Descriptive epidemiology of oral neoplasms in Sudan 1970-1985 and the role of toombak

Epidemiological and histopathological patterns of malignant salivary gland tumors in the Sudanese population

Background

Malignant salivary gland tumors are rare. However, their morphological overlap and difficulty to differentiate benign from malignant makes diagnosing such diseases a challenging task. Geographical variation in distribution of these diseases is well documented in the literature. This study aims to review the histological and epidemiological variations of malignant salivary gland tumors in Sudanese patients considering the new WHO 2022 classification.

Methodology

This retrospective study included malignant salivary gland tumours in our lab spanning from the period of 2014 to 2022. Information about clinical data, habits, geographical distribution, pathological diagnosis, duration and sites of tumors were retrieved from our archives. Equivocal cases were checked by a salivary gland expert. Data analysis was performed using IBM SPSS 29.

Results

This study included 107 cases of malignant salivary gland tumours, representing 54 % of the total number of salivary gland tumours in the lab during that period. 47.7 % of the patients in this study were females and 52.3 % were males, the mean age of patients was 50 ± 15.7 years. (30 %) of the patients were from the central region of the country. The most common malignant salivary gland tumor was the Mucoepidermoid carcinoma accounting for 17 %. The palate was found to be the most common site as 38 % of malignant salivary gland tumors occurred in this site.

Conclusion

The study found a high percentage of salivary gland tumours in the Sudan suggesting geographical differentiation.

Clinical Presentation of Wide Field of Cancerization Associated with Oral Squamous Cell Carcinoma

Background

The late presentation of oral squamous cell carcinoma (OSCC) patients in Sudan, with advanced stages and wide field of cancerization (WFC), has a negative impact on these patients. The present study aimed to investigate the different clinical presentations of mucosal changes in WFC associated with OSCC in Sudanese patients.

Methods

This a prospective longitudinal study of 93 OSCC cases. Tumor's associated field of cancerization was identified and related clinical mucosal changes were described.

Results

Out of the 93 patients, 57 (61.3%) were males and 36 (38.7%) were females. Eighty-two percent of the patients presented with stage IV tumors. Ninety-two patients had multiple sites involved in the oral cavity with overlap of sites involved. The Gingivobuccal mucosa (74.2%) was the most frequent site involved. Eighty-three (89.2%) of the lesions were surrounded by mucosal changes, of them 32 (38%) surrounded by a grizzle (mixed dark and white) discoloration and 21 (26%) were surrounded by a white-smoke discoloration followed by 17 (20%) and 13 (16%) surrounded by cotton-white and Café au lait discolorations, respectively. Forty-four (47.3%) lesions had overlapping presentations and surrounded by erythematous patches.

Conclusion

The present study showed that OSCC patients in Sudan present with advanced lesions, mostly associated with WFC, particularly the Toombak dippers. The different mucosal changes seen in the WFC associated with OSCC in these cases are in accordance with the known five mucosal presentations.

Analysis of Salivary Mycobiome in a Cohort of Oral Squamous Cell Carcinoma Patients From Sudan Identifies Higher Salivary Carriage of Malassezia as an Independent and Favorable Predictor of Overall Survival

Background

Microbial dysbiosis and microbiome-induced inflammation have emerged as important factors in oral squamous cell carcinoma (OSCC) tumorigenesis during the last two decades. However, the “rare biosphere” of the oral microbiome, including fungi, has been sparsely investigated. This study aimed to characterize the salivary mycobiome in a prospective Sudanese cohort of OSCC patients and to explore patterns of diversities associated with overall survival (OS).

Materials and Methods

Unstimulated saliva samples (n = 72) were collected from patients diagnosed with OSCC (n = 59) and from non-OSCC control volunteers (n = 13). DNA was extracted using a combined enzymatic–mechanical extraction protocol. The salivary mycobiome was assessed using a next-generation sequencing (NGS)-based methodology by amplifying the ITS2 region. The impact of the abundance of different fungal genera on the survival of OSCC patients was analyzed using Kaplan–Meier and Cox regression survival analyses (SPPS).

