Missing and decayed teeth, oral hygiene and dental staining in relation to esophageal cancer risk: ESCCAPE case-control study in Kilimanjaro, Tanzania

Poor oral health and the risk of esophageal squamous cell carcinoma in Malawi

Esophageal squamous cell carcinoma (ESCC) is the second most common cancer in Malawi. Risk factors for this cancer in Malawi are poorly understood. Poor oral health has previously been linked to increased ESCC risk in other high-incidence regions, including parts of Eastern and Southern Africa. We assessed the relationship between oral health and ESCC risk in a sex, age and location frequency-matched case-control study based at two hospitals in Lilongwe, Malawi from 2017 to 2020. Trained interviewers used a structured questionnaire and direct observation to collect data on demographics; behaviors; oral hygiene habits; the sum of decayed, missing or filled teeth (DMFT score); oral mucosa status; lip depigmentation and dental fluorosis via a visual scale. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CI), adjusted for known and suspected ESCC risk factors. During the study period, 300 cases and 300 controls were enrolled. Subjects in the highest tertile of DMFT score (≥7) had an increased risk of ESCC with an adjusted OR of 1.96 (95% CI: 1.16-3.36) compared to those with a DMFT score of 0. Severe dental fluorosis was associated with a statistically nonsignificant increased risk of ESCC (adjusted OR = 2.24, 95% CI: 0.97-5.49) compared to individuals with no fluorosis. Associations with oral mucosa status, lip depigmentation and toothbrushing method and frequency were mostly null or uncertain. Poor oral health, indicated by a higher DMFT score, was associated with increased ESCC risk in Malawi. Dental fluorosis is another possible risk factor in this population, but further evaluation is necessary to clarify any effects of fluorosis on ESCC risk.

Landscape of esophageal cancer in Northern Kenya: experience from Garissa Regional Cancer Center

Introduction

Esophageal cancer (EC) is the ninth most common cancer and the sixth leading cause of cancer deaths worldwide. More than 80% of cases and deaths from EC occur within developing countries. In Kenya, cancer is the second leading cause of non-communicable disease deaths, and the trend of cancer deaths is projected to increase as per the 2020 GLOBOCAN report showing 42,116 new cases annually with a mortality of 27,092 cases. EC is the leading cancer in men and the third most common in women in Kenya. The Garissa Regional Cancer Center (GRCC) is one of the three regional cancer centres in Kenya. Despite the rising EC incidence in the region, there is limited data about the clinicopathological features and treatment outcomes of EC, therefore, this is the first study to look at the landscape of EC in the northern Kenya region.

Methods

This was a retrospective study involving patients' file review of confirmed EC cases diagnosed or treated at the GRCC from 2019 to 2023. Data collected from each patient's chart included age, sex, risk factors, family history of EC, histological type, stage at diagnosis, treatment type and survival outcomes. For patients who were no longer in contact with the staff through clinic visits, the patients or their next of kin were contacted through phone calls for patients' survival status. Data were collected and stored using the STATA software.

Results

Over the study period, 124 esophageal cases were identified, 64 (51.4%) were males and 60 (48.4%) were females with a mean age of 57.56 years. In terms of risk factors, hot beverage consumption was the highest (47 cases, 37.9%), followed by history of peptic ulcer disease (27 cases, 21.8%), smoking (8.9%) and gastresophageal reflux disease (2 cases, 1.6%). Stage of diagnosis at presentation was stage 1 (1 case, 0.8%), stage 2 (22 cases, 17.8%), stage 3 (25 cases, 20.2%), stage 4 (50 cases, 40.3%), not staged (26 cases, 21%). The majority had squamous cell carcinoma (SCC) (105 cases, 84.7%), followed by adenocarcinoma (5 cases, 4%), anaplastic (5 cases, 4%), SCC+ adenocarcinoma (1 case, 0.8%), unknown histology (8 cases, 3.2%). Nearly all patients had triple assessment (Endoscopy, histology and staging scans) accounting for 92 cases (74.2%), 24 cases (20%) had endoscopy+ histology only, and 8 cases (3.2%) had only imaging scans. In terms of family history of EC, 20 cases (16.1%) had a family history of EC.Most of the patients were of ethnic Kenyan-Somali background (108 cases, Kenyan Somali, 87.1%) and majority were from Garissa County 96 cases (77.4%), 12 cases (9.7%) Wajir County, 12 cases (9.7%) from Tana River County and 4 cases (3.2%) from other counties. Many patients lacked health insurance (27 cases, 25.8%), while the majority paid out of pocket (92 cases,74.1%). Only 21% (26 cases) received chemotherapy alone, 5 cases (4%) got radiotherapy alone, 12.9% (16 cases) got chemoradiotherapy and a significant number of patients (77 cases, 62.1%) did not receive hospital-based cancer treatment.

