Qat use and esophageal cancer in Ethiopia: A pilot case-control study

Uncovering Risks Associated with Smoking Types and Intensities in Esophageal Cancer within High-Prevalence Regions in Africa: A Comprehensive Meta-analysis

Tobacco is usually cited among the well-known risk factors of esophageal cancer; nevertheless, the extent of the contribution of the type of smoking and its intensity to the disease has not been comprehensively elucidated in Africa. We searched MEDLINE/PubMed, Excerpta Medica Database, Web of Science, Scopus, Cochrane Library, and African Journals Online studies published before September 2023. The quality of the studies was assessed using the Newcastle-Ottawa scale, and the funnel plot was used for assessing potential publication bias. Meta-analyses were conducted to estimate summary effects using random-effects models. This study included 22,319 participants from 27 studies. The results strongly indicate a significant association between tobacco use and a higher risk of esophageal cancer. The risk of esophageal cancer is notably higher among pipe smokers [OR = 4.68; 95% confidence interval (CI), 3.38-6.48], followed by hand-rolled cigarette smokers (OR = 3.79; 95% CI, 2.68-5.35), in comparison with those who smoked commercially manufactured cigarettes (OR = 2.46; 95% CI, 1.69-3.60). Our findings also showed that the risk of esophageal cancer is highest in people smoking >183 packs per year (OR = 5.47; 95% CI, 3.93-7.62), followed by those smoking 93 to 183 packs per year (OR = 3.90; 95% CI, 3.13-4.86), in comparison with those smoking ≤92 packs per year (OR = 2.90; 95% CI, 2.19-3.84). Our findings strongly show that among the different types of tobacco use in Africa, pipe and hand-roller smokers face a higher risk of esophageal cancer.

Spatiotemporal Distribution, Time to Treatment Outcome Clustering and Determinants of Esophageal Cancer in Ethiopia, a Scoping Study

INTRODUCTION

Esophageal cancer was the eighth and sixth leading cause of morbidity of all cancers in the world, and the 15th and 12th in Ethiopia, respectively. There is a lack of comprehensive data regarding Ethiopia's esophageal cancer hotspot, treatment outcome clustering, and other factors.

OBJECTIVE

This scoping review was designed to understand the extent and type of existing evidence regarding spatiotemporal distribution, time to treatment outcome clustering, and determinants of esophageal cancer in Ethiopia up to March 28, 2023.

METHODS

Three-step search strategies were employed for the scoping review from March 15 to 28, 2023. Targeted databases included PubMed/Medline, PubMed Central (PMC), Google Scholar, Hinari, and Cochrane for published studies and different websites for unpublished studies for evidence synthesis. Data were extracted using the Joanna Briggs Institute (JBI) manual format.

RESULTS

Our final analysis comprised 17 (16 quantitative and 1 qualitative) studies. Three studies attempted to depict the country's temporal distribution, whereas 12 studies showed the spatial distribution of esophageal cancer by proportion. The regional state of Oromia recorded a high percentage of cases. Numerous risk factors linked to the tumor have been identified in 8 investigations. Similarly, 5 studies went into detail regarding the likelihood of survival and the factors that contribute to malignancy, while 2 studies covered the results of disease-related treatments.

CONCLUSIONS

The substantial body of data that underpins this finding supports the fact that esophageal cancer has several risk factors and that its prevalence varies greatly across the country and among regions. Surgery, radiotherapy, or chemotherapy helped the patient live longer. However, no research has investigated which treatment is best for boosting patient survival and survival clustering. Therefore, research with robust models for regional distribution, clustering of time to treatment outcomes, and drivers of esophageal cancer will be needed.

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.

Risk factors of oesophageal cancer at health facilities in Addis Ababa, Ethiopia: Unmatched case control study

Background

Oesophageal carcinoma is one of the most common cancers in Ethiopia. Its occurrences vary among regional states of the country. The identification of local risk factors of oesophageal cancer will make it simple to design a focused intervention. On local risk factors, there is, however, a shortage of empirical evidence. Therefore, the aim of study was to identify local risk factors.

