Significance of 8-OHdG expression as a predictor of survival in colorectal cancer

Abstract Background Although oxidative stress regulates essential signaling pathways, oxidative DNA damage causes cancer initiation and progression. Given that the relationship between oxidative stress and colorectal cancer (CRC) remains poorly understood, we confirmed the clinical significance of 8-hydroxy-2' deoxyguanosine (8-OHdG), a representative oxidative stress marker, and its potential as a survival predictor. Methods This study was 564 patients who underwent CRC surgery at Gachon University Gil Medical Center between April 2010 to November 2012. We aimed to confirm the clinical significance of 8-OHdG and its role as a survival predictor. To this end, 8-OHdG levels in CRC patients were evaluated by immunohistochemistry, followed by univariate/multivariate analysis and survival analysis according to the pathological stage. Results 8-OHdG expression was associated with cell differentiation. Furthermore, the 5-year disease-free survival (DFS) and disease-specific survival (DSS) hazard ratios (HRs) of the low 8-OHdG subgroup were 1.41 (95% confidence interval (CI): 1.01–1.98, p = 0.04) and 1.6 (95% CI: 1.12–2.28, p < 0.001), respectively. When tumor node metastasis (TNM) staging and 8-OHdG expression were combined, the 5-year DFS and DSS HRs of patients with CRC with low 8-OHdG expression and advanced stage III/IV cancer were 6.85 (95% CI: 4.09–11.50, p < 0.001) and 8.24 (95% CI: 4.66–14.59, p < 0.001), respectively, compared to those with high 8-OHdG expression and early stages I/II cancer, indicating a poor prognosis. Conclusions Combining the currently commonly used TNM stage with the novel biomarker 8-OHdG identified in CRC patient tissues may result in a more accurate patient diagnosis and prognosis.