Abstract. At present, there is a high incidence of viral hepatitis and high mortality rates due to hepatocellular carcinoma (HCC) in China. In the current study, the quantification of antibodies against the cancer-testis antigen sperm-associated antigen 9 (SPAG9), alone and combined with α-fetoprotein (AFP), were evaluated as biomarkers for the diagnosis of HCC. The levels of anti-SPAG9 antibody and AFP were quantified in serum samples from patients with HCC and hepatitis or cirrhosis, as well as healthy volunteers. The results revealed that the serum levels of anti-SPAG9 immunoglobulin G antibody in patients with HCC were significantly higher compared with those in patients with hepatitis/cirrhosis and healthy controls. Using receiver operator characteristic curves, the area under the curve (AUC, 0.870) of SPAG9 as a diagnostic marker of HCC was significant [P<0.001; 95% confidence interval (CI), 0.793-0.947], whereas the AUC of AFP was 0.832 (P<0.001; 95% CI, 0.736-0.928). Serum anti-SPAG9 antibody levels exhibited significant potential for the differential diagnosis of HCC, with an AUC value of 0.729, (P=0.008; 95% CI, 0.559-0.899). Similarly, serum AFP levels exhibited significant value for the differential diagnosis of HCC, with an AUC value of 0.842 (P<0.001; 95% CI, 0.732-0.953). When combined with quantification of AFP, the diagnostic sensitivity and specificity of anti-SPAG9 levels were increased. In summary, the results suggested that anti-SPAG9 antibody is a potential early diagnostic marker of HCC.
IntroductionHepatitis B virus (HBV) and hepatitis C virus (HCV) infections are major risk factors for the development of human hepatocellular carcinoma (HCC) (1-3). The incidence of HCC in China is ~100/100,000 population, and a principal component of the attributable risk is chronic HBV infection (4), with >50% of the global HCC burden attributed to HBV (5). In China, ~10% of patients with HCC suffer from HCV infection, and certain patients have HBV and HCV co-infections (6). In the USA, Europe and Japan, >50% of current cases of HCC are attributable to HCV infection, and the majority of these patients have cirrhosis (7-9). The time from initial diagnosis of chronic hepatitis to the development of HCC may span several decades; once cirrhosis is established, HCC develops at a yearly rate of 1-4% (10).In China, the majority of patients with HCC present with advanced-stage disease, and HCC has become the second leading cause of mortality (11). Early diagnosis relies on non-invasive biomarkers, imaging and clinical parameters, with markers such as α-fetoprotein (AFP), the proportion of the fucosylated isoform of AFP to total AFP, AFP-L3 and des-gamma-carboxy-prothrombin (DCP) being Food and Drug Administration-approved for use in the surveillance of high-risk populations (12,13). However, the clinical value of these biomarkers is a subject of debate (14). In Japan, three biomarkers are combined for surveillance (15,16), and this combined testing has a high level of sensitivity and specificity (17,18). In Ch...