Background
Hepatocellular carcinoma (HCC) is the fifth most common malignancy and the third leading cause of cancer-related deaths worldwide [
1]. Although there have been many advances in the treatment of HCC, the outcome is still not satisfactory [
1,
2]. Since a long lasting inflammatory process like cirrhosis continually induces hepatocarcinogenesis, there are limitations on curative therapy. Besides known prognostic factors representing tumor status and liver function [
3], it is now clear that inflammation plays a significant role in tumor progression [
4]. In this situation, C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), indicators of inflammation, have been suggested as surrogate markers for a relationship between inflammation and cancer [
5].
CRP has been identified as a prognostic factor for HCC [
6‐
10] as well as other various malignancies, such as gastrointestinal tumor, renal cell cancer and ovarian cancer [
5,
11]. It is an acute phase reactant, synthesized in the liver [
12], and regulated by proinflammatory cytokines, like interleukin (IL)-6, which plays an important role in carcinogenesis [
13]. The NLR has recently been evaluated as a predictor of prognosis of HCC [
14‐
16] as well as other malignancies like colorectal cancer, gastric cancer, breast cancer and ovarian cancer [
5,
17‐
20]. It has been shown that high levels of NLR could predict a risk of recurrence and survival in patients with various malignancies.
HCC is unique among other cancers, in that its prognosis not only depends on the tumor characteristics but also on the hepatic functional reserve. In this respect, it seems to be more relevant to understand inflammatory process in hepatocarcinogenesis and evaluate its effect on the patient prognosis. To date, there have been no comprehensive data on the relationship between the inflammatory markers and hepatic reserve and tumor status in HCC. In addition, the significance of both CRP and NLR in HCC survival has not yet been explicitly studied in one research.
In the present study, we therefore evaluated the clinical value of CRP as well as NLR measured at the same point in time in clinical outcome in a large number of patients with HCC. In addition, changes in CRP and NLR after treatment were examined in relation to the treatment response. The present findings show the prognostic utility of both CRP and NLR as a surrogate marker for efficacy in treatment as well as HCC survival.
Discussion
The present study focused on the predictive value of CRP and NLR in the outcome of patients with HCC. From the analysis of a large cohort, we found that elevated CRP and NLR independently predicted worse survival in patients with HCC. In this study, CRP and NLR were utilized as prognostic indicators of HCC which appeared to be more evident when used in combination. This is probably due to the significant synergistic effect of the two inflammatory markers. Moreover, these markers correlated well with tumor response, as evidenced by serial measurements. The significant prognostic role of CRP and NLR is supported by the evidence that the levels of both markers displayed a linear relationship with the progressing stage of tumor and Child-Pugh classification, known as the two key prognostic factors for HCC.
There have been not yet clear explanation how elevated CRP and NLR would be responsible for tumor progression. Some studies have compiled the possible roles of CRP in cancer development as follows: i) anti-apoptotic activity and tumorigenic potency by over expression of IL-6, ii) T cell impairment, iii) resistance to chemotherapy, and iv) increased levels of serum angiogenic factors [
23]. The levels of CRP have been inversely related to tumor-infiltrating CD4+ T-lymphocytes within the tumor microenvironment, which in turn carriers a poor prognosis [
24]. Because not only normal hepatocytes but also hepatoma cells can produce serum CRP [
25], it could be regarded that elevated CRP is related to hepatic tumor burden, and this has supporting evidence [
7].
Although measured easily, NLR is more complicated due to its special feature as a combined factor of inflammation and host immune reaction. Increased counts of neutrophil can provide an adequate environment for tumor growth and even metastasis via angiogenesis. One study showed that neutrophils enhance tumor invasion via paracrine regulation mediated by neutrophil-derived hepatocyte growth factor [
26]. The accumulated IL-17-recruited neutrophils into peritumoral stroma of HCC were the major source of matrix metalloproteinase-9, which stimulates proangiogenic activity in HCC [
27]. Circulating vascular endothelial growth factor, a key proangiogenic factor, is contained in granulocyte, particularly in the neutrophils [
28]. Neutrophil can contribute to cancer metastasis via promoting motility of cancer cells and adhesion to hepatic sinusoids [
29,
30]. Since neutrophil could also suppress T cell activation through the production of arginase, nitric oxide and reactive oxygen species [
31], it induces depletion of lymphocyte-mediated immune response. Weaker immune reaction due to relative lymphocytopenia and elevated NLR could explain for depletion of tumor-infiltrating lymphocytes that are independently predictive of cancer-specific survival [
32].
