<b>Background/Objectives:</b> Colorectal cancer (CRC) survivors may face long-term health consequences, yet the relationship between CRC and osteoporosis remains underexplored, particularly in Asia. We conducted a nationwide, retrospective longitudinal cohort study with matched controls using the Korean National Health Insurance Service-National Sample Cohort (2005-2019) to assess whether CRC increases osteoporosis risk or not. <b>Methods:</b> We identified 8733 CRC patients and 34,932 matched controls (1:4 ratio) based on age, sex, income, residence, and index date, excluding individuals with pre-existing osteoporosis. Osteoporosis was defined via ICD-10 codes (M80-M82) plus confirmatory bone imaging claims. Propensity score overlap weighting was applied, and adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using Cox proportional hazards models, with subgroup analyses based on demographic and clinical factors. <b>Results:</b> With up to 16 years of follow-up, osteoporosis incidence rates were 13.80 and 14.30 per 1000 person-years in CRC and control groups, respectively. Adjusted Cox models revealed no significant association between CRC and osteoporosis (HR = 0.95; 95% CI = 0.87-1.04). Subgroup analysis showed a slightly lower risk among CRC survivors aged ≥65 years (adjusted HR = 0.84; 95% CI = 0.75-0.95), though no associations were observed by sex, income, region, or comorbidities. <b>Conclusions:</b> These findings suggest CRC may not be an independent risk factor for osteoporosis in the Korean population. The unexpected age-specific variation warrants cautious interpretation, possibly reflecting competing mortality risks or detection biases.

Although Vietnamese IBD patients had higher baseline clinical and phenotypic severity than their Korean counterparts, no significant differences in short-term outcomes were observed, potentially reflecting the impact of the higher rate and early biologic usage in Vietnamese patients.