Conclusion

This study is the first esophageal study at the GRCC and in northern Kenya in general. Our study confirmed the clinicopathological features of one of the most common cancers in Kenya and more so among Kenyan-Somalis.The study also validates the predominance of histological subtypes of esophageal SCC with the late presentation, short survival and significant loss of follow-up. We recommend future EC studies employing a large prospective design with a large sample size to determine the impact of the new GRCC on the outcomes of EC patients and the local community.

Drinking patterns, alcoholic beverage types, and esophageal cancer risk in Africa: a comprehensive systematic review and meta-analysis

Africa is the continent most affected by esophageal cancer in the world. Alcoholic beverages are controversially blamed, as esophageal cancer is a rare disease in several other countries ranked in the top 10 for consumption of alcoholic beverages. This study aims to conduct a comprehensive systematic review of published literature, statistically summarizing the strength of the association between drinking patterns and types, and the risk of esophageal cancer in Africa. A computerized search of reputable databases such as Medline/PubMed, EMBASE, Web of Science, and African Journals Online was performed to identify relevant studies published up to September 2023. The quality of the studies was evaluated using the Newcastle-Ottawa scale for case-control studies and the Agency for Healthcare Research and Quality tool for cross-sectional studies. A funnel plot and Egger test were utilized to assess potential publication bias. Meta-analyses were conducted using random-effects models with RevMan 5.3 and Stata software to estimate summary effects. The systematic review identified a total of 758,203 studies, primarily from Eastern and Southern Africa. The pooled samples across all studies comprised 29,026 individuals, including 11,237 individuals with cancer and 17,789 individuals without cancer. Meta-analysis revealed a significant association between alcohol consumption and the risk of esophageal cancer (odds ratio [OR] = 1.81; 95% confidence interval [CI], 1.50-2.19). Further analysis based on the frequency of alcoholic beverage consumption indicated a stronger association with daily (OR = 2.38; 95% CI, 1.81-3.13) and weekly (OR = 1.94; 95% CI, 1.32-2.84) drinkers in contrast to occasional drinkers (OR = 1.02; 95% CI, 0.81-1.29). Additionally, consumption of traditional alcoholic beverages was significantly associated with the risk of esophageal cancer in African populations (OR = 2.00; 95% CI, 1.42-2.82). However, no relationship has been established between the exclusive consumption of non-traditional drinks and the risk of esophageal cancer. In conclusion, the results of this study confirm the hypothesis that daily and weekly drinking patterns, significantly increase the risk of esophageal cancer in Africa, while occasional consumption does not show a significant association. Additionally, the consumption of traditional alcoholic beverages is notably linked to the risk of esophageal cancer in African populations.

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.

Why Am I Ill? Beliefs in Supernatural and Natural Causes of Ill Health at the Time of Diagnostic Workup of Patients With Esophageal Cancer in Tanzania

PURPOSE

An understanding of the cultural and context-specific perceptions of the causes of cancer is an important prerequisite for designing effective primary health prevention and early detection strategies. We aimed to use the Murdock Ill Health Theoretical Model to conceptualize views on illness causation among dysphagia-suffering patients undergoing diagnostic workup for esophageal cancer (EC) in Tanzania.

METHODS

At the end of a structured interview on lifestyle habits, patients with suspected EC were asked about beliefs on the reasons behind their illness through (1) a set of questions with fixed binary answers, whose determinants were analyzed using logistic regression, and (2) a single question with free-text answers. Responses were coded using a hierarchy of natural and supernatural (godly and social constructs) causes.

RESULTS

Among 322 patients interviewed between November 2015 and December 2019, we found complex and varied views about the origins of their illness. Overall, 49% of patients attributed illness to natural causes and 39% to supernatural causes. Natural causes ranged from infection, use of alcohol and tobacco, other ailments, and the environment. The supernatural causes included attributing illness to God, curses, and spells from personal acquaintances. Belief in supernatural causes was more common in the less educated and those who sought help first via a traditional healer.