Methods

An unmatched case control study design was employed. From February 2019 to August 2020, 338 histologically confirmed cases and 338 controls were recruited consecutively from six health facilities in Addis Ababa, Ethiopia’s capital city. To collect data from the cases and the controls, face to face interviews were conducted. Epi-info version 7 was used to enter and cleaned data, and SPSS version 23 was used to analyze it. The odds ratio was calculated based on hierarchal model multivariable logistic regression, and statistically significance was declared at p-value of <0.05.

Results

The mean (SD) age of the cases and the controls was 54.3 ± 12.5 years old and 40.2 ± 13.7 years old, respectively. The odds of oesophageal cancer was significantly higher among older ages (OR =11.0, 95% CI [6.60, 20.91]), rural residents (OR = 4.2, 95% CI [1.04, 16.80]), and those who had history of smoking (OR =1.3, 95% CI [1.12, 1.60]), khat chewing (OR = 4.0, 95% CI [2.50, 6.60]), raw meat consumers (OR = 2.6, 95% CI [1.75, 3.90]). Increasing monthly income (OR = 0.2, CI 95% [0.09, 0.49]) and a habit of eating fruits or vegetables (OR = 0.49, 95% CI [0.32, 0.76]) were associated with lower risks.

Conclusions

Tobacco smoking, khat chewing, age, residency, and red raw meat consumption were discovered to be positive predictors of oesophageal cancer, whereas fruit or vegetable consumption and higher monthly income were discovered to be inversely associated. It is advised to avoid the use of khat and tobacco, as well as to avail fruits and vegetables in dish.

Molecular tools, potential frontiers for enhancing salinity tolerance in rice: A critical review and future prospective

Improvement of salinity tolerance in rice can minimize the stress-induced yield losses. Rice (Oryza sativa) is one of Asia's most widely consumed crops, native to the subtropical regions, and is generally associated with sensitivity to salinity stress episodes. Salt-tolerant rice genotypes have been developed using conventional breeding methods; however, the success ratio is limited because of the complex nature of the trait and the high cost of development. The narrow genetic base of rice limited the success of conventional breeding methods. Hence, it is critical to launch the molecular tools for screening rice novel germplasm for salt-tolerant genes. In this regard, the latest molecular techniques like quantitative trait loci (QTL) mapping, genetic engineering (GE), transcription factors (TFs) analysis, and clustered regularly interspaced short palindromic repeats (CRISPR) are reliable for incorporating the salt tolerance in rice at the molecular level. Large-scale use of these potent genetic approaches leads to identifying and editing several genes/alleles, and QTL/genes are accountable for holding the genetic mechanism of salinity tolerance in rice. Continuous breeding practices resulted in a huge decline in rice genetic diversity, which is a great worry for global food security. However, molecular breeding tools are the only way to conserve genetic diversity by exploring wild germplasm for desired genes in salt tolerance breeding programs. In this review, we have compiled the logical evidences of successful applications of potent molecular tools for boosting salinity tolerance in rice, their limitations, and future prospects. This well-organized information would assist future researchers in understanding the genetic improvement of salinity tolerance in rice.

Dietary risk factors for esophageal cancer based on World Health Organization regions

OBJECTIVES

Esophageal cancer (EC) has become one of the most alarming cancers in the world. There are significant differences in incidence and risk factors associated with the two most common histological subtypes of EC, esophageal squamous cell carcinoma and esophageal adenocarcinoma, between regions. This systematic review was undertaken to analyze dietary risk factors specific to EC and its two subtypes based on World Health Organization regions.

METHODS

A systematic search of five databases (Global Health, Google Scholar, PubMed, Scopus, and Web of Science) for the past 5 y (2015-2020) was conducted from March 2020 to July 2020. Titles and abstracts were screened to determine the primary inclusion eligibility, followed by an examination of the full-text articles. Finally, 59 articles were reviewed to identify EC risk factors and compare these by region. Data were extracted using a table developed by the research team. Risk factors found in >50% of regions were highlighted.

