Esophageal Cancer in Golestan Province, Iran: A Review of Genetic Susceptibility and Environmental Risk Factors

Prediction of five-year survival among esophageal cancer patients using machine learning

Background and aim

Considering the silent progression of esophageal cancer, the survival prediction of this disease is crucial in enhancing the quality of life of these patients globally. So far, no prediction solution has been introduced for the survival of EC in Iran based on the machine learning approach. So, this study aims to develop a prediction model for the five-year survival of EC based on the ML approach to promote clinical outcomes and various treatment and preventive plans.

Material and methods

In this retrospective study, we investigated the 1656 cases of survived and non-survived EC patients belonging to Imam Khomeini Hospital in Sari City from 2013 to 2020. The multivariable regression analysis was used to select the best predictors of five-year survival. We leveraged random forest, eXtreme Gradient Boosting, support vector machine, artificial neural networks, Bayesian networks, J-48 decision tree, and K-nearest neighborhood to develop the prediction models. To get the best model for predicting the five-year survival of EC, we compared them using the area under the receiver operator characteristics.

Results

The age at diagnosis, body mass index, smoking, obstruction, dysphagia, weight loss, lymphadenopathy, chemotherapy, radiotherapy, family history of EC, tumor stage, type of appearance, histological type, grade of differentiation, tumor location, tumor size, lymphatic invasion, vascular invasion, and platelet albumin ratio were considered as the best predictors associated with the five-year survival of EC based on the regression analysis. In this respect, the random forest with the area under the receiver operator characteristics of 0.95 was identified as a superior model.

Conclusion

The experimental results of the current study showed that the random forest could have a significant role in enhancing the quality of care in EC patients by increasing the effectiveness of follow-up and treatment measures introduced by care providers.

Journey Through Words: Exploring Esophageal Cancer in Literature

Esophageal cancer is a significant global health challenge, characterized by its aggressive nature and high mortality rates. The disease disproportionately affects males and ranks among the leading causes of cancer-related deaths worldwide. Alarming projections indicate that the prevalence of esophageal cancer is expected to surge by approximately 140% by the year 2025. This trend starkly contrasts with the anticipated decline in incidence observed for many other types of cancers. The cancer manifests primarily in two major subtypes: esophageal squamous cell carcinoma and adenocarcinoma, each with distinct epidemiological and biological characteristics. This review provides an in-depth exploration of the risk factors, anatomy, clinical presentation, diagnosis, staging, prognosis, treatment modalities, recurrence, advancements, and emerging therapies in esophageal cancer. Additionally, preventive and early detection strategies are discussed, focusing on primary, secondary, and tertiary prevention approaches. A comprehensive understanding of esophageal cancer is vital for formulating effective management strategies and improving patient outcomes.

Human biomonitoring and reference values of urinary 1-hydroxypyrene among Iranian adults population

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important environmental pollutants. Urinary concentrations of 1-hydropyren metabolites of PAHs have been used as biomarkers of these chemicals' exposure in humans. This cross-sectional study was conducted on 468 healthy Iranian adults over 25 years old and non-smokers in six provinces who were selected based on the clustering method. Fasting urine sampling and body composition and demographic measurements were performed. Urine samples were analyzed by GC-MS. The analysis included descriptive statistics and analytical statistics using multiple linear regression by Python software. 1-Hydroxypyrene was found in 100% of samples, and the mean (Reference Value 95%) concentration of 1-hydroxypyrene was 6.12 (RV 95%: 20) μg/L and 5.95 (21) μg/gcrt. There was a direct relationship between the amount of body composition (body fat, visceral fat), BMI, and age with the urinary concentrations of 1-hydropyren metabolites, and this relationship was significant for BMI with urinary concentrations of 1-hydropyren metabolites (P = 0.045). The amount of 1-hydroxypyrene in healthy Iranian adults has been higher than in similar studies in other countries. These results provide helpful information regarding the exposure of Iranian adults to 1-hydroxypyrene, and these data can be used to supplement the national reference values of human biomonitoring for the interpretation of biomonitoring results.

Bac to Bac System Efficiency for Preparing HPV Type 16 Virus-Like Particle Vaccine

Today, the human papillomavirus (HPV) L1 protein is the main target in the construction of prophylactic HPV vaccines. The production of virus-like particles (VLPs) that closely resemble the natural structure of the HPV16 virus and induce high levels of virus-neutralizing antibodies in animals and humans is facilitated by the expression of HPV16-L1 protein in eukaryotic cells. The Bac-to-Bac system has been previously used to produce high levels of recombinant proteins. In this study, we utilized this expression system to generate HPV16-L1 VLPs in Spodoptra frugipedra (Sf9) insect cells. The wild-type L1 gene of papillomavirus type 16 was selected from Gene Bank and placed in bacmid structure after codon optimization using pFast Bac vector. The recombinant baculovirus containing HPV-16/L1 gene was then provided using the Bac-to-Bac system. It should be mentioned that the vector was transfected into the Sf9 cell. The cells were then lysed and the expression of L1 protein was revealed by SDS-PAGE and confirmed by Western Blot. The L1 purification was performed through Ni-NTA chromatography. The VLP formation of papillomavirus L1 protein was visualized by transmission electron microscopy. The expressed recombinant L1 was ~60 KD on SDS-PAGE which was identified in western blot by a specific anti-L1 monoclonal antibody. The electron microscopy confirmed the assembly of VLPs. Results of this study showed that the production of this protein at the industrial level can be optimized using a baculovirus/Sf9 system. The characteristics and advantages of this system are promising and it is a suitable candidate for protein synthesis.

The incidence of oral cavity cancer in Iran: A systematic review and meta-analysis

BACKGROUND AND AIMS

Oral cancer is now a top priority for non-communicable illnesses and universal health care plans, according to the WHO. There is no general estimate of the incidence of oral cavity cancer in Iran, despite multiple investigations. The purpose of this study is to evaluate the age-standardized incidence rate (ASR) of oral cavity cancers in Iran.

METHOD

In accordance with the MOOSE (Meta-analyses of Observational Studies in Epidemiology) Checklist recommendations, this systematic review was conducted. PubMed/MEDLINE, Web of Science, ScienceDirect, Embase, Scopus, ProQuest, and Google Scholar were used as the international databases for the systematic literature search, while SID (Scientific Information Database), Magiran and element were used as the Iranian databases. The heterogeneity of the research will be evaluated by means of the inverse variance and Cochran Q tests, along with random-effect models. It was determined what caused the heterogeneity using a meta-regression model. By eliminating experiments one at a time, sensitivity analysis was used. The meta-analysis was corrected utilizing the Trim-and-fill method due to the identification of noteworthy publication bias via the Egger's test and asymmetry of the funnel plot.

