Factors associated with endoscopic treatment decisions for T1b or more deeply invading colorectal cancers

Surgical resection for colorectal cancer （ CRC ） that deeply invades the submucosa （ ≥1,000 µm ） （ T1b ） has been recommended to reduce the potential risk of lymph node metastasis. In clinical settings, cases of pathological T1b exist, and these cases are treated with endoscopic resection （ ER ） for various reasons. However, factors that influence the choice of ER to treat T1b CRC remain unknown. Therefore, in this study, we investigated the factors associated with the choice of endoscopic treatments in patients diagnosed with pathological T1b or a more deeply invading CRC. To achieve this aim, we conducted a case series investigation of the previously conducted endoscopic diagnoses, after which we selected treatments for colorectal lesions. The case series comprised 83 lesions endoscopically diagnosed as early CRC, which was subsequently reviewed by eight endoscopists with various levels of experience in magnifying colonoscopy at Showa University Hospital. Then, pathological T1b or T2 lesions were extracted from the case series. We also assessed factors related to ER selection for these lesions using multiple logistic regression and analyzed their contributions using decision tree analysis. Eighteen cases with pathological T1b or more deeply invading lesions were extracted, and the analyses were conducted using 144 data obtained from these 18 lesions as interpreted by the eight reviewers. With multivariate logistic regression, a low estimation level for T1b and high confidence to perform ER were identified as independent factors affecting the selection of ER for T1b. The decision further indicated that confidence levels to perform ER influenced treatment selection, especially in lesions diagnosed as probable T1b. Our study therefore demonstrated that factors affecting the selection of ER to treat T1b CRCs were low estimations during endoscopic diagnosis and high confidence to conduct the ER procedure.