RESULTS

The study identified some major dietary risk factors for EC that were previously reported, as well as some uncommon dietary risk factors, such as salty foods and beverages, unpiped drinking water, sugar-related factors (e.g., sweet intake), and foods with high glycemic index.

CONCLUSIONS

EC risk factors extend beyond those previously identified. Targeting all EC risk factors by region will assist the World Health Organization and other health agencies in providing a tailored, culturally appropriate response to effectively reduce the incidence and prevalence of EC within a region.

Genome-Wide DNA Methylation Profiling of Esophageal Squamous Cell Carcinoma from Global High-Incidence Regions Identifies Crucial Genes and Potential Cancer Markers

Epigenetic mechanisms such as aberrant DNA methylation (DNAme) are known to drive esophageal squamous cell carcinoma (ESCC), yet they remain poorly understood. Here, we studied tumor-specific DNAme in ESCC cases from nine high-incidence countries of Africa, Asia, and South America. Infinium MethylationEPIC array was performed on 108 tumors and 51 normal tissues adjacent to the tumors (NAT) in the discovery phase, and targeted pyrosequencing was performed on 132 tumors and 36 NAT in the replication phase. Top genes for replication were prioritized by weighting methylation results using RNA-sequencing data from The Cancer Genome Atlas and GTEx and validated by qPCR. Methylome analysis comparing tumor and NAT identified 6,796 differentially methylated positions (DMP) and 866 differential methylated regions (DMR), with a 30% methylation (Δβ) difference. The majority of identified DMPs and DMRs were hypermethylated in tumors, particularly in promoters and gene-body regions of genes involved in transcription activation. The top three prioritized genes for replication, PAX9, SIM2, and THSD4, had similar methylation differences in the discovery and replication sets. These genes were exclusively expressed in normal esophageal tissues in GTEx and downregulated in tumors. The specificity and sensitivity of these DNAme events in discriminating tumors from NAT were assessed. Our study identified novel, robust, and crucial tumor-specific DNAme events in ESCC tumors across several high-incidence populations of the world. Methylome changes identified in this study may serve as potential targets for biomarker discovery and warrant further functional characterization. SIGNIFICANCE: This largest genome-wide DNA methylation study on ESCC from high-incidence populations of the world identifies functionally relevant and robust DNAme events that could serve as potential tumor-specific markers. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/10/2612/F1.large.jpg.

Cancer in Africa: The Untold Story

Background

Despite rising incidence and mortality rates in Africa, cancer has been given low priority in the research field and in healthcare services. Indeed, 57% of all new cancer cases around the world occur in low income countries exacerbated by lack of awareness, lack of preventive strategies, and increased life expectancies. Despite recent efforts devoted to cancer epidemiology, statistics on cancer rates in Africa are often dispersed across different registries. In this study our goal included identifying the most promising prevention and treatment approaches available in Africa. To do this, we collated and analyzed the incidence and fatality rates for the 10 most common and fatal cancers in 56 African countries grouped into 5 different regions (North, West, East, Central and South) over 16-years (2002–2018). We examined temporal and regional trends by investigating the most important risk factors associated to each cancer type. Data were analyzed by cancer type, African region, gender, measures of socioeconomic status and the availability of medical devices.

Results

We observed that Northern and Southern Africa were most similar in their cancer incidences and fatality rates compared to other African regions. The most prevalent cancers are breast, bladder and liver cancers in Northern Africa; prostate, lung and colorectal cancers in Southern Africa; and esophageal and cervical cancer in East Africa. In Southern Africa, fatality rates from prostate cancer and cervical cancer have increased. In addition, these three cancers are less fatal in Northern and Southern Africa compared to other regions, which correlates with the Human Development Index and the availability of medical devices. With the exception of thyroid cancer, all other cancers have higher incidences in males than females.