RESULTS

This research incorporated a total of 22 journal articles. The pooled ASR of oral cavity cancer for males and females was estimated at 1.96 (95% CI: 1.65-2.26) (Q statistic = 1118.09, df = 25, p < .0001, I²  = 97.8%), and 1.46 (95% CI: 1.14-1.77) (Q statistic = 2576.99, df = 26, p < .0001, I²  = 99.0%), respectively. According to the funnel plots and Egger's test, there is no evidence of publication bias in studies reporting on males (bias = 1.3220, 95% CI: -3.9571, 6.6012, p = .610), but for ASR in females, Egger's test was significant (bias = -7.6366, 95% CI: 2.2141, 13.05904, p = .008). Based on Trim-and-fill methods, overall ASR corrected in females was estimated to be 1.36 (95% CI: 1.05%-1.66%).

CONCLUSION

Iran's oral cavity cancer incidence was lower than the global average, but owing to variables including an aging population, a rise in life expectancy, and exposure to risk factors like smoking, we anticipate an increasing trend.

Toxic mechanisms of cadmium and exposure as a risk factor for oral and gastrointestinal carcinomas

Incidence and mortality rates of gastrointestinal (GI) and oral cancers are among the highest in the world, compared to other cancers. GI cancers include esophageal, gastric, colon, rectal, liver, and pancreatic cancers, with colorectal cancer being the most common. Oral cancer, which is included in the head and neck cancers category, is one of the most important causes of death in India. Cadmium (Cd) is a toxic element affecting humans and the environment, which has both natural and anthropogenic sources. Generally, water, soil, air, and food supplies are reported as some sources of Cd. It accumulates in organs, particularly in the kidneys and liver. Exposure to cadmium is associated with different types of health risks such as kidney dysfunction, cardiovascular disease, reproductive dysfunction, diabetes, cerebral infarction, and neurotoxic effects (Parkinson's disease (PD) and Alzheimer's disease (AD)). Exposure to Cd is also associated with various cancers, including lung, kidney, liver, stomach, hematopoietic system, gynecologic and breast cancer. In the present study, we have provided and summarized the association of Cd exposure with oral and GI cancers.

Meat consumption and risk of esophageal and gastric cancer in the Golestan Cohort Study, Iran

Red meat and processed meat are associated with some gastrointestinal cancers. Our study aims to investigate the association of different meat types with esophageal and gastric cancer (EC, GC) in a high-risk population. The Golestan Cohort Study (GCS) is a population-based cohort of 50 045 individuals aged 40 to 75 from northeast Iran. Detailed data on different exposures were collected using validated questionnaires. We considered quintiles of meat consumption, using grams and density (g/1000 kcal/day). We calculated intake of red, processed, organ and white meat, as well as total red meat, including the first three. We used proportional hazards regression models to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for the association between meat types and cancer. During 12 years of follow-up, out of 49 585 participants (57.4% women), 369 developed EC (48.2% women) and 368 developed GC (27.5% women), including 309 esophageal squamous cell, 20 esophageal adenocarcinomas, 216 cardia and 95 non-cardia GC. No association was found for EC except for red meat among females (HR for one quintile increase 1.13, 95% CI = 1.00-1.27). The risk of GC increased for intake of total red meat (HR 1.08, 95% CI = 1.00-1.17) and red meat separately (HR 1.09, 95% CI = 1.00-1.18). The HR for red meat and non-cardia GC was 1.23 (95% CI = 1.02-1.48). No associations were observed for other types of meat. In conclusion, in this high-risk population red meat intake is associated with GC, but not EC, suggesting a substantial role of this modifiable factor in determining the burden of GC.

Application Value of the Diagnosis during Early Carcinoma of Upper Digestive Tract Based on Optical Enhanced Endoscopic Technique

Objective. The diagnostic value of optical enhanced endoscopy in early cancer of upper digestive tract was studied by comparing the disease accuracy, tumor type, invasion, and various surgical indicators between the two groups. Methods. 188 patients with early upper gastrointestinal cancer treated in our hospital from January 2020 to February 2021 were selected as the research objects. The patients were randomly divided into the observation group and control group with 94 cases in each group. Results. The accuracy of early detection of early carcinoma of upper digestive tract in the observation group was 94.68% and that in the control group was 76.60%. The accuracy of the observation group was significantly higher than that in the control group, with statistical significance ( $P<0.05$ ). In the observation group, 36 cases of early gastric cancer, 28 cases of early esophageal cancer, and 30 cases of early colorectal cancer were detected; 25 cases of early gastric cancer, 19 cases of early esophageal cancer, and 28 cases of early colorectal cancer were detected; 26 cases of early carcinoma of upper digestive tract infiltration were detected; and 68 cases were not detected, and the detection rate was 27.66%, which was higher than 9.57% in the control group, and the difference was statistically significant ( $P<0.05$ ). After different methods of treatment, no death occurred in all patients. Except for the operation time, the surgical indexes of the observation group were better than the control group, the difference was statistically significant ( $P<0.05$ ). Conclusion. Optical enhanced endoscopic technique had obvious effect in the diagnosis of patients with early cancer of upper digestive tract, it was helpful to improve the clinical detection rate of early carcinoma of upper digestive tract and had certain diagnostic ability for the invasion depth of early cancer of high upper gastrointestinal tract, which was conducive to the detection of clinical invasion lesions and had high clinical promotion and application value.

The lag effect of exposure to PM2.5 on esophageal cancer in urban-rural areas across China

Exposure to PM_2.5 pollution is a significant health concern and increases risks for cancers in China. However, the studies regarding the effect of PM_2.5 and esophageal cancer incidence (ECI) among urban-rural areas are limited. In this study, we examined the sex- and area-specific association between exposure to PM_2.5 and ECI, as well as explored the corresponding lag effects on ECI using a geographical weighted Poisson regression. We found significantly positive effect on ECI for males and females in different models, with the greatest increase of 1.44% (95% CI: 1.30%, 1.59%) and 2.42% (95% CI: 2.17%, 2.66%) in per 10 ug/m³ increase of PM_2.5 for males and females at single year lag7 and lag4 after all covariates controlled, respectively. We also found that the long-term effect of PM_2.5 on ECI was relatively stable at all moving average year lags. Moreover, rural areas had higher ECI risks for males (0.17%) and females (0.64%) with longer lag period than urban areas. In addition, higher risks for both sexes appeared in north, northwestern, and east China. The findings indicated that long-term exposure to PM_2.5 was significantly associated with increased risks for ECI, which reinforce a comprehensive understanding for ECI related to PM_2.5.

