Endoscopic localization of colorectal cancer: study of its accuracy and possible error factors

Abstract

Introduction: accurate preoperative localization of colorectal cancer (CRC) is very important, with a wide range of published error rates.

Aims: to determine accuracy of endoscopic localization of CRC in comparison with preoperative computed tomography (CT). To analyse variables that could be associated with a wrong endoscopic localization.

Patients and methods: endoscopic and CT localization of a series of CRC without previous surgery were reviewed. We studied the concordance between endoscopic and radiologic localization against operative findings comparing accuracy of endoscopy and CT. We analysed the frequency of wrong endoscopic diagnoses with regard to a series of patient, endoscopy and tumor variables.

Results: two hundred thirty seven CRC in 223 patients were studied. Concordance with surgical localization was: colonoscopy = 0.87 and CT = 0.69. Endoscopic localization accuracy was:91.1%; CT: 76.2%: p = 0.00001; OR = 3.22 (1.82-5.72). Obstructive cancer presented a higher rate of wrong localization: 18 vs. 5.7% in non-obstructive tumors (p = 0.0034; OR = 3.65 (1.35-9.96). Endoscopic localization mistakes varied depending on tumor location, being more frequent in descending colon: 36.3%, p = 0.014; OR = 6.23 (1.38-26.87) and cecum: 23.1%, p = 0.007; OR = 3.92 (1.20-12.43).

Conclusions: endoscopic accuracy for CRC localization was very high and significantly better than CT accuracy. Obstructive tumor and those located in the descending colon or cecum wereassociated with a significant increase of the error risk of CRC endoscopic localization.