Results

Sixteen genera were identified exclusively in the saliva of OSCC patients. Candida, Malassezia, Saccharomyces, Aspergillus, and Cyberlindnera were the most relatively abundant fungal genera in both groups and showed higher abundance in OSCC patients. Kaplan–Meier survival analysis showed higher salivary carriage of the Candida genus significantly associated with poor OS of OSCC patients (Breslow test: p = 0.043). In contrast, the higher salivary carriage of Malassezia showed a significant association with favorable OS in OSCC patients (Breslow test: p = 0.039). The Cox proportional hazards multiple regression model was applied to adjust the salivary carriage of both Candida and Malassezia according to age (p = 0.029) and identified the genus Malassezia as an independent predictor of OS (hazard ratio = 0.383, 95% CI = 0.16–0.93, p = 0.03).

Conclusion

The fungal compositional patterns in saliva from OSCC patients were different from those of individuals without OSCC. The fungal genus Malassezia was identified as a putative prognostic biomarker and therapeutic target for OSCC.

Feasibility of a Portable Electronic Nose for Detection of Oral Squamous Cell Carcinoma in Sudan

BACKGROUND

Oral squamous cell carcinoma (OSCC) is increasing at an alarming rate particularly in low-income countries. This urges for research into noninvasive, user-friendly diagnostic tools that can be used in limited-resource settings. This study aims to test and validate the feasibility of e-nose technology for detecting OSCC in the limited-resource settings of the Sudanese population.

METHODS

Two e-nose devices (Aeonose™, eNose Company, Zutphen, The Netherlands) were used to collect breath samples from OSCC (n = 49) and control (n = 35) patients. Patients were divided into a training group for building an artificial neural network (ANN) model and a blinded control group for model validation. The Statistical Package for the Social Sciences (SPSS) software was used for the analysis of baseline characteristics and regression. Aethena proprietary software was used for data analysis using artificial neural networks based on patterns of volatile organic compounds.

RESULTS

A diagnostic accuracy of 81% was observed, with 88% sensitivity and 71% specificity.

CONCLUSIONS

This study demonstrates that e-nose is an efficient tool for OSCC detection in limited-resource settings, where it offers a valuable cost-effective strategy to tackle the burden posed by OSCC.

Is toombak a risk factor for oral leukoplakia and oral squamous cell carcinoma ? A systematic review

INTRODUCTION

Toombak is a form of smokeless tobacco that is not well known in Western Society but is widely used by the Sudanese population and many others in the sub-Sahara region. However, unlike other smokeless tobacco products, information on the carcinogenic potential of toombak is scarce. The present review explored any potential epidemiological association between the use of toombak and oral leukoplakia and oral squamous cell carcinoma (OSCC).

METHODS

Databases including the Web of Science, SCOPUS, EMBASE and PubMed were searched for literature on the potential association between toombak and oral leukoplakia and OSCC. The search also included grey literature. The search period extended from 1990 to 2018. Following data mining, the study selection was conducted by two reviewers independently.

RESULTS

Eight studies that satisfied the inclusion criteria were included. Based on these results, there was a threefoldto sevenfold increased risk of developing the oral leukoplakia and oral squamous cell carcinoma among toombak users compared with non-users.

CONCLUSION

Based on the results of the systematic review, there is a strong epidemiological evidence to suggest toombak to be a major risk factor for both oral leukoplakia and OSCC. Further studies are necessary to evaluate the molecular pathway of toombak-induced oral carcinogenesis.

Molecular alterations associated with chronic exposure to cigarette smoke and chewing tobacco in normal oral keratinocytes

Tobacco usage is a known risk factor associated with development of oral cancer. It is mainly consumed in two different forms (smoking and chewing) that vary in their composition and methods of intake. Despite being the leading cause of oral cancer, molecular alterations induced by tobacco are poorly understood. We therefore sought to investigate the adverse effects of cigarette smoke/chewing tobacco exposure in oral keratinocytes (OKF6/TERT1). OKF6/TERT1 cells acquired oncogenic phenotype after treating with cigarette smoke/chewing tobacco for a period of 8 months. We employed whole exome sequencing (WES) and quantitative proteomics to investigate the molecular alterations in oral keratinocytes chronically exposed to smoke/ chewing tobacco. Exome sequencing revealed distinct mutational spectrum and copy number alterations in smoke/ chewing tobacco treated cells. We also observed differences in proteomic alterations. Proteins downstream of MAPK1 and EGFR were dysregulated in smoke and chewing tobacco exposed cells, respectively. This study can serve as a reference for fundamental damages on oral cells as a consequence of exposure to different forms of tobacco.