Ten-year data analysis of digestive system malignancies in Babol, North of Iran: 2008-2017

BACKGROUND

Unlike some regions of the world where digestive system cancers are not considered as important health problems, these neoplasms are among the most common malignancies in the northern region of Iran.

METHODS

This observational analytical study was carried out based on data collected by the Cancer Registration Center affiliated to the Vice Chancellery for Health of Babol University of Medical Sciences, North of Iran, during 2008-2017. Crude incidence rate (CR), and age-standardized incidence rate (ASR) have been calculated for different GI cancers, based on the primary involved site; and have been compared in different years, patients' age, gender and place of residence.

RESULTS

Totally, 4332 records were related to digestive system cancers. Mean age of patients was 63.48±14.73 years; men (2743; 63.3%) were more affected than women (1589; 36.7%) (p<0.001). The most incident malignancies of digestive system were from stomach, colorectal and esophagus in men; and colorectal, stomach and esophagus in women, respectively. These three cancers accounted for 3725 (85.98%) of total GI malignancies. The mean age of patients in various types of GI cancers was statistically different (p<0.001). Age- standardized incidence rate showed different values in different years; from 521.40 (95% CI: 462.79-580.00) in year 2016 to 1834.33 (95% CI: 1637.36-2031.29) in year 2008.

CONCLUSION

Gastric, esophageal and colorectal cancers were the most prevalent digestive system malignancies in Babol, North of Iran, and accounted for about 86% of all GI tract cancers. A considerable variation has been found in incident gastrointestinal cancers in different years.

Esophageal squamous cell cancer in Plummer-Vinson syndrome: Is lichen planus a missing link?

This retrospective study analyzed the occurrence of esophageal squamous cell cancer (ESCC) in a cohort of patients with Plummer-Vinson syndrome (PVS) and mucosal lichen planus (LP). ESCC occurred in 6.2% cases of PVS, more than half of whom had associated oral LP. Mucosal LP and PVS together may increase the predisposition to ESCC.

Investigations concerning the impact of consumption of hot beverages on acute cytotoxic and genotoxic effects in oral mucosa cells

Consumption of very hot beverages and foods increases the incidence of oral and esophageal cancer but the mechanisms are not known and the critical temperature is not well defined. We realized a study with exfoliated cells from the oral cavity of individuals (n = 73) that live in an area in Iran which has the highest incidence of EC worldwide. Consumption of beverages at very high temperatures is a characteristic feature of this population. We analyzed biomarkers which are (i) indicative for genetic instability (micronuclei that are formed as a consequence of chromosomal damage, nuclear buds which are a consequence of gene amplifications and binucleated cells which reflect mitotic disturbances), (ii) markers that reflect cytotoxic effects (condensed chromatin, karyorrhectic, karyolitic and pyknotic cells), (iii) furthermore, we determined the number of basal cells which is indicative for the regenerative capacity of the buccal mucosa. The impact of the drinking temperature on the frequencies of these parameters was monitored with thermometers. We found no evidence for induction of genetic damage but an increase of the cytotoxic effects with the temperature was evident. This effect was paralleled by an increase of the cell division rate of the mucosa which was observed when the temperature exceeded 60 °C. Our findings indicate that cancer in the upper digestive tract in drinkers of very hot beverages is not caused by damage of the genetic material but by an increase of the cell division rate as a consequence of cytotoxic effects which take place at temperatures over 60 °C. It is known from earlier experiments with rodents that increased cell divisions lead to tumor promotion in the esophagus. Our findings provide a mechanistic explanation and indicate that increased cancer risks can be expected when the drinking temperature of beverages exceeds 60 °C.

Contributing factors common to COVID‑19 and gastrointestinal cancer

The devastating complications of coronavirus disease 2019 (COVID-19) result from the dysfunctional immune response of an individual following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events, ultimately leading to COVID-19. The authors have previously identified a number of contributing factors (CFs) common to myriad chronic diseases. Based on these observations, it was hypothesized that there may be a significant overlap between CFs associated with COVID-19 and gastrointestinal cancer (GIC). Thus, in the present study, a streamlined dot-product approach was used initially to identify potential CFs that affect COVID-19 and GIC directly (i.e., the simultaneous occurrence of CFs and disease in the same article). The nascent character of the COVID-19 core literature (~1-year-old) did not allow sufficient time for the direct effects of numerous CFs on COVID-19 to emerge from laboratory experiments and epidemiological studies. Therefore, a literature-related discovery approach was used to augment the COVID-19 core literature-based ‘direct impact’ CFs with discovery-based ‘indirect impact’ CFs [CFs were identified in the non-COVID-19 biomedical literature that had the same biomarker impact pattern (e.g., hyperinflammation, hypercoagulation, hypoxia, etc.) as was shown in the COVID-19 literature]. Approximately 2,250 candidate direct impact CFs in common between GIC and COVID-19 were identified, albeit some being variants of the same concept. As commonality proof of concept, 75 potential CFs that appeared promising were selected, and 63 overlapping COVID-19/GIC potential/candidate CFs were validated with biological plausibility. In total, 42 of the 63 were overlapping direct impact COVID-19/GIC CFs, and the remaining 21 were candidate GIC CFs that overlapped with indirect impact COVID-19 CFs. On the whole, the present study demonstrates that COVID-19 and GIC share a number of common risk/CFs, including behaviors and toxic exposures, that impair immune function. A key component of immune system health is the removal of those factors that contribute to immune system dysfunction in the first place. This requires a paradigm shift from traditional Western medicine, which often focuses on treatment, rather than prevention.