Conclusion

Our results show that the African continent suffers from a shortage of medical equipment, research resources and epidemiological expertise. While recognizing that risk factors are interconnected, we focused on risk factors more or less specific to each cancer type. This helps identify specific preventive and therapeutic options in Africa. We see a need for implementing more accurate preventive strategies to tackle this disease as many cases are likely preventable. Opportunities exist for vaccination programs for cervical and liver cancer, genetic testing and use of new targeted therapies for breast and prostate cancer, and positive changes in lifestyle for lung, colorectal and bladder cancers. Such recommendations should be tailored for the different African regions depending on their disease profiles and specific needs.

Dietary and Environmental Determinants of Oesophageal Cancer in Arsi Zone, Oromia, Central Ethiopia: A Case-Control Study

PURPOSE

Oesophageal cancer is ranked 5th of all types of malignancies in Ethiopia and highly prevalent in the Arsi Zone. However, no study was conducted to elucidate the dietary and environmental determinants of oesophageal cancer in the Arsi Zone.

METHODS

A matched case-control study was conducted from June 1, 2019, to June 30, 2020. A total of 104 cases and 208 controls were interviewed. Data were collected using food frequency questionnaires (structured questionnaires). Binary and multiple logistic regression analyses were conducted to check the association between independent and dependent variables. Adjusted odds ratios and the corresponding 95% confidence intervals were estimated for the strength of association. Statistical significance was declared at a P-value of <0.05.

RESULTS

In multivariable logistic regression, drinking very hot coffee (AOR=5.1,[95% CI: (1.95, 13.71), drinking large volume of coffee (AOR=4.9, [95% CI: (2.03, 12.17), very hot porridge (AOR= 3.1,[95% CI: (1.38,7.03) and eating porridge fast (AOR=7.0, [95% CI: (2.48, 20.14), low intake of dairy products (AOR=6.0, [95% CI: (2.29, 15.95), cooking food in sleeping room (AOR=3.7, [95% CI: (1.22, 11.39), exposure to x-ray (AOR=9.4,[95% CI: (3.94, 22.82), nonalcohol homemade drinks (AOR=5.4,[95% CI: (1.97, 15.14), use of chemical containers (AOR=3.4, [95% CI: (1.48, 8.23) were determinants of oesophageal cancer.

CONCLUSION

Coffee temperature, coffee drinking volume, porridge consumption temperature, porridge consumption speed, dairy products intake patterns, food cooking place, x-ray exposure, nonalcohol homemade drink, and use of chemical containers were independent determinants of the increased risk of oesophageal cancer in the study community.

Tea in the Morning and Khat Afternoon: Health Threats Due to Khat Chewing

Khat or qat (Catha edulis) is a flowering plant with an Arabic name قات, regularly named as qāt, also is known by various descriptive names, such as Abyssinian tea, Somali tea, Arabian tea, Miraa, Jima, and Kafta in its endemic regions of the Horn of Africa and the Arabian Peninsula. Fresh leaves and tops of khat are chewed or dried and consumed as a tea to attain a state of euphoria and excitement; it also has appetite-reducing effects. Traditionally, khat is used as a socializing habit in Yemen and is also widely cultivated because of its high income. However, in recent years the plant has been reported in England, Wales, Rome, Amsterdam, Canada, Israel, Australia, New Zealand, and the United States. Although it is believed that khat is a relatively low-risk drug, it's associated with an increased risk for various medical complications, including dental and oropharyngeal disease, gastrointestinal, cardiovascular, neuropsychiatric, obstetric, and even can be the cause of cancer. Our goal in this review article is to revise and determine the relationship between chewing khat and its health issues. Additionally, we tried to determine the mechanism involved in health hazards due to consuming the khat.