CONCLUSION

The results underscore the need for increased community awareness of biomedical causes of ill health and patient-based participatory research to inform prevention programs. The results also highlight the importance of building health systems that support a series of health-seeking behaviors that acknowledge both biomedical and local traditional healing belief systems.

Health risks associated with the production and usage of charcoal: a systematic review

Charcoal production and utilisation are linked to various health issues and occupational hazards. However, to our knowledge, no systematic review has primarily focused on the health implications of charcoal production and its use while distinguishing charcoal from other solid fuels such as wood and coal.

OBJECTIVES

This systematic review presents a synthesis of the evidence on the health risks associated with producing and using charcoal across the world.

DESIGN

Systematic review using a systematic narrative synthesis approach.

DATA SOURCES

MEDLINE (through Ovid interface), CINAHL, Embase, Web of Science, PsycINFO, Cochrane Library and SCOPUS, from inception to 26 February 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Peer-reviewed journal articles reporting empirical findings on the associations between charcoal usage/production and health parameters.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers extracted data and assessed the quality of primary studies.

RESULTS

Our findings showed that charcoal production and usage are linked with specific adverse health outcomes, including respiratory diseases (n=21), cardiorespiratory and neurological diseases (n=1), cancer (n=3), DNA damage (n=3), carbon monoxide (CO) poisoning (n=2), physical injury (n=2), sick house syndrome (n=1), unintentional weight loss and body mass index (BMI) reduction (n=2), increase in blood pressure (n=1) and CO death (n=1). Among the included articles that reported respiratory diseases (n=21), there was one case of asthma and tuberculosis and two cases of chronic obstructive pulmonary disease.

CONCLUSIONS

This review links charcoal production/usage and some associated human health risks. These include respiratory diseases and other non-respiratory illnesses such as sick-building syndrome, cardiovascular diseases, DNA damage, CO poisoning and death, unintentional weight loss and BMI reduction, and physical injuries.

Current Status and Future Prospects for Esophageal Cancer

Esophageal cancer (EC) is the ninth most common cancer and the sixth leading cause of cancer deaths worldwide. Esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) are the two main histological subtypes with distinct epidemiological and clinical features. While the global incidence of ESCC is declining, the incidence of EAC is increasing in many countries. Decades of epidemiologic research have identified distinct environmental exposures for ESCC and EAC subtypes. Recent advances in understanding the genomic aspects of EC have advanced our understanding of EC causes and led to using specific genomic alterations in EC tumors as biomarkers for early diagnosis, treatment, and prognosis of this cancer. Nevertheless, the prognosis of EC is still poor, with a five-year survival rate of less than 20%. Currently, there are significant challenges for early detection and secondary prevention for both ESCC and EAC subtypes, but Cytosponge™ is shifting this position for EAC. Primary prevention remains the preferred strategy for reducing the global burden of EC. In this review, we will summarize recent advances, current status, and future prospects of the studies related to epidemiology, time trends, environmental risk factors, prevention, early diagnosis, and treatment for both EC subtypes.

A very-hot food and beverage thermal exposure index and esophageal cancer risk in Malawi and Tanzania: findings from the ESCCAPE case-control studies

BACKGROUND

Consumption of very-hot beverages/food is a probable carcinogen. In East Africa, we investigated esophageal squamous cell carcinoma (ESCC) risk in relation to four thermal exposure metrics separately and in a combined score.

METHODS

From the ESCCAPE case-control studies in Blantyre, Malawi (2017-20) and Kilimanjaro, Tanzania (2015-19), we used logistic regression models adjusted for country, age, sex, alcohol and tobacco, to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for self-reported thermal exposures whilst consuming tea, coffee and/or porridge.

RESULTS

The study included 849 cases and 906 controls. All metrics were positively associated with ESCC: temperature of drink/food (OR 1.92 (95% CI: 1.50, 2.46) for 'very hot' vs 'hot'), waiting time before drinking/eating (1.76 (1.37, 2.26) for <2 vs 2-5 minutes), consumption speed (2.23 (1.78, 2.79) for 'normal' vs 'slow') and mouth burning (1.90 (1.19, 3.01) for ≥6 burns per month vs none). Amongst consumers, the composite score ranged from 1 to 12, and ESCC risk increased with higher scores, reaching an OR of 4.6 (2.1, 10.0) for scores of ≥9 vs 3.