School workers' knowledge, attitude and behaviour related to use of Toombak: a cross sectional study from Khartoum state, Sudan

BACKGROUND

Toombak is a form of smokeless tobacco (SLT) that is locally made and consumed in Sudan and contains several carcinogenic elements. Use of Toombak has been etiologically linked to various oral diseases including oral cancer. This study aimed to obtain baseline information about the Toombak use among Sudanese school workers, as well as their knowledge about Toombak related health hazards and attitude towards their role in Toombak control. In addition, this study assessed the availability and effectiveness of control policies and preventive practices in the schools.

METHODS

A cross-sectional school-based study using one-stage stratified random sampling procedure; four schools were selected randomly from each of seven localities. A total of 239 school workers' were recruited (census) from the selected schools in Khartoum State, Sudan.

RESULTS

Of the school workers, 63% (147) were ≤40 years, half were females and 79.2% (187) were teachers. A total of 9.6% (22) school workers confirmed ever use of Toombak and the percentage of daily users amounted to 64.7% (11). Moreover, 76.2% (16) of ever Toombak users were ≥40 years and all of them were males (p < 0.001). Most of the school workers reported good knowledge, positive attitude towards their role in Toombak control and good preventive practice. Female school workers were more likely to report positive attitude towards their role in Toombak control (p < 05), and to report good knowledge. Those reporting good preventive practice in schools reported good knowledge more than two times than their counterpart (p < 0.001). Age was the strongest predictor of ever Toombak use among school workers (p < .001).

CONCLUSIONS

The use of Toombak among school workers was associated with poor knowledge, negative attitude towards their role in Toombak control and poor preventive practice, Therefore, school workers use of Toombak may reduce their motivation and use of their potential in the prevention of a major health problem caused by Toombak use and affects their role model behaviour. On the other hand, school workers engagement with preventive practices in schools' was associated with good knowledge which in turn empowers their positive attitude towards their role in Toombak control.

Retrospective analysis of biopsied oral and maxillofacial lesions in South-Western Saudi Arabia

Objectives:

To report the prevalence and types of biopsied oral and maxillofacial lesions (OMLs) in South-Western (Jazan Province) region, Kingdom of Saudi Arabia (KSA).

Methods:

This retrospective study was based on the retrieval of clinicopathological data for a period of 6 years between January 2009 and December 2014. These data were obtained between October 2014 and June 2015 from the histopathology records of King Fahad Central Hospital, Jazan, KSA, which is the only referral center for biopsy services.

Results:

Out of the 32149 biopsies received, 714 (2.2%) were OMLs. The age ranged from 0 (neonatal) to 100 years, with a mean age of 46.8±23.4 and a male-to-female ratio of 1:1.3. The tongue was the most common site for OMLs and for malignant neoplasms, in particular. The most common category was malignant neoplasm (38.7%), followed by inflammatory lesions (16.5%). Oral malignancies accounted for 15.8% of all malignancies. Oral squamous cell carcinoma (OSCC) (36.1%) was the most frequent type, followed by pyogenic granuloma and mucocele (7% each). Shammah-associated OSCC and epithelial dysplasia were twice as common in females.

Conclusion:

The number of non-malignant OMLs was much lower than expected in comparison to oral malignancies. This difference can likely be explained by the fact that the biopsies were taken only when malignancy was suspected. The higher rate of OSCC reported from this region is attributed to shammah usage. This study emphasizes the importance of biopsy services for all OMLs and the prevention of shammah use.

Global incidence of oral and oropharynx cancer in patients younger than 45 years versus older patients: A systematic review

Head and neck squamous cell carcinoma (HNSCC) is typically regarded as a disease of elderly people. However, increasing numbers of patients worldwide with HNSCC at younger age (defined as <45 years old) have been reported in recent years. To assess geographical variations and trends worldwide in incidence of oral and oropharyngeal cancer in young patients, a systematic review was conducted in PubMed and Google scholar databases from 1975 to June 2016. Seventy-eight studies were selected for further study. Nineteen population-based studies on incidence rate were available from 13 countries, showing a prominent increase over time except for the Netherlands. A notable rise of oral (mobile) tongue cancer among white women and oropharyngeal cancer in white men was observed. Data suggest that cancer in young patients may be a distinct clinical entity and characterised by different aetiology and pathogenesis. Additionally, the relative proportion of oral and oropharyngeal cancer in young patients to total incidence revealed a significant difference between estimates from North America (5.5%) and both Africa (17.2%) and Middle East (14.5%). It is concluded that (i) a rising trend in oral and oropharynx cancers is observed in young patients worldwide; (ii) incidence studies should properly define outcomes in age cohorts and use a consensus cut-off for young patients; (iii) more population-based studies should be performed in non-Western regions to get accurate global measures of incidence for these cancers in young subpopulations and (iv) there is an urge to identify new aetiological factors in these young patients.

