MUC16 and gastric adenocarcinoma: As the third most frequently mutated gene according to The Cancer Genome Atlas (TCGA), MUC16 (OMIM 606154) encodes a membrane-spanning mucin, comprising a tandem repeat region sandwiched between N-terminal and C-terminal domains.3,4 Tumor antigen 125, residing in the tandem repeat region, is a common clinical biomarker to monitor epithelial ovarian cancer.3 A recent study5 reported that MUC16 mutation may be associated with elevated tumor mutational burden and superior overall survival (OS) in patients with gastric adenocarcinoma.