CONCLUSIONS

Thermal exposure metrics were strongly associated with ESCC risk. Avoidance of very-hot food/beverage consumption may contribute to the prevention of ESCC in East Africa.

Association between the frequency of tooth brushing and esophageal carcinoma risk: an update systematic review and meta-analysis

Background

Lower frequency of tooth brushing was thought to be associated with esophageal carcinoma (EC). However, some researchers suggested that this association did not exist or had not yet reached statistical significance. The purpose of this study was to calculate a more precise estimation of the relationship between the frequency of tooth brushing and the risk of EC by combining the results between different studies using the meta-analysis.

Methods

We searched the PubMed, Embase, Web of Science, and Scopus electronic databases up to July 2021. According to PECO approach (Population, Exposure, Comparator and Outcomes), we assessed the association between tooth brushing frequency and EC risk which reported the adjusted risk ratios (adjRR), hazard ratios (adjHR), or odds ratios (adjOR) with 95% confidence interval (CI). The random effects model was used to quantitatively evaluate the combined results. Two researchers independently evaluated the risk bias of the included studies using the Newcastle-Ottawa Scale (NOS). The robustness of results was evaluated by subgroup analysis, sensitivity analysis, and publication bias.

Results

In total, we identified 13 articles with 14 case-control studies which included 16,773 participants and 5,673 patients. Pooled results showed the lowest frequency of brushing was significantly associated with an increased risk of EC in comparison to the highest (adjOR: 2.00, 95% CI: 1.61-2.48). There was moderate heterogeneity among included studies (P=0.001, I2=61.4%). The original studies included in this meta-analysis were all case-control studies. Study quality was all moderate or above based on NOS score ranges of 6 stars or more.

Conclusions

Available evidence suggests a low frequency of tooth brushing may be an important risk factor for EC. However, higher quality studies should continue to be conducted to investigate the optimal threshold of brushing frequency for the prevention of EC.

Risk Factors Associated With Early-Onset Esophageal Cancer in Tanzania

Eastern Africa is one of several regions affected by high incidence rates of esophageal squamous cell carcinoma (ESCC). A unique epidemiologic feature of ESCC in Eastern Africa is the high incidence in young people, with one-third of cases diagnosed at age < 45 years. This study aimed to investigate risk factors for early-onset ESCC in Tanzania through a secondary analysis of a matched case-control study.

Data from Tanzania show esophageal cancer risk factors in East Africa may differ across age groups.

Dietary patterns and severity of symptom with the risk of esophageal squamous cell carcinoma and its histological precursor lesions in China: a multicenter cross-sectional latent class analysis

Background

Dietary patterns and symptoms research among Chinese with esophageal squamous cell carcinoma (ESCC) and its precursor lesions is limited, especially as it relates to multiple food consumption and multiple co-occurring symptoms. The aim of our study was to identify the dietary patterns and severity of symptom classes with the risk of esophageal squamous cell carcinoma and its histological precursor lesions, and develop a risk prediction model for different stages of esophageal disease.

Methods

We analyzed data from a multicenter cross-sectional study carried out in ESCC high incidence areas between 2017 and 2018, which included 34,707 individuals aged 40–69 years. Dietary patterns and severity of symptom classes were derived by applying a latent class analysis (LCA). A multiple logistic regression model was used to derive the odds ratio (ORs) and corresponding 95% confidence intervals (CIs) for ESCC and the different stages of esophageal disease according to the dietary patterns and severity of symptom classes identified. We built the risk prediction model by using a nomogram.

Results

We identified five dietary patterns and three severity of symptom classes. The dietary patterns were classified as follows: “Healthy”, “Western”, “Lower consumers-combination”, “Medium consumers-combination” and “Higher consumers-combination” patterns based on the intake of foods such as red meat, vegetables and fruits. The severity of symptoms was categorized into “Asymptomatic”, “Mild symptoms” and “Overt symptoms” classes based on health-related symptoms reported by the participants. Compared to the “Healthy” pattern, the other four patterns were all associated with an increased risk of esophageal disease. Similarly, the other two symptom classes present different degrees of increased risk of esophageal disease compared to the “Asymptomatic”. The nomograms reflect the good predictive ability of the model.

Conclusion

Among individuals aged 40–69 years in high incidence regions of upper gastrointestinal cancer, the results supplied that subjects with diets rich in livestock and poultry meat and low in fruits and vegetables and subjects with typical symptoms were at increased ESCC risk. The findings highlight the importance of considering food and symptom combinations in cancer risk evaluation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09206-y.

