Evidence for upregulated repair of oxidatively induced DNA damage in human colorectal cancer

► We report on oxidatively induced DNA damage in colorectal cancer. ► We measured the levels of major DNA base lesions in cancerous colorectal tissues and their surrounding normal tissues of patients. ► We used mass spectrometry and found significantly lower levels of DNA lesions in cancerous tissues than those in non-cancerous tissues. ► Our results suggest that repair of oxidative DNA damage may be up-regulated in colorectal tumors, compared to normal colorectal tissues. ► The type of DNA base lesions identified suggests the upregulation of both base excision and nucleotide excision pathways.