e15107 Background: Surtuins(SIRTs), NAD+-dependent deacetylases, participate in cell metabolism and ageing associated diseases including cancer. The elderly has higher cancer incidence and mortality compared to the young. Many of patients with colorectal cancer are over the age of 80. The role of SIRT 1 and 2 in tumorigenesis remains debated and it has not been reported for the very elderly patients with cancer. We investigated the relationship of clinicopathologic parameters and expression of SIRT1 and 2 in colorectal cancer patients 80 years of age or older and the impact of ageing comparing with the younger patients. Methods: The expression of SIRT1 and 2 were evaluated in colorectal cancer tissues of 101 patients aged ≥80 years and 29 patients aged ≤40 years by immunohistochemistry. And correlations between expression of these proteins and clinicopathological features were analyzed. Results: High expression of SIRT1 was observed in 65/101 (64.4%) elderly patients and 11/29 (37.9%) young patients(p = 0.011). Similarly, high expression of SIRT2 was more commonly observed in 58/99 (58.6%) elderly patients than 8/29 (27.6%) young patients(p = 0.003). In all patients high SIRT2 expression was associated with comorbid DM, and stage of CRC were not associated with SIRT1 or SIRT2 expression status. Comparison of Kaplan-Meier survival curve using log rank test revealed that high expressions of SIRT1 and SIRT2 were significantly associated with worse prognosis (median OS 24.9ms vs 38.6ms, p = 0.027) and better prognosis (median OS 37.9ms vs 17.3ms, p = 0.006) respectively in elderly patients. No prognostic significances were observed in younger patients. In multivariate analysis, only high SIRT1 expression retained statistical significance as a poor prognostic factor in elderly patients with CRC. Conclusions: :High SIRT1 expression might become a significant poor prognostic factor for elderly CRC patients although further study is needed for younger patients to clarify the difference of expression according to the age between elderly and young patients with CRC. High SIRT2 expression showed association with comorbid DM, further studies are warranted to establish prognostic significance in CRC patients.