Differences in the Bacteriome of Smokeless Tobacco Products with Different Oral Carcinogenicity: Compositional and Predicted Functional Analysis

Smokeless tobacco (ST) products vary significantly in their oral carcinogenicity. Much is known about the differences in the chemical, but not the bacterial, constituents of these products. In this study, we explored the composition and function of the bacteriome in ST products from four countries using quantitative polymerase chain reaction (qPCR) and 16S rRNA-based next generation sequencing. The bacterial load (16S rRNA copies/gram) was lowest in Swedish snus (3.4 × 10⁶) and highest in Yemeni shammah (6.6 × 10¹¹). A total of 491 species-level taxa, many of which are potentially novel, belonging to 178 genera and 11 phyla were identified. Species richness and diversity were highest for Swedish snus and lowest for Yemeni shammah. Bacillus, Paenibacillus, and Oceanobacillus spp. were the most abundant in American snuff; species of Pseudomonas, Massilia, Propionibacterium, Puniceispirillum, and Gloeothece predominated in Swedish snus. In Sudanese toombak, Facklamia, Desemzia, Atopostipes, and Lysinibacillus spp. accounted for the majority of the bacteriome. Yemeni shammah exclusively contained Bacillus spp. Functional prediction by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) showed that genes encoding cadmium/zinc and nickel transport systems were enriched in the presumptively “high carcinogenicity” products. The bacteriome of ST products thus differed qualitatively, quantitatively, and functionally. The relevance of these differences, particularly with respect to nickel and cadmium, to oral carcinogenesis warrants further investigation.

Relative Frequency of Oral Malignancies and Oral Precancer in the Biopsy Service of Jazan Province, 2009-2014

BACKGROUND

The objective of this study was to report the types and relative frequency of oral malignancies and precancer in the Jazan region of Saudi Arabia during the period 2009-2014.

MATERIALS AND METHODS

Pathology reports were retrieved from the archives of Histopathology Department, King Fahd hospital in Jazan. Demographic data on tobacco habits, clinical presentation and histologic grading of oral precancer and cancer cases were transcribed from the files.

RESULTS

303 (42.7%) oral pre-malignant and malignant cases were found out of 714 oral biopsy lesions. A pathology diagnosis of squamous cell carcinoma (85.1%) was most frequent, followed by premalignant lesions/epithelial dysplasia (8.6%), verrucous carcinoma (3.3%) and malignancy of other histological types (3%) such as ameloblastic carcinoma, salivary gland malignancy and sarcomas. Oral squamous cell carcinoma was predominant in females with a male to female ratio of 1:1.9. Patient age ranged from 22 to 100 years with a mean of 65±13.9. Almost 44.6% of oral cancer had occurred after 65 years of age. Only 16.3% cases were reported in patients younger than 50 years, predominantly females. The majority of female patients had the habit of using shammah with a long duration of usage for more than 45 years. Bucco- alveolar mucosa (52.3%) was the common site of involvement followed by tongue/ floor of the mouth (47.7%) and clinically presented mostly as ulceration/swelling clinically. Moderately differentiated tumours (53.9%) were common followed by well differentiated (32.2%) and poorly differentiated tumours (5.8%). The prevalence of oral verrucous carcinoma (3.3%) was comparatively low with an equal distribution in both males and females. Both bucco-alveolar mucosa and tongue were predominantly affected. Oral precancer/epithelial dysplasia (8.6%) was common in females with a shammah habit. Bucco-alveolar mucosa was commonly involved and clinically presented mostly as white/red patches. Most cases were mild followed by moderate and severe dysplasia. Tumours of other histological types (3%) include 1 ameloblastic carcinoma, 3 malignant salivary gland tumours and 5 sarcomas.

CONCLUSIONS

In this study, it was found that oral cancers reported in the pathology service to be a common occurrence. This study reconfirms previous reports of the high burden of oral cancer in this population This indicates that conventional preventive programs focused on oral cancer are in need of revision. In addition, further research into identifying new risk factors and molecular markers for oral cancer are needed for screening high risk individuals.

