PSMA expression in hepatic colorectal cancer metastasis.

[BACKGROUND] Prostate-specific membrane antigen (PSMA) is expressed in the neovasculature of various malignancies, such as colorectal cancer (CRC) and hepatocellular carcinoma (HCC). However, PSMA expression in hepatic CRC metastasis has not been studied in detail.

[METHODS] The PSMA expression in primary CRC and corresponding hepatic metastasis was evaluated by immunohistochemistry in a metastatic CRC cohort (n = 56), which was divided into subgroups according to treatment history and timing of metastasis. Demographic and histological characteristics of primary CRC were collected and their relationships with PSMA expression were examined. Additionally, the PSMA expression in resected HCC (n = 76) was compared with that of hepatic CRC metastasis.

[RESULTS] In primary CRC, PSMA level showed a positive association with tumor size. Lower PSMA expression in hepatic metastasis was associated with higher primary CRC grade, advanced pTNM stage at the time of CRC resection, presence of tumor deposit, and unresectability of metastatic lesion. PSMA expression in primary CRC correlated with that in hepatic metastasis only in concurrent and untreated metastasis subgroup. PSMA expression in primary CRC and hepatic metastasis, regardless of treatment history and timing of metastasis, was not significantly different from that of HCC.

[CONCLUSIONS] Several adverse pathological features of primary CRC were associated with a lower PSMA expression in hepatic metastasis. PSMA expression in hepatic metastasis correlated with that of primary CRC only in concurrent and untreated subgroup. Primary HCC and hepatic CRC metastasis show comparable levels of PSMA expression.