Oesophageal cancer magnitude and presentation in Ethiopia 2012-2017

The aim of this study was to assess the magnitude, socio-demographic, and clinical characteristics of oesophageal cancer patients in selected referral hospitals of Ethiopia. A retrospective document review was employed in ten referral hospitals in different regions of Ethiopia. A structured data extraction tool was used to extract data from clinical care records of all clinically and pathologically confirmed oesophageal cancer patients who were diagnosed and treated in those hospitals from 2012 to 2017. During the study period, a total of 777 oesophageal cancer cases were identified, and the median age of these patients was 55 years, with an interquartile range of 19. More than half (55.1%, n = 428) of the cases were males, and the majority of them were reported from Oromia (49.9%, n = 388) and Somali (25.9%, n = 202) regional states. The highest numbers of oesophageal cancer cases were recorded in 2016 (23.8%, n = 185), while the lowest were in 2012 (12.6%, n = 98). Eighty per cent of oesophageal cancer cases were diagnosed in later stages of the disease. More than one-fourth (27.0%, n = 210) of patients had surgical procedures where the majority (74.3%, n = 156) required insertion of a feeding tube followed by transhiatal oesophagectomy (10.9%, n = 23). Of the 118 patients for which there was histology data, squamous cell carcinoma (56.7%, n = 67) and adenocarcinoma (36.4%, n = 43) were the predominant histologic type. One-fourth (25.0%, n = 194) of the patients were alive, and more than two-thirds (71.7%, n = 557) of the patients' current status was unknown at the time of the review. In these referral hospitals of Ethiopia, many oesophageal cancer patients presented during later stages of the disease and needed palliative care measures. The number of patients seen in Oromia and Somali hospitals by far exceeded hospitals of the other regions, thus postulating possibly unique risk factors in those geographic areas.

Cancer Incidence and Distribution at a Tertiary Care Hospital in Somalia from 2017 to 2020: An Initial Report of 1306 Cases

Purpose

To determine the type, frequency and distribution of all cancers in Somalia from 2017 to 2020.

Patients and Methods

This retrospective and descriptive study included the review of a total of 5238 pathology reports obtained from the medical records of the Somalia Turkey Recep Tayyip Erdogan Education and Research Hospital. Patient characteristics, lesion localization, and histopathology were recorded. Patients with an unconfirmed cancer diagnosis, borderline tumors, intraepithelial neoplasms and metastatic cancers were excluded from the study. The cases were classified according to gender, age, and organ involvement.

Results

Of the 1306 patients included in the study, 50.9% (n=666) were female and 49.1% (n=640) were male, and the mean age was 51.1±19.4 years. Of the cases, 5.1% (n=67) were pediatric (0–17 years) and 35.8% (n=468) were in the 18–50 years range. The most common cancer was esophageal cancer (EC) for the overall data (n=284; 21.7%) and in both genders. EC peaked in the fifth decade, and the most common histological type was squamous cell carcinoma (n=256; 91.1%). Liver cancer was the second most common cancer overall (n=99; 7.6%) and in men (n=67; 10.5%). Cervical cancer was the second most common cancer among women (n=88; 13.3%) and ranked fourth in terms of overall incidence (n=88; 6.7%). Breast cancer was the third most common overall (n=95; 7.3%) and in women (n= 87; 13.1%).

Conclusion

This study shows that in Somalia, EC is the most common cancer in both genders. These high rates in Somalia suggest that environmental factors and dietary habits may have an effect. To reduce the incidence of EC and prevent its development, the population of Somalia should be educated and effective planning should be undertaken.

Khat chewing in pregnant women associated with prelabor rupture of membranes, evidence from eastern Ethiopia

Introduction

Prelabor rupture of membranes (PROM) is a major factor that affects pregnancy outcome. Results from previous studies have suggested that there is an association between pregnant women, khat chewing and preterm birth, but evidence of association with PROM is sparse. This study therefore aims at identifying association between khat chewing in pregnancy and premature rupture of membranes in eastern Ethiopia.

Methods

A health facility-based cross-sectional study was conducted among 1688 pregnant women who came for delivery service in Harar town, Eastern Ethiopia between June to October in 2016. Data were collected using a pre-tested structured questionnaire and checklist to extract data from the medical record. The association between khat and PROM was examined using logistic regression analysis. A statistical significance was declared at p-value < 0.05.

