Abstract Aim Evidence exists of radiological upstaging of rectal cancers due to fibrosis caused by endoscopic tattooing. We review investigated whether endoscopic tattooing for colonic lesions resulted in subsequent radiological upstaging. Methods A retrospective review was performed of patients endoscopically diagnosed with colonic cancer and undergoing surgery over three years at a single centre. This included patients who underwent both CT imaging prior to, and after colonoscopy with biopsy +/- tattoo. Radiological and operative staging was subsequently compared. Emergencies, those with no colonoscopy or pre-operative imaging and rectal cancers were excluded. Data were obtained from Somerset register and electronic care records. Data were analysed using chi squared test. Results A total of 175 patients were included. 49 patients had CT imaging prior to their colonoscopy, 51 patients had colonoscopy and biopsy prior to imaging; a further 75 patients had biopsy and tattoo prior to imaging. Patients with pre-endoscopy imaging were considered the control group, and patients with biopsy only were calculated separately as they were considered potential confounders (Table 1).Table 1:UpstagedDownstagedSame stagingPre-endoscopy imaging191713Biopsy only131622Tattoo and biopsy212727 Overall, there was no significant difference between groups (p=.429), although 7 reports specifically mentioned potential impact of recent biopsy and tattoo affecting image interpretation. Conclusion Our results do not suggest biopsy or tattooing alters pre-operative staging, although it is possible that radiologists may have evolved their interpretation to account for any potential differences.