Oral malignant melanoma: a rare case with unusual clinical presentation

Primary Oral malignant melanoma is a rare tumor with an indigent prognosis. This is a case report of 47-year-old Sudanese female diagnosed as Oral malignant melanoma of the mandible with an unusual pattern of growth and clinical presentation. Furthermore, a possibility of intraosseous origin is suggested.

Review: Head and neck squamous cell carcinoma in sub-Saharan Africa

AIM

Review the literature from 1990 to 2013 to determine known anatomic sites, risk factors, treatments, and outcomes of head and neck squamous cell carcinoma (HNSCC) in sub-Saharan Africa.

METHODS

Using a systematic search strategy, literature pertaining to HNSCC in sub-Saharan Africa was reviewed and patient demographics, anatomic sites, histology, stage, treatment, and outcomes were abstracted. The contributions of human immunodeficiency virus (HIV), human papillomavirus (HPV) and behavioural risk factors to HNSCC in the region were assessed.

RESULTS

Of the 342 papers identified, 46 were utilized for review, including 8611 patients. In sub-Saharan Africa, the oropharyngeal/oral cavity was found to be the most common site, with 7750 cases (90% of all cases). Few papers distinguished oropharyngeal from oral cavity, making identification of possible HPV-associated oropharyngeal squamous cell carcinoma (SCC) difficult. SCC of the nasopharynx, nasal cavity, or paranasal sinuses was identified in 410 patients (4.8% of all cases). Laryngeal SCC was found in 385 patients (4.5% of all cases), and only 66 patients (0.8% of all cases) with hypopharyngeal SCC were identified. In 862 patients with data available, 43% used tobacco and 42% used alcohol, and reported use varied widely and was more common in laryngeal SCC than that of the oropharyngeal/oral cavity. Toombak and kola nut use was reported to be higher in patients with HNSCC. Several papers reported HIV-positive patients with HNSCC, but it was not possible to determine HNSCC prevalence in HIV-positive compared to negative patients. Reports of treatment and outcomes were rare.

CONCLUSIONS

The oropharyngeal/oral cavity was by far the most commonly reported site of HNSCC reported in sub-Saharan Africa. The roles of risk factors in HNSCC incidence in sub-Saharan Africa were difficult to delineate from the available studies, but a majority of patients did not use tobacco and alcohol.

Cytogenetic significance of chromosome 17 aberrations and P53 gene mutations as prognostic markers in oral squamous cell carcinoma

BACKGROUND

Cytogenetic analysis has detected an accumulation of genetic lesions in oral cancers. Numerical changes in chromosome 17 might be associated with an up-regulation of p53 gene, and could contribute to critical events in carcinogenesis. The aim of this study was to reveal possible correlations between the numerical aberrations of chromosome 17, deletion or amplification of the P53 gene and histological grading in patients with oral squamous cell carcinoma (OSCC).

METHODS

This study was performed retrospectively on anonymous forty paraffin embedded specimens diagnosed with a primary OSCC. Sections were prepared for p53 immunohistochemical staining and FISH technique evaluation.

RESULTS

All studied cases showed a positive nuclear staining with different indices for the p53 protein. Furthermore, statistical analysis showed a significant difference between all histological types of OSCC. In term of P53 immunoreactivity well differentiated OSCC showed the highest, whereas poorly differentiated showed weakest. Regarding chromosome 17 aberrations and p53 gene mutations, Spearman correlation test revealed a statistical significant positive correlation between chromosome 17 abnormalities and p53 gene mutations as well as with the immunohistochemical expression of p53 proteins. Moreover, the positive association between p53 gene mutations and the expression of p53 protein was statistically significant.

CONCLUSION

In the light of the previous findings, we concluded that numerical aberrations of chromosome 17 and p53 gene mutations as well as expression of p53 protein have enormous influence on various cellular processes including differentiation and carcinogenesis. Such knowledge provides an easy and simplified approach to prognosis predilection for OSCC.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2015_232 .

Viral infection and oral habits as risk factors for oral squamous cell carcinoma in Yemen: a case-control study

OBJECTIVE

The role of qat chewing, tobacco (shammah) dipping, smoking, alcohol drinking, and oral viral infection as risk factors for oral squamous cell carcinoma (OSCC) in Yemen was assessed.

