A comparison between alpha-fetoprotein and p53 antibodies in the diagnosis of hepatocellular carcinoma

Immunodiagnostic Biomarkers for Hepatocellular Carcinoma (HCC): The First Step in Detection and Treatment

Hepatocellular carcinoma (HCC) exerts huge effects on the health burden of the world because of its high mortality and poor prognosis. HCC is often clinically detected late in patients. If HCC could be detected and treated earlier, the survival rate of patients will be greatly improved. Therefore, identifying specific biomarkers is urgent and important for HCC. The liver is also recognized as an immune organ. The occurrence of HCC is related to exacerbation of immune tolerance and/or immunosurveillance escape. The host immune system plays an important role in the recognition and targeting of tumor cells in cancer immunotherapy, as can be seen from the clinical success of immune checkpoint inhibitors and chimeric antigen receptor (CAR) T cells. Thus, there is a pressing medical need to discover immunodiagnostic biomarkers specific to HCC for understanding the pathological mechanisms of HCC, especially for immunotherapy targets. We have reviewed the existing literature to summarize the immunodiagnostic markers of HCC, including autoantibodies against tumor-associated antigens (TAAs) and exosomes, to provide new insights into HCC and early detection of this deadly cancer.

Abdominal ultrasound and alpha-foetoprotein for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma (HCC) occurs mostly in people with chronic liver disease and ranks sixth in terms of global instances of cancer, and fourth in terms of cancer deaths for men. Despite that abdominal ultrasound (US) is used as an initial test to exclude the presence of focal liver lesions and serum alpha-foetoprotein (AFP) measurement may raise suspicion of HCC occurrence, further testing to confirm diagnosis as well as staging of HCC is required. Current guidelines recommend surveillance programme using US, with or without AFP, to detect HCC in high-risk populations despite the lack of clear benefits on overall survival. Assessing the diagnostic accuracy of US and AFP may clarify whether the absence of benefit in surveillance programmes could be related to under-diagnosis. Therefore, assessment of the accuracy of these two tests for diagnosing HCC in people with chronic liver disease, not included in surveillance programmes, is needed.

OBJECTIVES

Primary: the diagnostic accuracy of US and AFP, alone or in combination, for the diagnosis of HCC of any size and at any stage in adults with chronic liver disease, either in a surveillance programme or in a clinical setting. Secondary: to assess the diagnostic accuracy of abdominal US and AFP, alone or in combination, for the diagnosis of resectable HCC; to compare the diagnostic accuracy of the individual tests versus the combination of both tests; to investigate sources of heterogeneity in the results.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Hepato-Biliary Group Diagnostic-Test-Accuracy Studies Register, Cochrane Library, MEDLINE, Embase, LILACS, Science Citation Index Expanded, until 5 June 2020. We applied no language or document-type restrictions.

SELECTION CRITERIA

Studies assessing the diagnostic accuracy of US and AFP, independently or in combination, for the diagnosis of HCC in adults with chronic liver disease, with cross-sectional and case-control designs, using one of the acceptable reference standards, such as pathology of the explanted liver, histology of resected or biopsied focal liver lesion, or typical characteristics on computed tomography, or magnetic resonance imaging, all with a six-months follow-up.

DATA COLLECTION AND ANALYSIS

We independently screened studies, extracted data, and assessed the risk of bias and applicability concerns, using the QUADAS-2 checklist. We presented the results of sensitivity and specificity, using paired forest-plots, and tabulated the results. We used a hierarchical meta-analysis model where appropriate. We presented uncertainty of the accuracy estimates using 95% confidence intervals (CIs). We double-checked all data extractions and analyses.

MAIN RESULTS

We included 373 studies. The index-test was AFP (326 studies, 144,570 participants); US (39 studies, 18,792 participants); and a combination of AFP and US (eight studies, 5454 participants). We judged at high-risk of bias all but one study. Most studies used different reference standards, often inappropriate to exclude the presence of the target condition, and the time-interval between the index test and the reference standard was rarely defined. Most studies with AFP had a case-control design. We also had major concerns for the applicability due to the characteristics of the participants. As the primary studies with AFP used different cut-offs, we performed a meta-analysis using the hierarchical-summary-receiver-operating-characteristic model, then we carried out two meta-analyses including only studies reporting the most used cut-offs: around 20 ng/mL or 200 ng/mL. AFP cut-off 20 ng/mL: for HCC (147 studies) sensitivity 60% (95% CI 58% to 62%), specificity 84% (95% CI 82% to 86%); for resectable HCC (six studies) sensitivity 65% (95% CI 62% to 68%), specificity 80% (95% CI 59% to 91%). AFP cut-off 200 ng/mL: for HCC (56 studies) sensitivity 36% (95% CI 31% to 41%), specificity 99% (95% CI 98% to 99%); for resectable HCC (two studies) one with sensitivity 4% (95% CI 0% to 19%), specificity 100% (95% CI 96% to 100%), and one with sensitivity 8% (95% CI 3% to 18%), specificity 100% (95% CI 97% to 100%). US: for HCC (39 studies) sensitivity 72% (95% CI 63% to 79%), specificity 94% (95% CI 91% to 96%); for resectable HCC (seven studies) sensitivity 53% (95% CI 38% to 67%), specificity 96% (95% CI 94% to 97%). Combination of AFP (cut-off of 20 ng/mL) and US: for HCC (six studies) sensitivity 96% (95% CI 88% to 98%), specificity 85% (95% CI 73% to 93%); for resectable HCC (two studies) one with sensitivity 89% (95% CI 73% to 97%), specificity of 83% (95% CI 76% to 88%), and one with sensitivity 79% (95% CI 54% to 94%), specificity 87% (95% CI 79% to 94%). The observed heterogeneity in the results remains mostly unexplained, and only in part referable to different cut-offs or settings (surveillance programme compared to clinical series). The sensitivity analyses, excluding studies published as abstracts, or with case-control design, showed no variation in the results. We compared the accuracy obtained from studies with AFP (cut-off around 20 ng/mL) and US: a direct comparison in 11 studies (6674 participants) showed a higher sensitivity of US (81%, 95% CI 66% to 90%) versus AFP (64%, 95% CI 56% to 71%) with similar specificity: US 92% (95% CI 83% to 97%) versus AFP 89% (95% CI 79% to 94%). A direct comparison of six studies (5044 participants) showed a higher sensitivity (96%, 95% CI 88% to 98%) of the combination of AFP and US versus US (76%, 95% CI 56% to 89%) with similar specificity: AFP and US 85% (95% CI 73% to 92%) versus US 93% (95% CI 80% to 98%).