Association of Epstein–Barr Virus and Cytomegalovirus Infections with Esophageal Carcinoma

Background: Given the fact that viral infections play an important role, either directly or indirectly, in around 20 percent of human cancers, this study aimed at investigating the potential association of Epstein–Barr virus (EBV) and cytomegalovirus (CMV) infections in esophageal cancer that is the sixth most common cause of cancer-related deaths. Methods: In this case-control study, a total of 200 paraffin-embedded biopsies of cancerous and benign esophageal tissues were gathered from the biopsy bank of Imam Reza Hospital, Tabriz, Iran in 2017. All samples were first deparaffinized, and then subjected to commercial DNA extraction. The quality of extracted DNA was evaluated by amplification of the beta globulin gene. Identification of EBV and CMV DNA was performed using primers designed for the EBER region of EBV and the immediate early (IE) region of the CMV genome, respectively. Results: The mean age of the subjects in the test and control groups was 52.2 (17.1) and 59.9 (18.9), respectively. The distribution of gender (male/female) in patient and control groups was 54/46 and 53/47, respectively. Our results showed that the frequency of EBV (P < 0.001) and CMV (P < 0.001) in cancerous samples was statistically higher than control group. Moreover, in the cancerous group the rate of EBV was significantly higher in the esophageal adenocarcinomas (EAC) sample (12 out of 70) than esophageal squamous cell carcinomas (ESCC) (0 out of 30) (P = 0.016) but, in the ESCC group, 17 out of 30 subjects were positive for CMV which was significantly higher in comparison with EAC patients (1 out of 70) (P < 0.001). Conclusions: Findings indicated that EBV and CMV might be contributed to the pathogenesis of EAC and ESCC types of esophageal carcinoma, respectively, although further studies are warranted.

Perturbation of miR-146b and relevant inflammatory elements in esophageal carcinoma patients supports an immune downregulatory mechanism

BACKGROUND

Esophageal Cancer is known as one of the deadliest cancers worldwide with the squamous cell carcinoma (ESCC) being the predominant subtype. There is a growing body of evidence linking the dysregulated microRNA (miRNA) pathway of immune cells to the progression of several tumors. In a previous study, we investigated molecular alterations pertaining to miR-146a and some components of NF-kB signaling pathway and proposed a possible immune downregulatory mechanism in peripheral blood mononuclear cells (PBMCs) of ESCC patients. Here, we further scrutinized other components of this pathway by evaluating PBMC levels of miR-146b, TLR4, IL10, and TNFA.

METHODS

Gene expressions were quantified using RT-qPCR assays. To prevent the vulnerability of results to the expression instability of reference genes, nine additional transcripts were quantified, and stable reference genes for normalizing qPCR data were identified using the NormFinder and the geNorm algorithms. The efficiency-corrected normalized relative quantity values were used to compare gene expressions among study groups.

RESULTS

The PBMC expression of miR-146b and TNFA was downregulated in ESCC patients as compared to healthy subjects. While the level of TLR4 was not different among the study groups, the PBMC level of IL10 was upregulated in ESCC patients. Logistic regression analyses coupled with the ROC curve and cross-validation analysis suggested that PBMC expression may serve as potential candidate biomarker for discriminating ESCC patients from healthy subjects.

CONCLUSION

The present findings, in line with our previous report, propose a particular gene expression pattern in PBMCs of ESCC patients, providing evidence in support of an immune downregulatory mechanism.

National and Subnational Cancer Incidence for 22 Cancer Groups, 2000 to 2016: A Study Based on Cancer Registration Data of Iran

BACKGROUND

Cancer is an increasing public health concern, and detailed knowledge of the cancer incidence is required for developing effective cancer control plans. The objective of this study is to present the cancer incidence of 22 cancer groups in Iran and all 31 provinces of the country from 2000 to 2016, for both sexes across different age groups.

METHOD

To study the national and provincial cancer incidence in Iran, we extracted data from the Cancer Project, which collects the Iranian cancer registry data and visualizes it in the VIZIT data visualization system. The methodology and statistical analysis that is used in this study follow the cancer project study protocol. Joinpoint analysis was performed to calculate the average annual percent change of the crude rates and age-standardized rates from 2000 to 2016.

RESULTS

Cancer incidence was 126,982 patients in 2016, and the crude rate (CR) of cancer in both sexes and all ages was 155 per 100,000 people. Cancer incidence approximately doubled between 2000 and 2016; however, the age-standardized rate (ASR) had a less drastic increase. The most incident cancers in 2016 were breast, skin, and colorectal cancers; however, the ranking of cancer groups by incidence was different in different age and sex groups and provinces. Some cancers exhibited a unique distribution pattern in the country with high-incidence local areas. Discussion. The study showed that cancer incidence, crude rate, and age-standardized rate (ASR) in Iran had increased in 2000-2016 with vast heterogeneity by cancer type, province, and sex. Moreover, it was shown that the crude rate of cancer in Iran was much less than the global cancer crude rate. Providing such data helps to allocate resources and develop effective national cancer control plans appropriately.

Oral Health and Risk of Upper Gastrointestinal Cancers in a Large Prospective Study from a High-risk Region: Golestan Cohort Study

Tooth loss and periodontal disease have been associated with several cancers, and poor oral health may be an important risk factor for upper gastrointestinal (UGI, i.e., esophageal and gastric) cancers. We assessed the relationship between oral health and UGI cancers using a large prospective study of over 50,000 adults living in Golestan Province, Iran, a high-incidence area for these cancers. Hazard ratios (HRs) and 95% confidence intervals (CI) were estimated for the association between three different measures of oral health [frequency of tooth brushing; number of missing teeth; and the sum of decayed, missing, and filled teeth (DMFT)] and UGI cancers. During a median follow-up duration of 13 years, there were 794 incident UGI cancers (396 esophageal and 398 gastric cancers). Daily tooth brushing was associated with a decreased risk of developing both esophageal (HR = 0.670; 95% CI: 0.486-0.924) and gastric (HR = 0.741; 95% CI: 0.544-1.01) cancers (combined UGI cancer HR = 0.697; 95% CI: 0.558-0.871) compared with never brushing. Tooth loss in excess of the loess smoothed, age- and sex-specific median number of teeth lost was significantly associated with esophageal (HR = 1.64; 95% CI: 1.08-2.47) and gastric cancers (HR = 1.58; 95% CI: 1.05-2.38). There were some adverse associations between DMFT and UGI cancers but most were not statistically significant. These results suggest increased risk of developing UGI cancers among individuals with poor oral health, and those who do not perform regular oral hygiene. PREVENTION RELEVANCE: Poor oral health is associated with the risk of upper gastrointestinal cancers, and oral hygiene practices may help prevent these cancers.