Results

Of the 1688 pregnant women who participated in the study, 397 had prelabor rupture of the membranes, representing a proportion of 23.5% [(95% CI: (21.5, 25.6%)]. Of these 397 prelabor rupture of the membranes 198 (31.53%) were from Khat chewing mothers and, 199(18.77%) were from non-khat chewing mothers. After controlling for potential confounders, the multivariable logistic regression analysis revealed the odds of PROM was 1.51 times higher among khat chewed pregnant women [AOR = 1.51; 95% CI; (1.11, 2.07)] were had no khat chewing.

Conclusion

This study found a significant association between khat chewing in pregnancy and PROM. Efforts to reduce PROM need to consider prevention of khat chewing in pregnancy. A specific strategy need to protect pregnant women from khat chewing.

Evaluation of Khat (Catha edulis) Use as a Risk Factor of Cancer: A Systematic Review

Background:

Conducting systematic review to evaluate plant use as a risk factor to cancer could be challenging. A systematic and well-balanced method should be applied to accommodate in vivo and in vitro studies to make a final decision. In this article, khat, a recreational plant used in some Arabic and African regions, was employed as an example to systematically determine its relationships to the premalignant and cancerous conditions.

Methods:

Systematic database search was performed to recruit original human, animal or in vitro studies on khat and cancer. Sixteen studies fulfilled the inclusion criteria and subjected to assessment using Risk of Bias (RoB). Office of Health and Translation (OHAT) approach was used to rate the confidence level in the body of evidence. The evidence was integrated to establish the relationships between khat, premalignant conditions and cancer.

Results:

Seven out of eight studies showed that khat causes premalignant oral lesions with moderate evidence level. Four studies showed that khat causes cancer with low evidence level and another three studies showed that khat has anti-cancer effect with moderate to high evidence level. Only one study suggested that khat is unrelated to cancer.

Conclusion:

RoB and OHAT approach are reliable systematic tools to evaluate plant risk to cancer and provide objective and uniform summary regardless of the study type. In conclusion, our pooled analysis did not find a direct relationship between khat and cancer but anti-cancer effect would require to be proofed on human studies.

Systematic review and meta-analysis of esophageal cancer in Africa: Epidemiology, risk factors, management and outcomes

BACKGROUND

Esophageal cancer (EC) is associated with a poor prognosis, particularly so in Africa where an alarmingly high mortality to incidence ratio prevails for this disease.

AIM

To provide further understanding of EC in the context of the unique cultural and genetic diversity, and socio-economic challenges faced on the African continent.

METHODS

We performed a systematic review of studies from Africa to obtain data on epidemiology, risk factors, management and outcomes of EC. A non-systematic review was used to obtain incidence data from the International Agency for Research on Cancer, and the Cancer in Sub-Saharan reports. We searched EMBASE, PubMed, Web of Science, and Cochrane Central from inception to March 2019 and reviewed the list of articles retrieved. Random effects meta-analyses were used to assess heterogeneity between studies and to obtain odds ratio (OR) of the associations between EC and risk factors; and incidence rate ratios for EC between sexes with their respective 95% confidence intervals (CI).

RESULTS

The incidence of EC is higher in males than females, except in North Africa where it is similar for both sexes. The highest age-standardized rate is from Malawi (30.3 and 19.4 cases/year/100000 population for males and females, respectively) followed by Kenya (28.7 cases/year/100000 population for both sexes). The incidence of EC rises sharply after the age of 40 years and reaches a peak at 75 years old. Meta-analysis shows a strong association with tobacco (OR 3.15, 95%CI: 2.83-3.50). There was significant heterogeneity between studies on alcohol consumption (OR 2.28, 95%CI: 1.94-2.65) and on low socioeconomic status (OR 139, 95%CI: 1.25-1.54) as risk factors, but these could also contribute to increasing the incidence of EC. The best treatment outcomes were with esophagectomy with survival rates of 76.6% at 3 years, and chemo-radiotherapy with an overall combined survival time of 267.50 d.