STUDY DESIGN

A total of 60 cases of OSCC and 120 age- and gender-matched controls were analyzed with respect to demographic data, history of oral habits, and the presence of human papillomavirus (HPV)-16, HPV-18, or Epstein-Barr virus (EBV) as determined by Taqman quantitative polymerase chain reaction. Logistic regression analysis was used to identify independent predictors of the disease.

RESULTS

Shammah use was the only risk factor for OSCC, with an odds ratio of 12.6 (CI, 3.3-48.2) and 39 (CI, 14-105) for the ex-users and current users, respectively. The association of shammah use alone with OSCC exceeded that of shammah use in combination with qat chewing, smoking, or both. EBV infection, smoking, and qat chewing showed no association with OSCC, while neither HPV-16 nor HPV-18 were detected in any sample.

CONCLUSIONS

Shammah use is a major risk factor for oral cancer in Yemen.

A Case-Control Study of Oral Epithelial Proliferative Markers among Sudanese Toombak Dippers Using Micronuclei Assay, Argyrophilic Nucleolar Organizer Region, Papanicolaou and Crystal Violet Methods

The use of Toombak has been reported to play a major role in the etiology of oral cancer in Sudan. The cellular proliferative activity on the oral epithelium of 210 Toombak dippers was assessed by applying the micronuclei frequency, mean argyrophilic nucleolar organizer region (AgNOR) counts, Papanicolaou method, and 1% crystal violet stain. Participants were divided into 3 groups: 200 were apparently healthy individuals, 100 were Toombak users (cases), 100 were non-tobacco users (control) and 10 were patients with oral squamous cell carcinomas. Cytological atypia was identified among 4 (4%). Toombak users and was not found among the control group (P<0.04). The micronuclei frequencies were higher in Toombak users (1.026) than in the control group (0.356) (P<0.0001). The mean AgNOR counts in Toombak users (2.423) were higher than control group (1.303) (P<0.0001). Neither Toombak users nor control group showed mitotic figures in 1% crystal violet method. The results of this research showed that Toombak dipping is a high risk factor for increase in the cellular proliferation in the oral mucosa. The cytological proliferative marker methods used are useful for screening Toombak users.

Survey on knowledge and attitudes related to the relation between tobacco, alcohol abuse and cancer in the northern state of Sudan

BACKGROUND

The aim of this study was to determine the epidemiology of tobacco smoking, toombak dipping and alcohol consumption as risk factors for cancer in the adult population of the northern state of Sudan.

MATERIALS AND METHODS

A cross-sectional survey from March to April 2010, covering 963 adults, was performed.

RESULT

Only 207 had responded, and the male female prevalence was 20.8% and 0.73%. Out of 207 respondents, 29.5% had smoked tobacco in their lifetime, 38% were toombak dippers, while 14% were consumers of alcoholic beverages.

CONCLUSIONS

The prevalence of toombak dipping was higher than tobacco smoking among the adult population in the northern state of Sudan. Female participation in tobacco and alcohol related studies was found to suffer from major obstacles since these habits are considered as social stigma. Appreciation of the full impact of smoking on population health will definitely make a major contribution to improvement of the poor public health situation in Sudan.

The combined effects of single-nucleotide polymorphisms, tobacco products, and ethanol on normal resting blood mononuclear cells

INTRODUCTION

Tobacco and ethanol consumption are crucial factors in the development of various diseases including cancer. In this investigation, we evaluated the combined effects of a number of single nucleotide polymorphisms (SNPs), with ethanol and tobacco products on healthy individuals.

METHODS

Pure nicotine, cigarette smoke extract, and Swedish snuff (snus) extract were used. The effects were examined by means of in vitro cell cycle progression and cell death of peripheral blood mononuclear cells (PBMCs) obtained from healthy donors.

RESULTS

After 3 days, in vitro, resting PBMCs entered the S and G2 stage in the presence of 100 µM nicotine. The PBMCs only proceeded to S stage, in the presence of 0.2% ethanol. The nicotine- and ethanol-induced normal cell cycle progression correlated to a number of SNPs in the IL12RB2, Rad 52, XRCC2, P53, CCND3, and ABCA1 genes. Certain SNPs in Caspases 8, IL12RB2, Rad 52, MMP2, and MDM2 genes appeared to significantly influence the effects of EtOH-, snus-, and snus + EtOH-induced cell death. Importantly, the highest degree of cell death was observed in the presence of smoke + EtOH. The amount of cell death under this treatment condition also correlated to specific SNPs, located in the MDM2, ABCA1, or GASC1 genes.

