpoint was the presence of newly diagnosed cancer. RESULTS: Among 1,337,120 individuals in the nationally representative cohort database, 10,567 patients with CRS were identified and matched with 42,268 control subjects without CRS. Patients with CRS had a significantly higher risk of overall cancer events than controls. The adjusted hazard ratio (HR) for cancer in the CRS group was 1.16 (95% confidence interval [CI]: 1.05-1.28). Notably, female patients with CRS had an elevated risk of incident cancer events. Furthermore, patients with CRS without nasal polyps exhibited a significantly increased risk of cancer, whereas those with CRS with nasal polyps did not show a similar association. CONCLUSIONS: These findings underscore the need for physicians to carefully monitor patients with CRS for potential cancer progression and develop appropriate therapeutic strategies to mitigate the impact of this condition.