Systematic Review of Genetic Factors in the Etiology of Esophageal Squamous Cell Carcinoma in African Populations

Genome-wide association study of esophageal squamous cell cancer identifies shared and distinct risk variants in African and Chinese populations

Esophageal squamous cell carcinoma (ESCC) has a high disease burden in sub-Saharan Africa and has a very poor prognosis. Genome-wide association studies (GWASs) of ESCC in predominantly East Asian populations indicate a substantial genetic contribution to its etiology, but no genome-wide studies have been done in populations of African ancestry. Here, we report a GWAS in 1,686 African individuals with ESCC and 3,217 population-matched control individuals to investigate its genetic etiology. We identified a genome-wide-significant risk locus on chromosome 9 upstream of FAM120A (rs12379660, p = 4.58 × 10-8, odds ratio = 1.28, 95% confidence interval = 1.22-1.34), as well as a potential African-specific risk locus on chromosome 2 (rs142741123, p = 5.49 × 10-8) within MYO1B. FAM120A is a component of oxidative stress-induced survival signals, and the associated variants at the FAM120A locus co-localized with highly significant cis-eQTLs in FAM120AOS in both esophageal mucosa and esophageal muscularis tissue. A trans-ethnic meta-analysis was then performed with the African ESCC study and a Chinese ESCC study in a combined total of 3,699 ESCC-affected individuals and 5,918 control individuals, which identified three genome-wide-significant loci on chromosome 9 at FAM120A (rs12379660, pmeta = 9.36 × 10-10), chromosome 10 at PLCE1 (rs7099485, pmeta = 1.48 × 10-8), and chromosome 22 at CHEK2 (rs1033667, pmeta = 1.47 × 10-9). This indicates the existence of both shared and distinct genetic risk loci for ESCC in African and Asian populations. Our GWAS of ESCC conducted in a population of African ancestry indicates a substantial genetic contribution to ESCC risk in Africa.

A Genomic Analysis of Esophageal Squamous Cell Carcinoma in Eastern Africa

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) comprises 90% of all esophageal cancer cases globally and is the most common histology in low-resource settings. Eastern Africa has a disproportionately high incidence of ESCC.

METHODS

We describe the genomic profiles of 61 ESCC cases from Tanzania and compare them to profiles from an existing cohort of ESCC cases from Malawi. We also provide a comparison to ESCC tumors in The Cancer Genome Atlas (TCGA).

RESULTS

We observed substantial transcriptional overlap with other squamous histologies via comparison with TCGA PanCan dataset. DNA analysis revealed known mutational patterns, both genome-wide as well as in genes known to be commonly mutated in ESCC. TP53 mutations were the most common somatic mutation in tumors from both Tanzania and Malawi but were detected at lower frequencies than previously reported in ESCC cases from other settings. In a combined analysis, two unique transcriptional clusters were identified: a proliferative/epithelial cluster and an invasive/migrative/mesenchymal cluster. Mutational signature analysis of the Tanzanian cohort revealed common signatures associated with aging and cytidine deaminase activity (APOBEC) and an absence of signature 29, which was previously reported in the Malawi cohort.

CONCLUSIONS

This study defines the molecular characteristics of ESCC in Tanzania, and enriches the Eastern African dataset, with findings of overall similarities but also some heterogeneity across two unique sites.

IMPACT

Despite a high burden of ESCC in Eastern Africa, investigations into the genomics in this region are nascent. This represents the largest comprehensive genomic analysis ESCC from sub-Saharan Africa to date.

Environmental and life-style risk factors for esophageal squamous cell carcinoma in Africa: a systematic review and meta-analysis

BACKGROUND

The African Esophageal Squamous Cell Carcinoma (ESCC) corridor, which spans from Ethiopia down to South Africa, is an esophageal cancer hotspot. Disproportionately high incidence and mortality rates of esophageal cancer have been reported from this region. The aim of this study was to systematically assess the evidence on environmental and life-style risk factors associated with ESCC in African populations.

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and carried out a comprehensive search of all African published studies up to March 2023 using PubMed, Embase, Scopus, and African Index Medicus databases.

