[Colorectal cancer with β-catenin protein expression deficiency: a clinicopathological analysis].

Objective: To investigate the clinicopathological features and molecular characteristics of β-catenin-deficient colorectal cancer. Methods: The clinical, pathological and molecular features of 11 colorectal cancers with β-catenin protein loss diagnosed at the 960th Hospital of People's Liberation Army of China, from January 2012 to November 2022 were analyzed. Results: Among the 11 patients, 3 were males and 8 were females. Their age ranged from 43 to 74 years, with the median age of 59 years. Six were in the left colon and 5 were in the right colon. One of the 11 cases had lymph node metastasis, 10 cases were well and moderately differentiated adenocarcinoma, and 1 was mucinous adenocarcinoma. Eight cases were of TNM stage T4, 2 of T1 stage and 1 of Tis stage. β-catenin protein was not detected using immunohistochemistry. Sanger sequencing revealed the presence of fragment-deletion mutation in exon 3 of CTNNB1 gene, resulting in loss of β-catenin protein expression. Conclusion: β-catenin deficiency is present in a small number of colorectal cancers and may be associated with exon 3 mutations of CTNNB1 gene.