Somatic APC mutations are common events in colorectal adenocarcinomas, reported in up to 76% of the cases. Loss of normal APC function is known to be an early event in both familial and sporadic colon cancer pathogenesis, occurring at the pre-adenoma stage. APC mutations do not appear to significantly affect the prognosis of colorectal cancer patients. While there are a number of small molecule inhibitors in development that target the Wnt pathway, there is currently no matched targeted therapy available for colorectal cancer patients harboring an APC mutation.

The APC gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. APC promotes rapid degradation of beta-catenin and participates in Wnt signaling as a negative regulator. APC is also involved in other processes including cell migration, cell adhesion, transcriptional activation and apoptosis. Germline defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Disease-associated mutations tend to be clustered in a small region designated as the mutation cluster region (MCR) and result in a truncated protein product. Somatic APC mutations are rare in adenocarcinoma of small intestine and further studies are needed to explore the clinical value of these mutations. Results should be interpreted in conjunction with other laboratory and clinical findings.

The APC gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. APC promotes rapid degradation of beta-catenin and participates in Wnt signaling as a negative regulator. APC is also involved in other processes including cell migration, cell adhesion, transcriptional activation and apoptosis. Germline defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Disease-associated mutations tend to be clustered in a small region designated as the mutation cluster region (MCR) and result in a truncated protein product. A study of APC gene mutations in gastric carcinomas did not find an obvious relationship between the APC mutation and tumor size, depth of invasion, node metastasis or clinical stages, indicating a limited role of the APC mutation in predicting prognosis of gastric carcinomas. APC mutations were significantly more frequent in intestinal type gastric cancers as compared with diffuse type gastric cancers, suggesting that APC gene is not only a predisposing gene in colorectal cancer but also a predisposing gene in intestinal type of gastric cancer.