MAEL as a diagnostic marker for the early detection of esophageal squamous cell carcinoma

Background

Esophageal cancer is one of the most common malignancies among Iranians and is categorized as adenocarcinoma and squamous cell carcinoma. Various environmental and genetic factors are involved in this malignancy. Despite the recent advances in therapeutic modalities there is still a noticeable mortality rate among such patients which can be related to the late diagnosis. Regarding high ratio of esophageal squamous cell carcinoma (ESCC) in Iran, therefore it is required to assess molecular biology of ESCC to introduce novel diagnostic markers. In present study we assessed the role of Maelstrom (MAEL) cancer testis gene in biology of ESCC among Iranian patients.

Methods

Forty-five freshly normal and tumor tissues were enrolled to evaluate the levels of MAEL mRNA expression using Real time polymerase chain reaction.

Results

MAEL under and over expressions were observed in 12 (26.7%) and 9 (20%) of patients, respectively. MAEL fold changes were ranged between -4.33 to -1.87 (mean SD: -2.90± 0.24) and 1.92 to 7.72 (mean SD: 3.97± 0.69) in under and over expressed cases, respectively. There was a significant association between stage and MAEL expression in which majority of MAEL over expressed tumors (8/9, 88.9%) were in stage I/II (p<0.001). There was also a significant correlation between MAEL expression and depth of invasion in which tumor with T1/2 had higher levels of MAEL expression compared with T3/4 tumors (p=0.017). Moreover, there were significant correlations between MAEL expression, tumor size (p=0.028), and grade (p=0.003) among male patients.

Conclusions

Our data showed that the MAEL was mainly involved in primary stages of tumor progression and it has a declining expression levels toward the advanced stages and higher depth of tumor invasions. Therefore, MAEL can be efficiently introduced as an early detection marker among Iranian ESCC patients.

Cadmium inhibits apoptosis of human esophageal epithelial cells by upregulating CDK6

Cadmium (Cd) exposure in environment is associated with development of esophageal cancer. However, the mechanisms of Cd-induced carcinogenesis are still not been fully cleared, and the present study aimed to explore the possible etiological mechanism of Cd-induced esophageal cancer. Human esophageal epithelial cell lines (HET-1A and KYSE450) were treated with CdCl₂ at 0.05 mg/l for 12, 24 h, and the then the apoptosis were detected using flow cytometry with annexin-V-FITC/PI staining. Results showed that apoptosis of treatment groups was significantly inhibited, and decreased reactive oxygen species (ROS) production played a key role in the inhibitory effects by upregulating Bcl-2 and downregulating Caspase-3/9. The relief of oxidative stress during Cd exposure was actively promoted by the increased nicotinamide adenine dinucleotide phosphoric acid and glutathione levels. To investigate the causes of enhanced intracellular antioxidant capacity, the activity of pyruvate kinase (PK), a key enzyme of glycolysis, was detected. Our results showed that PK activity was inhibited, suggesting that glycolysis process was blocked which promoted more intermediate metabolites of glycolysis to be used for reduced nicotinamide adenine dinucleotide phosphoric acid (NADPH) or other antioxidants synthesis. PK activity was closely correlated with phosphorylation of pyruvate kinase M2 (PKM2), and a highly negative correlation (correlation coefficients: -0.835, p < 0.05) between them was found. Western blotting showed the overphosphorylation of PKM2 in Cd-exposed cells, resulting from increased expression of cyclin-dependent kinases 6 (CDK6). These results suggested a possible mechanism of carcinogenic: Cd-induced upregulation of CDK6 in esophageal cell lines caused PKM2 overphosphorylation inhibiting PK activity, thereby shunting glucose-derived carbon into the pentose phosphate pathway and promoting the production of NADPH and reduced glutathione (GSH) to neutralize ROS, which finally results in the inhibited apoptosis.

Esophageal cancer in Aleppo, Syria 2010-2020: a rare cancer in a war zone

The management of diseases such as cancer in developing countries are often suboptimal given a lack of resources and access to specialists and therapeutics. In March 2020, Syria descended into its ninth year of the war with a rising death toll and millions of Syrian refugees. Aside from the inherent dangers of war, cancer care during war is especially difficult with partially or non-functional infrastructure due to destruction, inconsistent electrical power, inaccessibility, or the inherent dangers of living in a war zone. Furthermore, limitations to therapeutics are exacerbated when supply chains responsible for bringing in essential medications such as chemotherapeutics are disrupted by international economic sanctions. Aleppo, Syria is the site of some of the fiercest fighting which ended in December 2016. Since then, Aleppo has made a slow recovery to rebuild its infrastructure while the war continues elsewhere in the country. In this article, we aim to highlight the challenges in the management of cancer, particularly esophageal cancer, during a time of war in Aleppo, Syria. We aim to discuss current challenges and limitations to care in a war zone. We will also touch upon areas of need for continued improvement in the care of cancer patient's in Aleppo, Syria.

GSTs polymorphisms are associated with epigenetic silencing of CDKN2A gene in esophageal squamous cell carcinoma

Esophageal cancer is the eighth most common cancer and the sixth most frequent cause of cancer mortality worldwide. Exposure to polycyclic aromatic hydrocarbons formed by incomplete combustion of organic matter is an important risk factor. Genetic polymorphisms in genes encoding PAH-metabolizing enzymes like glutathione S-transferases (GSTM1, GSTP1, GSTT1) which conjugate glutathione to PAHs for reduction of oxidative stress may affect an individual's response to PAH exposure. Genomic DNA from 50 esophageal squamous cell carcinoma patients extracted from peripheral blood. PCR-RFLP technique was employed to determine GSTM1, GSTT1, and GSTP1 polymorphisms. Aberrant promoter methylation of CDKN2A was applied by methylation-specific PCR technique. Concentration of urinary 1-hydroxypyrene was determined using a HPLC system. About 38.7% showed the null GSTM1 genotype (54% cases and 13% controls), 23.7% showed GSTT1 null genotype (30% cases and 13% controls), and 62.5% were GSTP1 A/A genotype (66% cases and 56% controls). Polymorphic variants of GSTM1 and GSTT1 were significantly associated with aberrant methylation of CDKN2A gene. The null state of GSTT1 was significantly associated with high concentrations of 1-OHP in urea (p < 0.01). There was significant association between methylated states of CDKN2A and high concentrations of 1-OHP in urine (p < 0.01). We identified significant association between polymorphism of GSTs genes and epigenetic silencing of tumor suppressor gene CDKN2A in esophageal squamous cell carcinoma.

