Guanylyl cyclase C is a specific marker for differentiating primary and metastatic ovarian mucinous neoplasms.

AIMS: The aim was to assess the value of GCC in distinguishing primary ovarian mucinous neoplasms from metastatic mucinous adenocarcinomas with ovarian involvement. Guanylyl cyclase C (GCC) is a brush border membrane receptor for the endogenous peptides guanylin and uroguanylin, and the homologous diarrhoeagenic bacterial heat-stable enterotoxins that is selectively expressed by epithelial cells from the duodenum to the rectum, but not by normal epithelia of the stomach or oesophagus, or normal extramucosal cells in humans.

METHODS AND RESULTS: Fifty ovarian tumours: 27 primary ovarian mucinous neoplasms (seven cystadenomas, 10 borderline tumours and 10 cystadenocarcinomas) and 23 metastatic mucinous adenocarcinomas with ovarian involvement [13 colorectal adenocarcinomas, four gastric adenocarcinomas, six appendiceal mucinous tumours (four adenocarcinomas, one with neuroendocrine features, and two appendiceal mucinous cystadenomas)] were studied. For primary ovarian mucinous neoplasms, 25 of 27 were negative for GCC. Twelve of 13 cases of colorectal adenocarcinoma (except for one neuroendocrine adenocarcinoma) were positive for GCC. Three of four appendiceal mucinous adenocarcinomas were positive for GCC in both the primary and metastatic tumours (except for one neuroendocrine adenocarcinoma). Two of two appendiceal mucinous cystadenomas were positive for GCC. Of four cases of gastric adenocarcinoma with ovarian involvement, only one (primary tumour) exhibited focal GCC staining.

CONCLUSIONS: GCC is a useful marker for differentiating between primary and secondary ovarian mucinous neoplasms.