Overexpression of Brefeldin A-inhibited Guanine Nucleotide-exchange Protein 3 in Patients with Extramammary Paget's Disease.

Overexpression of brefeldin A-inhibited guanine nucleotide-exchange protein 3 (BIG3) has been reported in estrogen receptor α-positive breast cancer (BC) tissues, with high BIG3 expression strongly associated with poor prognosis in patients with BC. This study investigated the expression pattern of BIG3 in patients with extramammary Paget's disease (EMPD) and evaluated its clinical significance. Sixty-one tissue and 30 serum samples were collected from patients with EMPD. Immunohistochemistry showed that most EMPD tissues were positive for BIG3 (57/61, 93.4%), and strong BIG3 intensity correlated with the degree of invasiveness, lymph node/distant metastasis, and overall survival. Serum BIG3 levels in EMPD patients with invasive lesions were significantly higher than those in patients with in situ lesions and correlated with the serum concentration of cytokeratin 19 fragment. Therefore, BIG3 expression may serve as a prognostic marker in patients with EMPD.