Treatment outcomes of esophageal cancer in Eastern Africa: protocol of a multi-center, prospective, observational, open cohort study

Background

Esophageal squamous cell carcinoma (ESCC) is a major cause of cancer morbidity and mortality in Eastern Africa. The majority of patients with ESCC in Eastern Africa present with advanced disease at the time of diagnosis. Several palliative interventions for ESCC are currently in use within the region, including chemotherapy, radiation therapy with and without chemotherapy, and esophageal stenting with self-expandable metallic stents; however, the comparative effectiveness of these interventions in a low resource setting has yet to be examined.

Methods

This prospective, observational, multi-center, open cohort study aims to describe the therapeutic landscape of ESCC in Eastern Africa and investigate the outcomes of different treatment strategies within the region. The 4.5-year study will recruit at a total of six sites in Kenya, Malawi and Tanzania (Ocean Road Cancer Institute and Muhimbili National Hospital in Dar es Salaam, Tanzania; Kilimanjaro Christian Medical Center in Moshi, Tanzania; Tenwek Hospital in Bomet, Kenya; Moi Teaching and Referral Hospital in Eldoret, Kenya; and Kamuzu Central Hospital in Lilongwe, Malawi). Treatment outcomes that will be evaluated include overall survival, quality of life (QOL) and safety. All patients (≥18 years old) who present to participating sites with a histopathologically-confirmed or presumptive clinical diagnosis of ESCC based on endoscopy or barium swallow will be recruited to participate. Key clinical and treatment-related data including standardized QOL metrics will be collected at study enrollment, 1 month following treatment, 3 months following treatment, and thereafter at 3-month intervals until death. Vital status and QOL data will be collected through mobile phone outreach.

Discussion

This study will be the first study to prospectively compare ESCC treatment strategies in Eastern Africa, and the first to investigate QOL benefits associated with different treatments in sub-Saharan Africa. Findings from this study will help define optimal management strategies for ESCC in Eastern Africa and other resource-limited settings and will serve as a benchmark for future research.

Trial registration

This study was retrospectively registered with the ClinicalTrials.gov database on December 15, 2021, NCT05177393.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09124-5.

Human Microbiota in Esophageal Adenocarcinoma: Pathogenesis, Diagnosis, Prognosis and Therapeutic Implications

Esophageal adenocarcinoma (EAC) is one of the main subtypes of esophageal cancer. The incidence rate of EAC increased progressively while the 5-year relative survival rates were poor in the past two decades. The mechanism of EAC has been studied extensively in relation to genetic factors, but less so with respect to human microbiota. Currently, researches about the relationship between EAC and the human microbiota is a newly emerging field of study. Herein, we present the current state of knowledge linking human microbiota to esophageal adenocarcinoma and its precursor lesion—gastroesophageal reflux disease and Barrett’s esophagus. There are specific human bacterial alternations in the process of esophageal carcinogenesis. And bacterial dysbiosis plays an important role in the process of esophageal carcinogenesis via inflammation, microbial metabolism and genotoxicity. Based on the human microbiota alternation in the EAC cascade, it provides potential microbiome-based clinical application. This review is focused on novel targets in prevention, diagnosis, prognosis, and therapy for esophageal adenocarcinoma.

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.

Geophagia and risk of squamous cell esophageal cancer in the African esophageal cancer corridor: Findings from the ESCCAPE multicountry case-control studies

Geophagia, the intentional practice of consuming soil, occurs across the African esophageal cancer corridor, particularly during pregnancy. We investigated whether this practice is linked to endemic esophageal squamous cell carcinoma (ESCC) in this region. We conducted ESCC case-control studies in Tanzania, Malawi and Kenya. Cases were patients with incident histologically/clinically confirmed ESCC and controls were hospital patients/visitors without digestive diseases. Participants were asked if they had ever eaten soil (never/regularly/pregnancy-only). Odds ratios (OR) are adjusted for sex, age, tobacco, alcohol, country, religion and marital status. Overall, 934 cases (Malawi 535, Tanzania 304 and Kenya females 95) and 995 controls provided geophagia information. Among controls, ever-geophagia was common in women (Malawi 49%, Kenya 43% and Tanzania 29%) but not in men (10% Malawi, <1% Tanzania). In women, ESCC ORs were 1.25 (95% CI: 0.70, 2.22) for regular versus never geophagia and 0.88 (95% CI: 0.64, 1.22) for pregnancy-only versus never. Findings were stronger based on comparisons of cases with hospital visitor controls and were null using hospital patients as controls. In conclusion, geophagia is too rare to contribute to the male ESCC burden in Africa. In women, the practice is common but we did not find consistent evidence of a link to ESCC. The study cannot rule out selection bias masking modest effects. Physical effects of geophagia do not appear to have a large impact on overall ESCC risk. Research with improved constituent-based geophagia exposure assessment is needed.

