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 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.

APC mutations have been reported in lung squamous cell carcinoma and small-cell lung carcinoma, but rarely in lung adenocarcinoma. However, variants in the APC gene have not been well characterized in lung adenocarcinoma and their clinical significance is unclear. According to ClinVar, this particular variant is a likely benign germline variant (https://preview.ncbi.nlm.nih.gov/clinvar/variation/829/).

Germline APC mutations are characteristically associated with Familial Adenomatous Polyposis (FAP) that predisposes to carcinomas of the colo-rectum, stomach, duodenum, and thyroid. Recently somatic mutations in exon 15 of APC gene have been described in certain sporadic papillary thyroid carcinomas. The prognostic impact of these mutations remains unknown in such settings.