Abstract: Objective To evaluate the association between SLC22A1 expression and the outcomes of hepatocellular carcinoma
(HCC) patients. Methods A tissue microarray of 303 HCC and matched adjacent noncancerous liver tissues (ANLTs) were
constructed. The expression of SLC22A1 was tested by immunohistochemistry (IHC) and scored by two pathologists according
to a 12-score scale (a score>6 was defined as high expression, and a score≤6 as low expression). The correlation of SLC22A1
expression with the clinicopathological features and the patients’ outcome was analyzed. Results All the ANLTs had a IHC
score of 12, as compared to only 29 (9.6%) of the HCC tissues. The patients were divided into 2 groups based on the IHC
scores: 59% (180/303) in low expression group and 41% (123/303) in high expression group. The disease-free survival (DFS)
rates and overall survival (OS) rates were significantly lower in low SLC22A1 expression group than in the high expression
group. The 1-, 3-, and 5-year DFS rates were 43%, 31% and 27% in the low expression group, and were 58%, 47% and 43% in
the high expression group, respectively. The 1-, 3-, and 5-year OS rates were 66%, 38% and 32% in low expression group, and
were 80%, 57% and 50% in the high expression group, respectively. A low expression of SLC22A1 was positively correlated
with the tumor diameter, BCLC stage, tumor differentiation, and AFP levels (P<0.05), and was an independent predictor of
poor overall survival (HR=1.454; 95% CI, 1.050-2.013). Conclusion Down-regulation of SLC22A1 is a malignant feature and a
potential prognostic marker of HCC.