The potential role of Vascular Endothelial Growth Factor for hepatocellular carcinoma screening: a systematic review

Introduction

By 2040, the World Health Organization (WHO) predicts that nearly 30 million people will be affected by cancer, with liver cancer being one of the most lethal types of the disease globally. The increased prevalence of liver cancer around the world is concerning for global health. Hepatocellular carcinoma (HCC), the most prevalent form of liver cancer worldwide, is predicted to result in more than one million fatalities annually by 2025. Between 2020 and 2040, there is expected to be a 55.0% increase in the annual number of new cases of liver cancer, with 1.4 million potential cases. In 2040, there will be 1.3 million liver cancer-related mortality, up 56.4% from 2020. HCC is a crucial societal issue for the ensuing 20 years.¹

HCC is the sixth most often diagnosed cancer, according to Global Cancer Incidence, Mortality, and Prevalence (GLOBOCAN) 2020. With a relative 5-year survival rate of about 18%, HCC is the third most frequent cause of cancer-related mortality globally. HCC causes 830,000 deaths yearly.²

HCC is a cancerous tumor that develops from hepatocytes, the primary parenchyma cells in the liver.³ Only a few of the numerous biomolecular failures implicated in the complex pathophysiology of HCC include immunomodulation, epithelial-to-mesenchymal transition, increased HCC stem cell dysregulation, DNA methylation alteration, chromosomal instability, cell cycle dysregulation, and microRNAs. Among the etiologies that have been connected to the development of HCC include viral infections, particularly those brought on by the hepatitis B and hepatitis C viruses, chronic alcohol use-related liver disease, non-alcoholic fatty liver disease, and aflatoxin exposure.³

The genetic region located on the fourth chromosome, believed to contain the coding sequence for 3’-phosphoadenosine 5’-phosphosulfate synthase 1 (PAPSS1), has the capacity to regulate the susceptibility to HCC in individuals with hepatitis B virus (HBV) infection. This susceptibility is influenced by various other genetic factors and syndromes that also exert a substantial influence.⁴

The principal pathogenic mechanism contributing to oncogenesis in HBV infection involves the integration of the viral genome into the host genome. Approximately 60% of HCC cases can be attributed to viral genome insertion within the telomerase reverse transcriptase (TERT) promoter regions of the human genome.⁵ In contrast, chronic inflammation resulting from long-term hepatitis C virus (HCV) infection, accompanied by fibrosis, necrosis, and regeneration, is a key factor contributing to HCC development in patients with hepatitis C. Molecular indicators of liver carcinogenesis include the detection of viral structural and non-structural proteins (such as NS3, NS4A, NS4B, NS5A, and NS5B).

Non-alcoholic fatty liver disease (NAFLD) is characterized by an excess accumulation of fat in hepatocytes without a history of alcohol consumption. NAFLD frequently manifests in individuals with metabolic syndrome, which is characterized by abdominal obesity, hypertension, hypertriglyceridemia, and insulin resistance. Notably, NAFLD has emerged as a common cause of HCC worldwide, particularly in western countries.⁶

The prognosis for HCC indicates the expected survival period for a patient following diagnosis. Several critical factors are pivotal, including the liver’s functioning, the tumor’s size and stage, and the chosen treatment approach. The poor prognosis primarily stems from the fact that early-stage HCC often lacks symptoms, leading to delayed detection, and it exhibits significant resistance to conventional chemotherapy and radiotherapy.⁷ Research has established that the use of targeted chemotherapeutic drugs marginally enhances patient survival⁸ by only about 7-10 months.⁹ Understanding the likelihood of HCC development in high-risk individuals enables close monitoring, which, in turn, is linked to early detection, reduced mortality, fewer comorbidities, and extended life expectancy among this high-risk population.¹⁰

Elevated serum alpha-fetoprotein (AFP) levels, which are indicative of VEGF pathway activity, serve as a biological marker associated with a bleak prognosis in all stages of HCC. Studies have demonstrated that fluctuations in AFP levels are closely linked to clinical outcomes in systemic therapy, with higher levels being associated with tumor progression and lower levels with slower disease advancement. This impacts both overall survival and progression-free survival.¹¹ Proof-of-concept investigations in HCC, utilizing experimental biomarker enrichment, have yielded diverse results. Both tissue and circulating VEGF levels offer valuable predictive insights into the prognosis of HCC because they exhibit a positive correlation with AFP and possess strong predictive value for estimating overall survival.¹²

The majority of HCC exhibit hypervascularity, which is evident through characteristics like intrahepatic metastases, frequent portal vein invasion, and the supply of blood from the hepatic artery to the tumor. The formation of new blood vessels from pre-existing ones, known as angiogenesis, represents a crucial step in the growth, progression, and metastasis of HCC. Unlike healthy blood vessels, the arteries supplying tumors have a porous vascular structure and rapidly dividing endothelial cells. This creates challenges for the tumor in obtaining sufficient oxygen and nutrients, resulting in abnormal tumor microenvironments. One of the key factors contributing to tumor angiogenesis is the presence of vascular endothelial growth factor (VEGF).¹³

Protein molecules like VEGFA, VEGFB, VEGFC, VEGFD, and placental growth factor (PlGF) are part of the VEGF family, which consists of members sharing similar structural and functional characteristics. These substances become physiologically active in their homodimer or heterodimer forms, binding to cell surface-expressed tyrosine kinase (TK) receptors such as VEGFR1, VEGFR2, and VEGFR. VEGFs play a role in promoting cancer metastasis through several mechanisms. These mechanisms include the stimulation of tumor angiogenesis, the formation of leaky and disorganized blood vessels within tumors, the induction of tumor inflammation, alteration of tumor hypoxia, promotion of interactions between cancer cells and vascular endothelial cells by remodeling tumor vessels, and modification of the host microenvironment for metastatic spread. As a result, VEGF-induced cancer metastasis is implicated in various stages of the complex metastatic process.¹⁴

Research efforts have been directed towards exploring the potential prognostic significance of novel biomarkers associated with the carcinogenic processes in HCC patients. In this study, we undertook a systematic analysis to evaluate the prognostic significance of elevated levels of VEGF in both serum and tissue samples for assessing overall survival and disease-free survival (DFS) in individuals with HCC. As a secondary objective, we aimed to assess the methodological rigor employed in studies examining VEGF measurements from tissue and serum sources.