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.

Indoor wood combustion, carcinogenic exposure and esophageal cancer in southwest Kenya

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a risk factor for esophageal squamous cell carcinoma (ESCC) in high-incidence areas of China, Iran and Brazil, but PAH assessments have not been conducted in East Africa, another ESCC hot spot.

OBJECTIVE

To evaluate demographic or lifestyle factors associated with the PAH biomarker concentrations in the study population, and whether PAH metabolite concentrations showed any associations with esophageal precancerous lesions.

METHODS

We recruited a community-based sample of 289 asymptomatic adults from a rural area of Kenya and performed Lugol's chromoendoscopy to detect esophageal squamous dysplasia (ESD); participants completed a questionnaire and provided a spot urine specimen. We analyzed urine for seven hydroxylated metabolites of naphthalene, fluorene, phenanthrene, and pyrene at the U.S. National Center for Environmental Health, and compared creatinine-corrected PAH metabolite concentrations with questionnaire data and the presence of ESD.

RESULTS

PAH metabolite concentrations among never tobacco users in these rural Kenya residents were 2.4-28.1 times higher than those reported from never tobacco users in Iran, Brazil and the USA. Female sex, cooking indoors, having no post-primary education, and age <50, but not tobacco use, were positively and significantly associated with PAH metabolite concentrations. Almost all participants used wood as cooking fuel. Nine participants had advanced ESD. Adjusted logistic regression showed a significant association between 2-hydroxynaphthalene (OR = 4.19, 95%CI: 1.01-17.47) and advanced ESD. All other PAH metabolites had positive but non-significant associations with advanced ESD.

CONCLUSIONS

Urinary PAH metabolite concentrations among never tobacco users are markedly higher in this group from Kenya than in other populations and are associated with indoor cooking with wood on open, unvented stoves. These metabolite concentrations were also associated with the presence of advanced esophageal dysplasia. Our findings underline the importance of assessing alternative cooking conditions to reduce PAH exposure in this population.

Missing and decayed teeth, oral hygiene and dental staining in relation to esophageal cancer risk: ESCCAPE case-control study in Kilimanjaro, Tanzania

In the African esophageal squamous cell carcinoma (ESCC) corridor, recent work from Kenya found increased ESCC risk associated with poor oral health, including an ill-understood association with dental fluorosis. We examined these associations in a Tanzanian study, which included examination of potential biases influencing the latter association. This age and sex frequency-matched case-control study included 310 ESCC cases and 313 hospital visitor/patient controls. Exposures included self-reported oral hygiene and nondental observer assessed decayed+missing+filled tooth count (DMFT index) and the Thylstrup-Fejerskov dental fluorosis index (TFI). Blind to this nondental observer TFI, a dentist independently assessed fluorosis on photographs of 75 participants. Odds ratios (ORs) are adjusted for demographic factors, alcohol and tobacco. ESCC risk was associated with using a chewed stick to brush teeth (OR 2.3 [95% CI: 1.3-4.1]), using charcoal to whiten teeth (OR 2.13 [95% CI: 1.3, 4.1]) and linearly with the DMFT index (OR 3.3 95% CI: [1.8, 6.0] for ≥10 vs 0). Nondental observer-assessed fluorosis was strongly associated with ESCC risk (OR 13.5 [95% CI: 5.7-31.9] for TFI 5+ v 0). However, the professional dentist's assessment indicated that only 43% (10/23) of participants assessed as TFI 5+ actually had fluorosis. In summary, using oral charcoal, brushing with a chewed stick and missing/decayed teeth may be risk factors for ESCC in Tanzania, for which dose-response and mechanistic research is needed. Links of ESCC with "dental fluorosis" suffered from severe exposure misclassification, rendering it impossible to disentangle any effects of fluorosis, extrinsic staining or reverse causality.