RESULTS

We identified 45 studies with measures of association [odds ratio (OR), relative risk (RR), and 95% confidence intervals (95%CI)], which reported on several environmental and lifestyle risk factors for ESCC in Africa. We performed a meta-analysis on 38 studies investigating tobacco, alcohol use, combined tobacco and alcohol use, polycyclic aromatic hydrocarbon exposure, hot food and beverages consumption (which served as a proxy for esophageal injury through exposure to high temperature), and poor oral health. We found significant associations between all the risk factors and ESCC development. Analysis of fruit and vegetable consumption showed a protective effect. Using population attributable fraction (PAF) analysis, we calculated the proportion of ESCC attributable to tobacco (18%), alcohol use (12%), combined tobacco and alcohol use (18%), polycyclic aromatic hydrocarbon exposure (12%), hot food and beverages intake (16%), poor oral health (37%), and fruit and vegetable consumption (-12%).

CONCLUSIONS

Tobacco smoking and alcohol consumption were the most studied risk factors overall. Areas where there is an emerging body of evidence include hot food and beverages and oral health. Concurrently, new avenues of research are also emerging in PAH exposure, and diet as risk factors. Our results point to a multifactorial etiology of ESCC in African populations with further evidence on prevention potential.

The contribution of smoking and smokeless tobacco to oesophageal squamous cell carcinoma risk in the African oesophageal cancer corridor: Results from the ESCCAPE multicentre case-control studies

Tobacco use is a well-established risk factor for oesophageal squamous cell carcinoma (ESCC) but the extent of its contribution to the disease burden in the African oesophageal cancer corridor has not been comprehensively elucidated, including by type of tobacco use. We investigated the contribution of tobacco use (smoking and smokeless) to ESCC in Tanzania, Malawi and Kenya. Hospital-based ESCC case-control studies were conducted in the three countries. Incident cases and controls were interviewed using a comprehensive questionnaire which included questions on tobacco smoking and smokeless tobacco use. Logistic regression models were used to estimate odds ratios (OR) and their 95% confidence intervals (CI) of ESCC associated with tobacco, adjusted for age, sex, alcohol use, religion, education and area of residence. One thousand two hundred seventy-nine cases and 1345 controls were recruited between August 5, 2013, and May 24, 2020. Ever-tobacco use was associated with increased ESCC risk in all countries: Tanzania (OR 3.09, 95%CI 1.83-5.23), and in Malawi (OR 2.45, 95%CI 1.80-3.33) and lesser in Kenya (OR 1.37, 95%CI 0.94-2.00). Exclusive smokeless tobacco use was positively associated with ESCC risk, in Tanzania, Malawi and Kenya combined (OR 1.92, 95%CI 1.26-2.92). ESCC risk increased with tobacco smoking intensity and duration of smoking. Tobacco use is an important risk factor of ESCC in Tanzania, Malawi and Kenya. Our study provides evidence that smoking and smokeless tobacco cessation are imperative in reducing ESCC risk.

A concise review towards defining the exposome of oesophageal cancer in sub-Saharan Africa

CONTEXT

Oesophageal cancer (EC) is among the common causes of illness and death among all cancers worldwide. Advanced EC has a poor prognosis, with worse outcomes observed in low-income settings. Oesophageal squamous cell carcinoma (ESCC) is the most common EC histology reported globally, with the highest ESCC incidence rates in the 'Asian Belt' and the African EC corridor. While the aetiology of ESCC is well-documented in the 'Asian belt', data for the African EC corridor and the entirety of sub-Saharan Africa (SSA) are fewer.

OBJECTIVE

To help address gaps in ESCC aetiology in SSA, we critically evaluated evidence of lifestyle, environmental, and epigenetic factors associated with ESCC risk and discussed prospects of defining ESCC exposome.

DATA INCLUSION

Unlimited English and non-English articles search were made on PubMed Central and Web of Science databases from January 1970 to August 2021. In total, we retrieved 999 articles and considered meta-analyses, case-control, and cohort studies. The quality of individual studies was assessed using the Newcastle-Ottawa scale.

DATA EXTRACTION

Details extracted include the year of publication, country of origin, sample size, comparators, outcomes, study subjects, and designs.