Strontium and antimony serum levels in healthy individuals living in high- and low-risk areas of esophageal cancer

Background

It has been shown there is an upward trend for strontium (Sr) and antimony (Sb) levels from low‐risk (LR) to high‐risk (HR) areas of etiology of esophageal cancer in water, soil, and grains grown in Golestan province. In the present study, the serum levels of Sr and Sb were determined in healthy individuals living in these areas.

Methods

This cross‐sectional study was performed on fasting blood serum of adult healthy individuals collected by cluster sampling. Subjects were divided into two groups, those living in either HR or LR areas. Strontium and antimony serum levels were measured using a graphite furnace atomic absorption spectroscopy.

Results

A total of 200 volunteers were enrolled from which 96 persons (48%) and 104 persons (52%) were from either HR or LR areas, respectively. The sex distribution was 40.9% male and 59.1% female, and the average age of enrolled people was 50.9 years. The average strontium levels were 30.44 ± 4.05 and 30.29 ± 3.74 μg/L in LR and HR, respectively. It also has been shown the average antimony levels were 15.21 ± 3.40, 14.81 ± 3.17, 15.13 ± 3.62, and 15.07 ± 3.62 μg/L in LR, HR, urban, and rural populations, respectively.

Conclusion

The serum levels of strontium and antimony were not significantly different in healthy adults living in high‐ and low‐risk areas of esophageal cancer. However, the average antimony serum levels in Golestan Province were above the reference interval in different countries.

Upregulation of Fucosyltransferase 3, 8 and protein O-Fucosyltransferase 1, 2 genes in esophageal cancer stem-like cells (CSLCs)

Recently, studies have shown that Fucosylation plays an important role in the invasion and metastatic process of CSLCs. Understanding the expression pattern of fucosyltransferase (FUT) genes may help to suggest better-targeted therapy strategies for esophageal squamous cell carcinoma (ESCC). The study aimed to address the expression pattern of FUT gene variants in esophageal CSLCs and parental adherent cells. Sphere formation method was used to enrich CSLCs. Expression of FUT genes was examined in tumor sphere and parental adherent cells using the RT-PCR method and then relative expression of detected variants was performed by the Real-Time PCR method in both groups. The detected FUTs, also, were assessed in fresh ESCC tumors and the matched healthy controls. Analysis of The cell surface carbohydrate Lewis x (LeX, CD15) was performed by flow cytometry. Molecular analysis showed that the expression of FUT 3, 8 and POFUT1, 2 genes in tumorsphere were significantly higher than parental adherent cells. Analysis of fresh ESCC tumor tissues and the matched healthy controls showed that FUT8 and POFUT1, 2 genes in contrast to FUT 3 have higher expression in tumor tissues than controls. Flow cytometric analyses revealed that tumorsphere and their parent cells do not differ significantly in Lewis x surface marker. The present study showed that FUT 3, 8 and POFUT1, 2 genes upregulated in esophageal CSLCs in comparison to adherent cells. Understanding the expression pattern of FUT gene variants may help to suggest better-targeted therapy strategies for ESCC.

Evaluation of Haptoglobin Genotype and Some Risk Factors of Cancer in Patients with Early Stage Esophageal Cancer

INTRODUCTION

Esophageal cancer is one of the most lethal gastrointestinal cancers that has a complex and diverse etiology, with several genetic and nutritional factors involved in its etiology. The purpose of this study was to investigate the type of haptoglobin genotype and its relationship with some nutritional and biochemical risk factors affecting the prevalence of esophageal cancer in patients with early stage esophageal cancer.

MATERIALS AND METHODS

In this study, 44 patients (20 males and 24 females) with early stage esophageal cancer and 44 healthy subjects, classified as control group, (19 males and 25 females) were selected. Haptoglobin (HP) genotype was determined employing PCR technique. Nutritional data were analyzed using standard food frequency questionnaire (FFQ) method. Serum levels of malondialdehyde (MDA), nitrate and nitrite were measured employing the colorimetric method. Serum levels of p53 protein were measured using the enzyme-linked immunosorbent assay (ELISA) technique.

RESULTS

The results of our study showed for the first time that HP1-1 genotype was the most prevalent genotype in esophageal cancer patients in Golestan province, Iran. HP2-2 genotype was the most frequent in the control group. Serum levels of MDA were significantly higher in the patients' group compared to the control group (P˂0.001). Weight and body mass index (BMI) were significantly lower in the patients' group than the control group (P<0.01). Food frequency analysis revealed that the consumption of fruits and vegetables in the patients' group was lower than that of the control group (P<0.05).

CONCLUSION

The results of our study showed for the first time that HP1-1 genotype is the dominant genotype in patients with esophageal cancer in Golestan province. As well, modification of nutritional pattern and consumption of high level of antioxidant compounds can be effective in reducing the prevalence of esophageal cancer in this region.

A 12-year trend analysis of the incidence of gastrointestinal cancers in East Azerbaijan: last updated results of an ongoing population-based cancer registry

BACKGROUND

The most recent results of Global Cancer Statistics indicated that gastrointestinal cancers, including gastric, colorectal, esophageal, and liver cancers, are among the most commonly diagnosed cancers worldwide. Previous reports from cancer registries in East Azerbaijan have shown that there is a high incidence of gastrointestinal cancer in this region, so we performed a trend analysis to determine the pattern of change over the last decade.

METHODS

In total, 12 years of cancer registry data were collected from different sources in East Azerbaijan, and a data quality check was performed to ensure clean data. Using the 2000 World Health Organization standard population, we then generated age-standardized incidence rates (ASRs) for different cancers, and for each year from 1383 to 1394 of the Persian calendar (i.e., 19 March 2004 to 20 March 2015). Annual percent changes (APCs) and Average annual percent changes (AAPCs) in the ASRs for esophageal, gastric, small intestine, colorectal, anal, liver, gallbladder, and pancreatic cancers were calculated using Joinpoint Software (Version 4.5.0.1, June 2017).

RESULTS

An increase in most types of cancer was observed during the study period. The ASR for colorectal cancer increased from 2.9 to 13.6 per 100,000 women (APC, 9.7%) and from 2.2 to 17.8 per 100,000 men (APC, 10.2%). The ASR for gastric cancer showed a slight increasing trend from 10.5 to 13.5 per 100,000 women (APC, 1.3%) and from 3.1 to 29.9 per 100,000 men (APC, 3.2%). However, trend analysis showed a decreasing pattern for the ASR of esophageal cancer in both genders (APC,- 3%), with APCs of - 1.1% in females and - 0.4% in males.

