Variation of α-methylacyl-CoA racemase expression in prostate adenocarcinoma cases receiving hormonal therapy

α-methylacyl-CoA racemase (AMACR) is widely used as a diagnostic marker of prostate adenocarcinoma. It is also used to identify residual adenocarcinoma cells in posthormonal therapy cases. However, there have been very few studies on the relationship between hormonal therapy, which is also called androgen withdrawal therapy and AMACR expression. Here, we carried out a study on AMACR expression in paired pre- and posthormonal therapy prostate adenocarcinoma cases using an immunohistochemical method and a digital imaging system to elucidate the relationship between AMACR expression and hormonal therapy. This study showed that AMACR expression was decreased in 65 of 98 paired cases after hormonal therapy (Mann-Whitney U test, P < .05). Wilcoxon analysis also demonstrated a difference in the AMACR digital average expression in all 98 cases (P < .0001). However, this variation in AMACR expression did not seem to have any relevance to the response to hormonal therapy (P = .5386). We propose that AMACR, as a diagnostic marker, should be carefully used in posthormonal therapy cases. Further investigation of the relationship between AMACR expression and androgen or androgen receptors may provide new insight into novel preventive and curative medicine for prostate adenocarcinoma.