DATA ANALYSIS

Together, we assessed 13 case-control studies and two meta-analyses for the effect of lifestyle or environmental exposures on ESCC risk. Again, we evaluated seven case-control studies and one meta-analysis regarding the role of epigenetics in ESCC tumorigenesis.

RESULTS

In general, evidence of ESCC aetiology points to essential contributions of alcohol, tobacco, hot beverages, biomass fuel, and poor oral health/hygiene, although more precise risk characterisation remains necessary.

CONCLUSION

We conclude that ESCC in SSA is a multifactorial disease initiated by several external exposures that may induce aberrant epigenetic changes. The expanding aetiological research in this domain will be enhanced by evidence synthesis from classical and molecular epidemiological studies spanning the external and internal exposome.

Prognostic Function of Programmed Cell Death-Ligand 1 in Esophageal Squamous Cell Carcinoma Patients Without Preoperative Therapy: A Systematic Review and Meta-Analysis

Background

Studies investigating the correlation between the expression of programmed cell death-ligand 1 (PD-L1) and prognosis in patients with esophageal squamous cell carcinoma (ESCC) not receiving preoperative therapy have increased significantly, but conclusions remain inconclusive. Therefore, this study aimed to determine the association between clinical outcomes and expression of PD-L1 in ESCC patients without preoperative therapy.

Methods

We conducted a comprehensive literature search using four databases up to May 2020. Quality assessment was carried out according to the Newcastle-Ottawa Quality Assessment Scale (NOS). Hazard ratios (HRs) were used to analyze the association between PD-L1 expression with prognosis. Furthermore, we evaluated the correlation between PD-L1 and clinicopathological characteristics using odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Twenty studies (19 publications) comprising 3,677 patients were included in this meta-analysis. We found that the expression of PD-L1 was not related to overall survival (OS, HR: 1.16, 95% CI: 0.94-1.42, p = 0.16) or disease-free survival (DFS, HR: 0.85, 95% CI: 0.66-1.10, p = 0.21) in ESCC. Furthermore, although PD-L1 expression was not significantly associated with sex, degree of differentiation, TNM stage, T stage, lymph node status, smoking, or alcohol use, the merged OR demonstrated that the expression of PD-L1 was higher in older patients compared to younger patients (OR: 1.40, 95% CI: 1.07-1.83, p = 0.01). No obvious publication bias was observed.

Conclusions

Our present study illustrated that PD-L1 expression was not related to poor prognosis of ESCC patients not receiving preoperative therapy, albeit the association only showed a tendency for statistical significance. Notably, PD-L1 expression showed a significant association with age. This meta-analysis had several limitations; therefore, our results need to be verified through further large-scale and prospective studies.

Microbiome and Cancers of the Esophagus: A Review

Esophageal cancer (EC) is an aggressive malignant disease ranking amongst the leading causes of cancer deaths in the world. The two main histologic subtypes, esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC), have distinct geographic and temporal patterns and risk factor profiles. Despite decades of research, the factors underlying these geo-temporal patterns are still not fully understood. The human microbiome has recently been implicated in various health conditions and disease, and it is possible that the microbiome may play an important role in the etiology of EC. Although studies of the microbiome and EC are still in their early stages, we review our current understanding of the potential links between ESCC, EAC, and bacterial communities in the oral cavity and esophagus. We also provide a summary of the epidemiology of EC and highlight some key challenges and future directions.

[N-aсetyltransferase (NAT2) gene polymorphism and gene network analysis]

To search for new targets of therapy, it is necessary to reconstruct the gene network of the disease, and identify the interaction of genes, proteins, and drug compounds. Using the online bioinformatics tools we have analyzed the current data set related to the metabolism of xenobiotics, mediated by the N-acetyltransferase 2 (NAT2) gene. The study of allelic polymorphism of the NAT2 gene has a prognostic value, allowing to determine the risk of a number of oncological diseases, the degree of increased risk due to smoking and exposure to chemical carcinogens, including drugs. The aim of this study was to determine the frequencies of two important "slow" variants of the NAT2 gene (NAT2*5, rs1801280 and NAT2*7, rs1799931), which significantly affected the rate of xenobiotic acetylation among the indigenous Nenets population of Northern Siberia. The obtained frequencies of polymorphic variants among the Nenets occupy an intermediate value between those for Europeans and Asians, which might indicate specific features of adaptation. We present a model of the distribution of two polymorphic variants of the NAT2 gene involved in the biotransformation of xenobiotics to study the characteristics of their metabolism in the indigenous inhabitants of Yamal.