CONCLUSIONS

The latest results of the East Azerbaijan Population-Based Cancer Registry indicate that gastrointestinal cancers remain common, with significant increasing trends in their ASRs. Improved screening and early detection are needed in this region.

Effects of exposure to polycyclic aromatic hydrocarbons combined with high-risk human papillomavirus infection on cervical intraepithelial neoplasia: A population study in Shanxi Province, China

High-risk human papillomavirus (HR-HPV) infection is a major etiological agent in the progression of cervical intraepithelial neoplasia (CIN) and cervical cancer. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic pollutants that exist widely in the environment. We hypothesized that PAHs exposure was related to the progression of cervical cancer, and could increase the effect of HR-HPV on CIN. We investigated the effects of PAHs exposure combined with HR-HPV infection on CIN in community population in Shanxi Province, China. A total of 2,285 women were enrolled into the study. HR-HPV genotypes were detected by flow-through hybridization technology. 1-hydroxypyrene (1-OHP) was detected by high-performance liquid chromatography. The top three HR-HPV genotypes were 16, 58 and 52 in turn. With unconditional logistic regression analysis, we found that HR-HPV infection (adjusted odds ratio [aOR] = 4.08, 95% confidence interval [CI]: 3.00-5.54), HPV16 infection (aOR = 4.71, 95% CI: 3.39-6.53), HPV58 infection (aOR = 2.29, 95% CI: 1.41-3.73) and PAHs high exposure (aOR = 2.57, 95% CI: 1.82-3.62) increased the risk of CIN2/3, showing an increasing trend (p < 0.001) with the severity of cervical lesions. Compared to Q1 (<0.06 μmol/molCr) levels of 1-OHP, women with Q4 (>0.11 μmol/molCr) had a higher risk for CIN2/3 (aOR = 7.68, 95% CI: 4.83-12.22). Additionally, we observed that there was a synergic effect between high exposure to PAHs and HR-HPV infection in CIN2/3. Furthermore, the results from the generalized multifactor dimensionality reduction model showed that there were joint interactions of PAHs, HPV16, HPV58 and HPV52 on the risk of CIN2/3. Our study revealed that high exposure to PAHs could increase the risk for CIN, and it posed stronger risk when combined with HR-HPV infection.

Validation study of susceptibility loci for esophageal squamous cell carcinoma identified by GWAS in a Han Chinese subgroup from Eastern China

Esophageal squamous cell carcinoma (ESCC) occurs at a relatively high frequency in China and is one of the most prevalent cancers in the world. Genome-wide association studies (GWAS) have identified 24 single-nucleotide polymorphisms (SNPs) that could be associated with ESCC in Chinese patients. This retrospective study aimed to validate the association between these 24 SNPs and ESCC in a Han Chinese subgroup from East China. A total of 2280 and 1900 patients with ESCC (case group) and non-esophageal cancer (control group) were included from a single center. Genotyping of the 24 polymorphisms was performed using the Sequenom MassARRAY system. Unconditional logistic regression analyses were conducted for every polymorphism. It was found that rs12188136 (P=0.027, OR=1.158, 95% CI=1.016-1.319 for AG/AA) was associated with ESCC. Binary logistic regression analyses revealed a significant negative association of rs875339 in RORA (P=0.014, OR=0.762, 95% CI=0.613-0.947 for TT/CC). Under the dominant model, rs6854472 was slightly associated with ESCC risk (P=0.048, OR=1.192, 95% CI=1.002-1.418). Under the recessive model, a significant negative association was observed for rs875339 (P=0.010, OR=0.758, 95% CI=0.615-0.935). In a word, this large-scale replication study validated that rs12188136 and rs6854472 are associated with ESCC in a Han Chinese subgroup from Eastern China, and that rs875339 is negative associated with ESCC.

miR-671-5p Blocks The Progression Of Human Esophageal Squamous Cell Carcinoma By Suppressing FGFR2

Esophageal cancer is the eighth most common malignant tumor worldwide, of which esophageal squamous cell carcinoma (ESCC) is the dominant histological subtype. A drug shortage for ESCC therapy triggered us to explore the roles of fibroblast growth factor receptor 2 (FGFR2) and its upstream regulator miR-671-5p in ESCC progression. We compared the levels of FGFR2 and miR-671-5p between human ESCC tissues and their matched normal esophageal tissues and found an association between higher levels of FGFR2 and lower levels of miR-671-5p in ESCC tissues. High levels of FGFR2 resulted in the activation of the ERK and AKT pathways and a promotion of ESCC progression. High levels of miR-671-5p specifically reduced the expression of FGFR2 and suppressed ESCC progression in both in vitro and in vivo models. Therefore, suppressing FGFR2 and enhancing miR-671-5p expression may be the right approaches for ESCC therapy.

Prevalence and Association of Human Papillomavirus with Esophageal Squamous Cell Carcinoma in Iran: A Systematic Review and Meta-Analysis

BACKGROUND

Human papillomavirus (HPV) can infect the epithelium of the esophagus, but so far there is no reliable and comprehensive evidence about the prevalence and association of HPV with esophageal cancer in Iran, as high incidence region. This study aimed to evaluate the prevalence and association of HPV with esophageal squamous cell carcinoma (ESCC) in Iran.

METHODS

Relevant English and Persian articles published up to Aug 2017 and indexed in databases were reviewed. Frequency of HPV genotypes in ESCC cases and controls was surveyed according to regions of Iran. Data were meta-analyzed with random effects models using Comprehensive Meta-Analysis software.

RESULTS

Overall, 14 studies were eligible including 1444 samples (1062 ESCC cases and 382 controls). HPV was positive in 269 (25.32%) of 1062 ESCC cases and in 65 (17.01%) of 382 controls. Total prevalence of HPV in both groups was estimated 0.256 (95%CI, 0.208%-0.310%). The prevalence of HPV-16 and HPV-18 was estimated 0.121 (95%CI: 0.087-0.183) and 0.046 (95%CI; 0.023-0.088), respectively. The difference in HPV prevalence in different regions of Iran was statistically significant (Q=18.20, df =4, P=0.001). In 6 case-control studies, the pooled odds ratio was estimated 1.99 (95%CI; 0.916-4.315).

CONCLUSION

High-risk HPVs were observed in ESCC cases and controls from different regions of Iran. The odds ratio indicates that the HPV infection in ESCC cases was approximately 2 fold more than the controls. More case-control studies in other populations with larger sample size are necessary.