AUTHORS' CONCLUSIONS

In the clinical pathway for the diagnosis of HCC in adults, AFP and US, singularly or in combination, have the role of triage-tests. We found that using AFP, with 20 ng/mL as a cut-off, about 40% of HCC occurrences would be missed, and with US alone, more than a quarter. The combination of the two tests showed the highest sensitivity and less than 5% of HCC occurrences would be missed with about 15% of false-positive results. The uncertainty resulting from the poor study quality and the heterogeneity of included studies limit our ability to confidently draw conclusions based on our results.

Molecular background of alpha-fetoprotein in liver cancer cells as revealed by global RNA expression analysis

alpha-Fetoprotein (AFP) is considered to be a diagnostic and prognostic biomarker in hepatocellular carcinoma (HCC). However, the role of AFP in the development of HCC is presently obscure. We hypothesized that a certain set of genes is expressed in a manner coordinate with AFP, and that these genes essentially contribute to the malignant characteristics of AFP-producing HCC. To address this hypothesis, we carried out global mRNA expression analysis of 21 liver cancer cell lines that produce varying levels of AFP. We identified 213 genes whose mRNA expression levels were significantly correlated with that of AFP (P < 0.0001). These included liver-specific transcription factors for AFP and other albumin family genes. Eighteen HCC-associated genes and 11 genes associated with malignancies other than HCC showed significant correlations with AFP production levels. Genes involved in lipid catabolism, blood coagulation, iron metabolism, angiogenesis, and the Wnt and mitogen-activated protein kinase pathways were also identified. Text data mining revealed that participation in the transcription factor network could explain the connection between 78 of the identified genes. Glypican 3, which is a component of the Wnt pathway and contributes to HCC development, had the fifth highest correlation coefficient with AFP. Reactivity to specific antibodies confirmed the significant correlation between AFP and glypican 3 expression in HCC tissues. These observations suggest that AFP-producing liver cancer cells may have a unique molecular background consisting of cancer-associated genes. From this genome-wide association study, novel aspects of the molecular background of AFP were revealed, and thus may lead to the identification of novel biomarker candidates.

The clinical significance of autoantibodies in gastrointestinal malignancies: an overview

Autoimmunity can be associated with cancer and one of the forms of its expression is the development of antibodies to autologous cellular antigens. The types of cellular proteins which induce autoantibody responses in gastrointestinal malignancies are quite varied and include cellular proteins encoded by mutated normal genes (p53), cellular proteins that are overexpressed and/or aberrantly expressed in malignant tissues (carcinoembryonic antigen), inhibitors of apoptosis (survivin and livin), major components of mucus (mucins), surface receptors of apoptosis (Fas) and nuclear-restricted proteins (double-stranded DNA, single-stranded DNA and Sm family proteins). In the past few years, due to the great clinical interest and the advancement in detection techniques, the above list has grown significantly and a large number of cancer-related antigens, which trigger a specific humoral immune response to the host, have also been identified. The authors review the autoantibodies associated with gastrointestinal malignancies and their clinical implications.

Serum insulin-like growth factor-II as a serologic marker of small hepatocellular carcinoma

OBJECTIVE

Alpha-fetoprotein (AFP) is not a useful tumor marker for diagnosis of small hepatocellular carcinoma (HCC). There is over-expression of insulin-like growth factor (IGF)-II in HCC tissue. This study investigates the diagnostic application of IGF-II in small HCC.

MATERIAL AND METHODS

Serum levels of IGF-II and AFP were determined in 41 patients with small cirrhotic HCC (< or = 3 cm), 41 sex- and age-matched patients with cirrhosis alone (LC), and 41 healthy adults. The optimal cut-off values for diagnosing HCC were determined with receiver operating characteristics (ROC) curve.

RESULTS

Both IGF-II and AFP levels in HCC were higher than those in LC patients or controls (each p = 0.0001). The IGF-II levels in LC patients were lower than those in controls (p = 0.001). In HCC patients, multivariate analysis indicated that that both IGF-II (odds ratio, 4.54; 95% confidence interval, 2.15-9.55; p = 0.0001) and AFP (odds ratio, 1.05; 95% confidence interval, 1.01-1.08; p = 0.003) were found to be associated with an increased risk of presence of HCC. The optimal cut-off values of IGF-II (4.1 mg/g prealbumin) and AFP (50 ng/ml) were determined with ROC curves. The sensitivity, specificity, and diagnostic accuracy values for IGF-II were 63%, 90%, and 70%, respectively. Those for AFP were 44%, 95%, and 70%, respectively. Determination of both markers in parallel significantly increase the diagnostic accuracy (88%) and sensitivity (80%), with a high specificity (90%).

CONCLUSIONS

Serum IGF-II level can be used as an independent serologic marker or a complementary tumor marker to AFP for diagnosis of small HCC.