Mutational analysis of apoptotic genes in familial aggregation of hematological malignancies

INTRODUCTION

Apoptosis deregulation have been associated to tumorigenesis process and was highlighted as a prominent hallmark of cancer. Several mutations have been reported in several forms of Blood cancer. However, it has never been investigated in familial aggregations of hematological malignancies.

METHODS

In this study, we performed a mutational analysis by sequencing the entire coding regions in four key apoptotic genes FAS, FASLG, CASP8 and CASP10 in 92 independent families belonging to French and Tunisian populations and diagnosed with several forms of familial hematological malignancies.

RESULTS

We report 15 genetic variations among which 7 were previously reported in several form of cancers and have a potential effect on gene expression. Particularly, the CASP8 variants p.Asp302His and p.Lys337Lys were detected in 15% and 10% of our group of patients respectively and were previously reported in association to breast cancer and to breast cancer susceptibility.

DISCUSSION

In this study, we do not report the underlining deleterious mutations in familial hematological malignancies, but we describe some variants with potential risk of developing blood cancer. To gain further insights on the association between apoptosis pathway deregulation and familial hematological malignancies, more apoptotic genes should be investigated.

Associations of interleukin-4 and interleukin-4 receptor loci with esophageal squamous cell carcinoma susceptibility

Some functional polymorphisms in immune-regulating genes could affect the development of esophageal squamous cell carcinoma (ESCC). We enrolled 721 patients with ESCC and 1,208 healthy controls to explore the roles of rs2227282 (C > G) and rs2243283 (C > G) loci in the interleukin-4 (IL4) gene and rs1801275 loci in the interleukin-4 receptor (IL4R) gene for the occurrence of ESCC. As for IL4, the single nucleotide polymorphism rs2227282 (C > G) conferred an overall decreased risk for ESCC (adjusted P = 0.005, power = 0.816 in GG vs. CC genetic models). A stratification analysis of IL4 rs2227282 (C > G) and rs2243283 (C > G) and IL4R rs1801275 (A > G) loci with the ESCC risk revealed that the IL4 rs2243283 (C > G) polymorphism was a protective factor for the susceptibility to ESCC in some subgroups (women: power = 0.932 in CG vs. CC and 0.956 in CG/GG vs. CC; subjects aged ≥63 years: power = 0.844 in CG/GG vs. CC; never-smokers: power = 0.893 in CG vs. CC and 0.882 in CG/GG vs. CC; never-drinkers: power = 0.904 in CG vs. CC and 0.862 in CG/GG vs. CC). We also investigated the association of IL4 rs2227282 and rs2243283 and IL4R rs1801275 loci with the lymph node status. However, a null relationship was found. In conclusion, the present study highlighted that IL4 rs2227282 (C > G) and rs2243283 (C > G) loci are protective factors for the occurrence of ESCC.

Understanding Esophageal Cancer: The Challenges and Opportunities for the Next Decade

Esophageal cancer (EC) is the seventh most common cancer worldwide with over 570,000 new cases annually. In China, the incidence of EC is particularly high where approximately 90% of cases are defined as esophageal squamous cell carcinoma (ESCC). Although various risk factors have been identified, the knowledge of genetic drivers for ESCC is still limited due to high mutational loading of the cancer and lack of appropriate EC models, resulting in inadequate treatment choices for EC patients. Currently, surgery, chemotherapy, radiation, and limited targeted therapy options can only bring dismal survival advantages; thus, the prognosis for ESCC is very poor. However, cancer immunotherapy has unleashed a new era of cancer treatment with extraordinary therapeutic benefits for cancer patients, including EC patients. This review discusses the latest understanding of the risk factors and clinical rational for EC treatment and provides accumulated information, which describes the ongoing development of immunotherapy for EC with a specific emphasis on ESCC, the most prevalent EC subtype in the Chinese population.