Alpha-methylacyl-CoA racemase (AMACR) expression in epithelial ovarian cancer

Alpha-methylacyl-CoA racemase (AMACR) is involved in the cellular metabolism of fatty acids. It is a prognostic factor in prostate and colorectal cancer. So far, little is known about its expression and prognostic role in ovarian cancer. We investigated the expression of AMACR in a total of 420 ovarian tumors (388 carcinomas, 32 borderline tumors) by immunohistochemistry on tissue microarrays of two independent patient cohorts. In both cohorts, cytoplasmic AMACR expression was identified in 11.8% (16/136) and 5.4% (13/239), respectively, of the ovarian carcinomas. In contrast, borderline tumors did not show any AMACR expression. AMACR expression was significantly associated with histological subtype, FIGO stage, and grade in one cohort and low estrogen receptor levels in the other cohort. In univariate analysis, AMACR expression was significantly associated with poor overall survival (log rank, p = 0.006) and an independent prognostic factor in a multivariate analysis (HR 3.3; CI 1.3-7.9; p = 0.008) but could not be verified in the second cohort. Unlike in other tumor entities, AMACR expression does not seem to have an unequivocal prognostic impact in ovarian cancer. The prevalence may limit the value of AMACR for the differential diagnosis between metastatic colorectal carcinomas and primary ovarian carcinomas, whereas the association with estrogen receptor expression deserves further studies.