Methods

Literature searching

For initial searching, we searched the PubMed and Epistemonikos from February to April 2023. We included studies only limited to original research in human, published in the last 10 years. The search for studies in this systematic review used the search term “vascular endothelial growth factor” AND “hepatocellular carcinoma” AND “diagnosis” which resulted in total a 4115 studies. Subsequently, we identified duplications and screened titles and abstracts by using Rayyan – Intelligence Systematic Review tool (https://www.rayyan.ai). Study flowchart using the PRISMA 2020 guideline is presented in Figure 1.

Figure 1. PRISMA flow chart of study selection.

Modified from: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71.

For more information, visit: http://www.prisma-statement.org/.

Results and Discussion

A preliminary search in May 2023 using two electronic databases, PubMed and Epistemonikos, retrieved 4,115 articles. After removing 127 duplicate articles, we proceeded to review the titles and abstracts of the remaining 3,988 articles for preliminary screening. This process yielded 41 eligible articles for further analysis. An additional 32 articles were subsequently excluded because the required study outcome was not available. In total, nine studies were included in this systematic review for qualitative analysis. The search flowchart and selection methods for this systematic review were summarized in Figure 1 of the PRISMA 2020 flow diagram for systematic reviews.

Methodological quality

The quality of the included studies was evaluated using the Cochrane QUADAS Tool, which includes both QUADAS-2 and QUADAS-C assessments. Notably, more than half of the research was categorized as high risk in the domains of patient selection, index test, and flow and timing. However, in the domain of the reference standard, the studies generally exhibited a low risk of bias. Table 3 and Figure 2 provides detailed overview of the total risk of bias of all selected studies.

Table 3. Risk of bias assessments using QUADAS-2 method.

Study	Test	Risk of bias				Applicability concerns
		P	I	R	FT	P	I	R
Mukozu et al., 2013	VEGF	✓	✓	✓	?	✗	✓	✓
Lukito et al., 2014	VEGF	✗	?	✓	?	✓	✓	✓
Zhang W et al., 2014	VEGF	✗	?	✓	✓	✓	✓	✓
Yvamoto et al., 2015	VEGF	✗	✗	✓	?	✗	✓	✓
Sadik et al., 2019	VEGF	✗	?	?	?	✗	✓	?
Hamdy MN et al., 2020	VEGF	✗	?	?	✓	✓	✓	?
Alzamzamy et al., 2021	VEGF	✓	?	✓	?	✗	✓	✓
Zhu et al., 2022	VEGF	✓	?	✓	?	✓	✓	✓
Dala et al., 2023	VEGF	✗	?	✓	?	✗	✓	✓
Mukozu et al., 2013	AFP	✓	✓	✓	?	✗	✓	✓
Lukito et al., 2014	AFP	✗	?	✓	?	✓	✓	✓
Zhang W et al., 2014	KAI 1	✗	?	✓	✓	✓	✓	✓
Yvamoto et al., 2015	AFP	✗	✗	✓	?	✗	✓	✓
Sadik et al., 2019	AFP	✗	?	?	?	✗	✓	?
Hamdy MN et al., 2020	AFP	✗	?	?	✓	✓	✓	?
Alzamzamy et al., 2021	AFP	✓	?	✓	?	✗	✓	✓
Zhu et al., 2022	GPC3 and DCP	✓	?	✓	?	✓	✓	✓
Dala et al., 2023	AFP	✗	?	✓	?	✗	✓	✓
Mukozu et al., 2013	VEGF vs AFP	✓	✓	✓	✗
Lukito et al., 2014	VEGF vs AFP	✗	✗	✗	✗
Zhang W et al., 2014	VEGF vs KAI 1	✗	✗	✗	✗
Yvamoto et al., 2015	VEGF vs AFP	✗	✗	✗	✗
Sadik et al., 2019	VEGF vs AFP	✗	✗	✗	✗
Hamdy MN et al., 2020	VEGF vs AFP	✗	✗	✗	✗
Alzamzamy et al., 2021	VEGF vs AFP	✗	✗	✗	✗
Zhu et al., 2022	VEGF vs AFP	✗	✗	✗	✗
Dala et al., 2023	VEGF vs AFP	✗	✗	✗	✗

Figure 2. Summary of overall risk of bias (ROB) of selected studies.

Conclusions

For individuals without elevated AFP levels, particularly those considered normal, VEGF can serve as an alternative screening test for HCC, enabling the differentiation of this condition from other high-risk conditions like liver cirrhosis.

Ethics approval and consent to participate

Not applicable

Authors’ contributions

RM conceived the idea and formulated the research questions. RM, RH, MA, AN, and FM performed the literature searching, prepared the initial manuscript, and performed data analyses. AQ and RAY made critical revisions. AQ provided the submitted manuscript. RM and AQ reviewed and advised further revisions. All authors read and approved the final manuscript.

Consent for publication

Not applicable.