CONCLUSIONS

Cigarette smoke in combination with ethanol strongly induced massive cell death. Long-term exposure to smoke and ethanol could provoke chronic inflammation, and this could be the initiation of disease including the development of cancer at various sites.

Immunophenotyping of HPV Types 16 and 18 among Sudanese Patients with Oral Lesions

OBJECTIVE

The aim of this study was to screen patients with oral lesions for the presence of Human Papilloma Virus (HPV) types 16 and 18.

METHODS

Sixty patients aged between 11-80 years with a mean age of 46 years were examined using immunohistological techniques. All samples were retrieved from RICK during the period from August 2009 to August 2010. Out of 60 patients, 50 had Oral Squamous Cell Carcinomas (OSCCs) and the remaining ten had benign oral lesions, included as internal control.

RESULTS

Of the 50 patients with OSCCs, 10 (20%) showed positive immunohistochemical results for HPV types 16 and 18 of which 50% were detected among males and 50% were demonstrated among females. The ten positive findings were Immunophenotyped as follows: five were positive with HPV type 16, four with type 18 and one was positive for HPV types 16 and18. All patients with benign oral lesions were negative for HPV immunohistochemistry.

CONCLUSION

The study suggests the role of HPV 16 and 18 in the etiology of oral cancers in different parts of Sudan. However, the use of molecular techniques such as PCR are needed to confirm the results of immunohistochemistry in the role of the HPV in developing of OSCC in Sudan.

Cancer in the Sudan: an overview of the current status of knowledge on tumor patterns and risk factors

The Sudan, the largest and most diverse country in Africa, is experiencing a growing cancer problem, but little is presently known on tumor patterns, cancer epidemiology and ethnic or environmental cancer risk factors. We review here the current status of knowledge, summarizing data from local and international publications as well as primary information from the only two cancer hospitals of the country, both located in Central Sudan (Khartoum and Wad Medani). We provide frequencies reported for cancers detected in adults and children, and summarize studies on specific cancer types, as well as information on risk factors that most likely impact on tumor patterns.

Oral mucosal lesions in skin diseased patients attending a dermatologic clinic: a cross-sectional study in Sudan

Background

So far there have been no studies focusing on the prevalence of a wide spectrum of oral mucosal lesions (OML) in patients with dermatologic diseases. This is noteworthy as skin lesions are strongly associated with oral lesions and could easily be neglected by dentists. This study aimed to estimate the frequency and socio-behavioural correlates of OML in skin diseased patients attending outpatient's facility of Khartoum Teaching Hospital - Dermatology Clinic, Sudan.

Methods

A cross-sectional hospital-based study was conducted in Khartoum from October 2008 to January 2009. A total of 588 patients (mean age 37.2 ± 16 years, 50.3% females) completed an oral examination and a personal interview of which 544 patients (mean age 37.1 ± 15.9 years, 50% females) with confirmed skin disease diagnosis were included for further analyses. OML were recorded using the World Health Organization criteria (WHO). Biopsy and smear were used as adjuvant techniques for confirmation. Data were analysed using the Statistical Package for Social Science (Version 15.0.1). Cross tabulation and Chi-square with Fisher's exact test were used.

Results

A total of 438 OML were registered in 315 (57.9%, males: 54.6% versus females: 45.6%, p < 0.05) skin diseased patients. Thus, a certain number of patients had more than one type of OML. Tongue lesions were the most frequently diagnosed OML (23.3%), followed in descending order by white lesions (19.1%), red and blue lesions (11%) and vesiculobullous diseases (6%). OML in various skin diseases were; vesiculobullous reaction pattern (72.2%), lichenoid reaction pattern (60.5%), infectious lesions (56.5%), psoriasiform reaction pattern (56.7%), and spongiotic reaction pattern (46.8%). Presence of OML in skin diseased patients was most frequent in older age groups (62.4% older versus 52.7% younger, p < 0.05), in males (63.2% males versus 52.6% females, p < 0.05), patients with a systemic disease (65.2% with systemic versus 51.9% without systemic disease, p < 0.05) and among current users of smokeless tobacco (toombak) (77% current use versus 54.8% no use, p < 0.00).