With multivariate analysis, the present study revealed Child-Pugh class, tumor size, tumor multiplicity, presence of PVT, AFP, CRP and NLR as independent factors predictive of outcome of HCC. A recent study evaluating CRP and NLR in transplant recipients with HCC showed that CRP did not affect overall patient survival, but NLR did with statistical significance [
33]. The discrepancy could be due to some differences in assays measuring CRP and the study population. Our study employed a high-sensitivity CRP with cut-off value 6.3 mg/L, whereas the study detected CRP with a conventional sensitivity with cut-off value 1 mg/dL (= 10 mg/L). Additionally, our study recruited patients with various stages of HCC undergoing different treatment modalities, which is a distinction to the study recruiting patients with limited stages of HCC undergoing transplantation, which could result in no more lasting inflammation. There is no consensus on the cut-off value for NLR. It has been therefore set empirically between 2.42 and 5 in studies [
5,
14‐
20]. In this analysis, the cut-off value of 2.3 for NLR offered the most significant association with the patient outcomes. Further studies are needed to determine the optimal cut-off point of CRP and NLR in predicting prognosis in patients with HCC.
In our results, it is interesting to note that an elevated CRP level was strongly associated with an elevated NLR. It seems to be due to some relationship between these two markers in terms of host inflammation and immune reaction, as evidenced by the observations that high CRP levels associated with inflammation are inversely related to low-level tumor lymphocyte infiltration, which may contribute to an elevated NLR [
24]. Although they had modest individual associations on the prognosis of the patients, the significance was quite stronger when used in combination. It is of note that both CRP and NLR levels were significantly related to tumor burden and underlying hepatic reserve, known as the two key determinants of HCC survival, showing a linear positive relationship with tumor stages or Child-Pugh classes. Thus, their role as prognostic indicators seems to be synergistically enhanced with combined use of them, as presented in our survival analysis.
Moreover, our results showed that patients with elevated CRP and NLR had worse treatment response, while those with a low-level of CRP and NLR had more favorable response. Consistent with survival analysis, there were significant differences in tumor response on the combined use of serum CRP level and NLR. Serial measurements of CRP and NLR exhibited a reduction in CRP and NLR among responders as well as their rise in progressive disease during treatment. Thus, it is expected that the outcome of treatment response before and during management would be predictable to some extent with the levels of CRP and NLR.
The current study has some limitations. There is some heterogeneity in treatment used for HCC, and the majority of the patients received TAC-based loco-regional therapy, with limited number of surgical cases, which could have affected the outcome. However, the prognostic effect of those inflammatory markers was still apparent when analyzed specifically in selected patients receiving loco-regional therapies. Although there are many other conditions affecting the levels of CRP and NLR, like an infectious state and autoimmune disease, the possibility may be minimized because most of those markers were indeed tested prior to treatment, without evidence of serious infection. Rather, the results of our study could be reliable, because we described the largest cohort to date of consecutive patients and provided comprehensive data from serial measurements of CRP and NLR simultaneously, which have not been explicitly evaluated thus far.
Jeong Won Jang, Division of Hepatology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, #222 Banpo-daero 22-gil, Seocho-gu, Seoul 137-701, Korea, Telephone: +82-32-280-5866, Fax: +82-32-280-5987.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
BSO and JWJ participated in the design of the study, performed the statistical analysis and interpretation of data, and drafted the manuscript. JHK, CRY and KWC recruited patients to the study. CSK is a radiation oncologist who contributed to treat the patients. HSJ is an interventional radiologist who contributed to treat the patients. SL is a clinical pathologist who participated in the study design. All authors read and approved the final manuscript.