DJ-1 is a useful biomarker for invasive extrahepatic cholangiocarcinoma

We have previously reported that DJ-1 protein is up-regulated in cholangiocarcinoma compared with non-neoplastic epithelium of the bile duct in a study using liquid-chromatography mass spectrometry-based proteomics. The aim of this study was to clarify whether DJ-1 expression offers a biomarker for patients with invasive extrahepatic cholangiocarcinoma (EHCC) who undergo surgical resection with curative intent. Positive immunohistochemical (IHC) staining of DJ-1 was significantly more frequent in the cytoplasm of 96 invasive EHCCs (n = 28, 29.2%) than in that of 66 non-neoplastic epithelial lesions adjacent to invasive EHCC (n = 7, 10.6%; P = .006). No significant difference in clinicopathological features was evident between invasive EHCC patients with negative (n = 68) and positive (n = 28) IHC staining. However, negative IHC staining for DJ-1 in cytoplasm was selected as an independent risk factor for adverse prognosis on multivariate analysis (P = .004, hazard ratio 2.13, 95% confidence interval 1.28-3.57). Serum levels of DJ-1 in 16 invasive EHCC patients with metastasis were compared with 12 invasive EHCC patients without metastasis. Serum levels of DJ-1 tended to be higher in 16 patients with metastasis (median, 40.9 ng/ml) than in 12 patients without (27.6 ng/ml, P = .137). In addition, patients with high serum levels (≥ 40 ng/ml) of DJ-1 tended to have metastasis more frequently than those without (P = .054, Fisher's exact test). We concluded that IHC staining pattern and serum level of DJ-1 in patients with invasive EHCC might be predictive of prognosis and metastasis, respectively.