Causes of premature death and their associated risk factors in the Golestan Cohort Study, Iran

OBJECTIVES

To examine the causes of premature mortality (<70 years) and associated risk factors in the Golestan Cohort Study.

DESIGN

Prospective.

SETTING

The Golestan Cohort Study in northeastern Iran.

PARTICIPANTS

50 045 people aged 40 or more participated in this population-based study from baseline (2004-2008) to August 2017, with over 99% success follow-up rate.

MAIN OUTCOME MEASURES

The top causes of premature death, HR and their 95% CI and population attributable fraction (PAF) for risk factors.

RESULTS

After 444 168 person-years of follow-up (median of 10 years), 6347 deaths were reported, of which 4018 (63.3%) occurred prematurely. Ischaemic heart disease (IHD) accounted for 33.9% of premature death, followed by stroke (14.0%), road injuries (4.7%), stomach cancer (4.6%) and oesophageal cancer (4.6%). Significant risk/protective factors were: wealth score (HR for highest vs lowest quintile: 0.57, PAF for lowest four quintiles vs top quintile: 28%), physical activity (highest vs lowest tertile: 0.67, lowest two tertiles vs top tertile: 22%), hypertension (1.50, 19%), opium use (1.69, 14%), education (middle school or higher vs illiterate: 0.84, illiterate or primary vs middle school or higher: 13%), tobacco use (1.38, 11%), diabetes (2.39, 8%) and vegetable/fruit consumption (highest vs lowest tertile: 0.87, lowest two tertiles vs top tertile: 8%). Collectively, these factors accounted for 76% of PAF in men and 69% in women.

CONCLUSION

IHD and stroke are the leading causes of premature mortality in the Golestan Cohort Study. Enhancing socioeconomic status and physical activity, reducing opium and tobacco use, increasing vegetable/fruit consumption and controlling hypertension and diabetes are recommended to reduce premature deaths.

Chaperonin-containing T‑complex protein 1 subunit 8 promotes cell migration and invasion in human esophageal squamous cell carcinoma by regulating α-actin and β-tubulin expression

The chaperonin-containing T‑complex protein 1 (CCT) has eight subunits, CCT 1-8, which are dysregulated in several types of cancer. To determine how subunit 8 (CCT8) influences the development of esophageal squamous cell carcinoma (ESCC), immunohistochemistry and western blot analysis were performed on 128 ESCC samples in the present study to measure the expression of CCT8. The prognostic value of CCT8 was analyzed using univariate and multivariate survival analyses. CCT8 knockdown in ESCC cells was performed and subsequently, the migration and invasion of ESCC cells was assessed. The results of immunohistochemistry and western blot analysis of ESCC tissue indicated that the expression of CCT8 in tumor tissues from patients with lymph node metastasis (LNM) was high whereas its expression in tissues from those without LNM was low. In addition, the overall survival rate of patients with high CCT8 expression was poor. It was demonstrated that CCT8 influenced the migration and invasion of ESCC cells by regulating α-actin and β-tubulin. Following CCT8 knockdown, cells were treated with cisplatin; it was demonstrated that α-actin and β-tubulin were downregulated and that cell apoptosis was enhanced. These data confirm that α-actin and β-tubulin are regulated by CCT8, and that increased CCT8 expression is associated with poor patient prognosis and cisplatin resistance in ESCC.

CYP1A2*1F Gene Variant, Alkaline Salt Tea Intake and Risk of Esophageal Squamous Cell Carcinoma

Unlike many other cancers, the relationship of CYP1A2*1F (rs762551) polymorphism with esophageal squamous cell carcinoma (ESCC) risk has not been assessed so far. To evaluate its association with ESCC, we conducted a case control study in Kashmir, India, a high risk region. We recruited 404 histopathologically confirmed ESCC cases and 404 controls, individually matched for sex, age and residence to the respective cases. Information was obtained on dietary, lifestyle and environmental factors in face to face interviews using a structured questionnaire from each subject. Genotypes were analyzed by polymerase chain reaction, restriction fragment length polymorphism and sequencing randomly selected samples. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs). We found that mutant genotype (AA) of CYP1A2*1F polymorphism was associated with ESCC risk (OR = 3.11; 95% CI: 1.72-5.36). A very strong ESCC risk was observed in subjects who drank >1250 ml of salt tea daily and harbored mutant genotype of CYP1A2*1F (OR = 14.51; 95% CI: 5.33-39.47). The study indicates that CYP1A2*1F polymorphism is associated with ESCC risk and the risk is modified in salt drinkers. However, more replicative and mechanistic studies are needed to substantiate the findings.

Integration of human papillomavirus 16 in esophageal carcinoma samples

Background

Esophageal carcinoma (EC) is one of the major cancers in China. In 1982, Syrjanen first hypothesized the relationship between human papillomavirus (HPV) infection and the development of esophageal cancer. Since then, many reports in the field have supported this viewpoint. This study investigated the etiological relationship between HPV infection and the occurrence of esophageal carcinoma at Tangshan City of the Hebei province in China.

Methods

189 samples of esophageal carcinoma patients were collected. DNA and RNA were isolated from samples, HPV DNA was detected by polymerase chain reaction (PCR) using My09/11 for HPV L1, and HPV16 was determined using type-specific primer sets for HPV16 E6. The HPV16 integration site was verified by amplification of papillomavirus oncogene transcripts, and HPV16 oncogene transcript products were ligated to the pMD-18 T vector and sequenced to confirm the physical location of HPV16 integration.

Results

168 HPV-positive samples were detected in 189 samples, and among them 76 specimens were HPV16 positive. Approximately 600 bp of the HPV16 oncogene transcript were detected in nine esophageal cancer samples. Sequence analysis revealed that HPV16 E7 integrated into human chromosome 2 in three samples, into human chromosome 5 in one sample, into human chromosome 6 in one sample, into human chromosome 8 in two samples, and into human chromosome 17 in two samples. The results verified that the integrated HPV16 E7 in five samples harbored one mutation of viral DNA compared with the HPV16 sequence provided in GenBank (K02718).

Conclusions

The high prevalence of HPV16 suggests that HPV16 may play an etiological role in the development of esophageal cancer. The integration of HPV16 into host cell chromosomes suggests that persistent HPV infection is key for esophageal epithelial cell malignant transformation and carcinogenesis.