CONCLUSION

Africa has high incidence and mortality rates of EC, with preventable and non-modifiable risk factors. Men in this setting are at increased risk due to their higher prevalence of tobacco and alcohol consumption. Management requires a multidisciplinary approach, and survival is significantly improved in the setting of esophagectomy and chemoradiation therapy.

Prevalence of human papillomavirus and Helicobacter pylori in esophageal and gastroesophageal junction cancer biopsies from a case-control study in Ethiopia

BACKGROUND

Ethiopia lies in the high-risk corridor of esophageal squamous cell carcinoma in East Africa, where individuals with this malignancy often do not report established risk factors, suggesting unidentified etiologies. Here, we report the prevalence of mucosal human papillomavirus (HPV) and of Helicobacter pylori (H. pylori) detection in endoscopy-obtained esophageal and gastroesophageal junction biopsies and in oral cell specimens taken at the time of esophageal cancer diagnosis in a case-control study in Addis Ababa, Ethiopia.

METHODS

DNA extraction was performed from fresh frozen tissue and oral cell pellets obtained with saline solution gargling subsequently fixed with ethanol. Mucosal HPV and H. pylori DNA was detected using highly sensitive assays that combine multiplex polymerase chain reaction and bead-based Luminex technology. The proportions of specimens testing positive were expressed as percentages, with binomial 95% confidence intervals. Agreement of results between tissue biopsy and oral cell specimens was estimated using the kappa statistic. Comparison of study participants' characteristics by test results was done using the Pearson chi-square test.

RESULTS

HPV DNA was detected in 1 of 62 tumor specimens (2, 95% confidence interval (CI): 0-9%), corresponding to HPV16 type. HPV DNA was detected in the oral cavity of 7 cases (11, 95% CI: 5-22%) and 4 of 56 matched healthy controls (7, 95% CI: 2-17%), with multiple HPV types detected. Detection of H. pylori DNA was 55% (95% CI: 42-68%), and 20 of 34 H. pylori-positive specimens (59, 95% CI: 41-75%) were positive for the cagA gene. Agreement of detection rates between tissue and oral cells in cases was poor for HPV and for H. pylori.

CONCLUSIONS

The prevalence of mucosal-type HPV was very low, whereas H. pylori was more commonly detected, with a high proportion testing positive for the pro-inflammatory gene cagA. These novel findings remain to be replicated in larger studies and with the addition of serological determinations to better understand their biological significance in the context of esophageal and gastroesophageal junction cancers.

Hot beverages and oesophageal cancer risk in western Kenya: Findings from the ESCCAPE case-control study

Oesophageal squamous cell carcinoma (ESCC) has markedly high incidence rates in Kenya and much of East Africa, with a dire prognosis and poorly understood aetiology. Consumption of hot beverages-a probable carcinogen to humans-is associated with increased ESCC risk in other settings and is habitually practiced in Kenya. We conducted a case-control study in Eldoret, western Kenya between August 2013 and March 2018. Cases were patients with endoscopically confirmed oesophageal cancer whose histology did not rule out ESCC. Age and sex-matched controls were hospital visitors and hospital out and in-patients excluding those with digestive diseases. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for self-reported drinking temperatures; consumption frequency; mouth burning frequency and hot porridge consumption using logistic regression models adjusted for potential confounders. Drinking temperature association with tumour sub-location was also investigated. The study included 430 cases and 440 controls. Drinkers of 'very hot' and 'hot' beverages (>95% tea) had a 3.7 (95% CI: 2.1-6.5) and 1.4-fold (1.0-2.0) ESCC risk, respectively compared to 'warm' drinkers. This trend was consistent in males, females, never and ever alcohol/tobacco and was stronger over than under age 50 years. The tumour sub-location distribution (upper/middle/lower oesophagus) did not differ by reported drinking temperature. Our study is the first comprehensive investigation in this setting to-date to observe a link between hot beverage consumption and ESCC in East Africa. These findings provide further evidence for the role of this potentially modifiable risk factor in ESCC aetiology.

