Hepatocellular carcinoma (HCC) is the most common form of liver malignancies worldwide [4, 11]. There are many risk factors for HCC recurrence and progression, including tumor size, associated cirrhosis, HBV infection, HCV infection, histological grade of tumor differentiation, vascular permeation, and the absence of capsule [12,13,14].

The molecular pathogenesis of HCC disease remains mysterious even after both causative factors and cellular changes have been recognized [15,16,17,18]. Furthermore, therapeutic modalities for HCC remain limited. More interpretation of the underlying biology of HCC is needed for further development in subsequent targeted therapies against essential molecular mechanisms of HCC [19].

S100A4 and other S100P (proteins) have been studied in many in vitro studies on HCC cell lines, revealing higher S100P levels than normal nonmalignant hepatocytes, which frequently lack S100P. Also, silencing of endogenous S100P was observed to decrease HCC cell growth by Kim et al. [7].

The present study reported that expression of S100A4 in HCC patients is associated with metastasis, higher grades of HCC, microscopic vascular embolization, and tumor necrosis. These findings may implicate that more biologically aggressive tumors are related to the positivity of S100A4 in tumor tissues.

Cui et al. (2006) reported that S100A4 was overexpressed only in the metastatic cells among other metastasis candidate proteins in HCC cell lines and was selected for further series of assays. The authors suggested that S100A4 might contribute to HCC invasion and metastasis through two matrix metalloproteinase (MMP9) secretion regulation paths and strengthened motility and invasion properties [6].

Yan et al. (2013) reported that S100A4 expression was significantly higher in liver cancer-associated mesenchymal stem cells (LC-MSCs) compared with liver normal MSCs (LN-MSCs) from adjacent cancer-free tissues. They also revealed that S100A4 secreted from LC-MSCs has a role in HCC progression and may be a potential therapeutic target [20].

In a study on mainly HBV patients, Liu et al. found that S100A4 correlated with tumor differentiation, invasion, recurrence, and overall survival and concluded that it could be a valuable marker of tumor aggressiveness and prognosis [21].

In the current study, there was a significant positive correlation between AFP level and S100A4 expression. At the same time, Liu et al. found no significant association between S100A4 expression and AFP level [21].

On the other hand, Cho et al. found that S100A4 expression in HCC was not statistically correlated with clinicopathologic parameters, including histologic grade, stage, capsular invasion, intrahepatic metastasis, and portal vein invasion. Also, they found that gene amplification of S100A4 was not associated with clinical parameters [22].

Sample sizes, population admixture, differences in ethnic backgrounds, differences in etiology, and different criteria for selection of target population may all contribute to these conflicting results and discrepancies.

The primary etiology of liver disease in HCC patients significantly impacts patient outcome and cannot be neglected as a cofactor with other variables [23, 24]. Many studies concluded that survival is significantly better in HCV-related HCC than in HBV-related HCC. Cantarini et al. reported that hepatitis C virus-related HCC has a lesser aggressiveness than hepatitis B virus-related HCC, as HCV-related HCC becomes clinically manifest once they have reached an advanced stage [17, 25]. Sinn et al. concluded that HCV-related HCC has a better prognosis than HBV [26]. The discrepancy in survival has also been previously described in breast cancer studies with S100A4. The discrepancy has been attributed to fewer case numbers, the difference in stages of disease included in different studies, a relatively short period of follow-up, and differences in sample storage conditions or fixation methods [27, 28].

GPC3 has been established as a diagnostic marker for HCC. Further studies have evaluated its value in prognosis suggesting its role as a promising prognostic biomarker. Many meta-analytic studies confirmed that GPC3 expression is of prognostic value as it was correlated with shorter overall survival (OS) and disease-free survival (DFS) of HCC patients [29].

In the current study, the diagnostic value of GPC3 in HCC has been confirmed, supporting its established value. However, regarding its prognostic value, its expression was only correlated with the time of recurrence of HCC, and there was no correlation with patient overall survival. Similar results were obtained with Chen et al., who revealed that GPC3 expression was a significant independent prognostic factor for disease-free survival. However, overall survival was not affected, but this study included only cases of early HCC [29].

Unlike most previous studies, the present study found no association between GPC3 and tumor differentiation and other clinicopathological parameters [29].

This conflict between this study and previous studies might be explained by some limitations which were addressed in some of those studies. First, positive results were more published than negative ones, suggesting a potential risk of bias. In addition, the total number of included studies and the total sample size were relatively small, which might influence the validity of the analysis to some extent [29]. Moreover, many of these studies were based on the Asian population. Also, there was a lack of data about other races. In addition, the IHC analysis technique has many related factors such as the type of antibody used, detection method, evaluation method of results, and interobserver variation that lead to the heterogeneity of IHC studies [29].

There are a few limitations to this study. All the patients were HCV-induced HCC, and no comparison was made with other causes of liver disease. The small sample size (70 patients), a short period of follow-up, and operative complications may have an impact on survival, and it was not clarified here. Moreover, in patients who had decompensated liver disease, there was a defect in follow-up for recurrence of HCC, suggesting a possibility of missed recurrence or metastasis in this group of patients.