Cancer epidemiology fieldwork in a resource-limited setting: Experience from the western Kenya ESCCAPE esophageal cancer case-control pilot study

BACKGROUND

Case-control studies remain an important study design for aetiologic research on cancer, particularly when cohorts are not available. In addition to the potential biases inherent in this design, conducting fieldwork in settings with weak health care and information systems for cancer, such as in sub Saharan Africa, confer additional challenges which we present here with the aim to share experience to guide future studies.

METHODS

We undertook a hospital-based case-control study of squamous cell esophageal cancer at the Moi Teaching and Referral Hospital in Eldoret, West Kenya. Cases were recruited at endoscopy and controls from hospital wards, age and gender frequency-matched to cases. Urine, toenails, blood and tumour biopsy were collected and a questionnaire administered.

RESULTS

During this pilot phase, 143 cases and 155 controls were successfully recruited. Complete questionnaire data was obtained through e-data collection. Biospecimen collection was possible with support of an already existing equipped laboratory. We introduce changes made in the main study phase, including on expansion of the control groups to allow to consideration of selection bias.

CONCLUSIONS

Extra attention and funding to train and monitor data quality and biospecimen collection and collaboration of a large group held together by strong leadership are essential. We recommend studies based on regional treatment centres with their more defined catchment areas rather than in the capital cities as referral routes in multi-level health care systems are severely attrition prone.

The African Esophageal Cancer Consortium: A Call to Action

Esophageal cancer is the eighth most common cancer worldwide and the sixth most common cause of cancer-related death; however, worldwide incidence and mortality rates do not reflect the geographic variations in the occurrence of this disease. In recent years, increased attention has been focused on the high incidence of esophageal squamous cell carcinoma (ESCC) throughout the eastern corridor of Africa, extending from Ethiopia to South Africa. Nascent investigations are underway at a number of sites throughout the region in an effort to improve our understanding of the etiology behind the high incidence of ESCC in this region. In 2017, these sites established the African Esophageal Cancer Consortium. Here, we summarize the priorities of this newly established consortium: to implement coordinated multisite investigations into etiology and identify targets for primary prevention; to address the impact of the clinical burden of ESCC via capacity building and shared resources in treatment and palliative care; and to heighten awareness of ESCC among physicians, at-risk populations, policy makers, and funding agencies.

Esophageal cancer male to female incidence ratios in Africa: A systematic review and meta-analysis of geographic, time and age trends

Esophageal squamous cell carcinoma (ESCC) remains the predominant histological subtype of esophageal cancer (EC) in many transitioning countries, with an enigmatic and geographically distinct etiology, and consistently elevated incidence rates in many Eastern and Southern African countries. To gain epidemiological insights into ESCC patterns across the continent, we conducted a systematic review and meta-analysis of male-to-female (M:F) sex ratios of EC age-standardised (world) incidence rates in Africa according to geography, time and age at diagnosis. Data from 197 populations in 36 countries were included in the analysis, based on data from cancer registries included in IARC's Cancer Incidence in Five Continents, Cancer in Africa and Cancer in Sub-Saharan Africa reports, alongside a systematic search of peer-reviewed literature. A consistent male excess in incidence rates overall (1.7; 95% CI: 1.4, 2.0), and in the high-risk Eastern (1.6; 95% CI: 1.4, 1.8) and Southern (1.8; 95% CI: 1.5, 2.0) African regions was observed. Within the latter two regions, there was a male excess evident in 30-39 year olds that was not observed in low-risk regions. Despite possible referral biases affecting the interpretability of the M:F ratios in place and time, the high degree of heterogeneity in ESCC incidence implies a large fraction of the disease is preventable, and directs research enquiries to elucidate early-age exposures among young men in Africa.