Conclusions

OML were frequently diagnosed in skin diseased patients and varied systematically with age, gender, systemic condition and use of toombak. The high prevalence of OML emphasizes the importance of routine examination of oral mucosa in a dermatology clinic.

Adverse effects of Sudanese toombak vs. Swedish snuff on human oral cells

BACKGROUND

The high incidence of oral cancer in Sudan has been associated with the use of toombak, the local type of smokeless tobacco. However, its specific effects on human oral cells are not known. We aimed to investigate the effects of toombak on primary normal human oral keratinocytes, fibroblasts, and a dysplastic oral keratinocytic cell line, and to compare them with the effects induced by Swedish snuff.

METHOD

Aqueous extracts were prepared from moist toombak and Swedish snuff and added in serial dilutions on in vitro monolayer cultured cells. Cell viability, morphology and growth, DNA double-strand breaks (gammaH2AX staining), expression of phosphatidylserine (Annexin V staining), and cell cycle were assessed after various exposure time periods.

RESULTS

Significant decrease in cell number, occurrence of DNA double-strain breaks, morphological and biochemical signs of programmed cell death were detected in all oral cell types exposed to clinically relevant dilutions of toombak extract, although to a lesser extent in normal oral fibroblasts and dysplastic keratinocytes. G2/M-block was also detected in normal oral keratinocytes and fibroblasts exposed to clinically relevant dilutions of toombak extract. Swedish snuff extract had less adverse effects on oral cells, mainly at non-clinically relevant dilutions.

CONCLUSION

This study indicates a potential for toombak, higher than for Swedish snuff, to damage human oral epithelium. Dysplastic oral keratinocytes were less sensitive than their normal counterparts, suggesting that they might have acquired a partially resistant phenotype to toombak-induced cytotoxic effects while still being prone to DNA damage that could lead to further malignant progression.

Assessment of cytological atypia, AgNOR and nuclear area in epithelial cells of normal oral mucosa exposed to toombak and smoking

The purpose of this study was to assess cellular proliferative activity of clinically healthy oral mucosal epithelial cells of toombak dippers and smokers by means of AgNOR counts and nuclear areas via nuclear morphometry. Smears were collected from normal-appearing mouth floor mucosa and tongue of 75 toombak dippers, 75 smokers and 50 non-tobacco users between the ages of 20 and 70 with a mean age of 36 years. AgNORs were counted in the first 50 well-fixed, nucleated squamous cells and nuclear areas were calculated via microscopic stage micrometer. Cytological atypia was ascertained in 6 tobacco users and could not be ascertained in non-tobacco users. Statistically mean AgNOR numbers per nucleus in the non-tobacco users (2.45±0.30) was lower than the toombak dippers (3.081±0.39, p<0.004), and the smokers (2.715±0.39, p<0.02), and mean nuclear areas of epithelial cells of toombak dippers (6.081±0.39, p<0.009) and smokers (5.68±10.08, p<0.01) was also significantly higher than non-smokers (5.39±9.4). The mean number of nuclei having more than 3 AgNORs was 28%, 19% and 7% in toombak dippers, smokers and non-tobacco users, respectively. These findings support the view that toombak dipping and smoking are severe risk factors for oral mucosal proliferative lesions and exfoliative cytology is valid for screening of oral mucosal lesions.

Global epidemiology of oral and oropharyngeal cancer

This review presents data on incidence, mortality, survival and trends in cancers of the lip, oral cavity and oropharynx using available recent data sources around the world. Oral and pharyngeal cancer, grouped together, is the sixth most common cancer in the world. The review focuses primarily on several high-risk countries in an attempt to gain insight into the geographic variations in the incidence of this cancer in the globe and to relate the high incidence in some populations to their life style. With an estimated half a million cases around the globe and the rising trends reported in some populations, particularly in the young, urgent public health measures are needed to reduce the incidence and mortality of oral and oropharyngeal cancer.

Expression profile of the S100 gene family members in oral squamous cell carcinomas

BACKGROUND

Several of the S100 gene members have been reported to be differentially expressed in many human pathological conditions, in particular, the malignancies. Identification and quantification of the differentially expressed S100 gene members in oral squamous cell carcinoma (OSCC) might facilitate their use as potential diagnostic and/or prognostic markers or targets for therapy.

METHODS

we examined the expression profile of 16 members of the S100 gene family at the mRNA level by semiquantitative reverse transcription-polymerase chain reaction (sRT-PCR) in 27 cases of OSCCs/their pair-wised normal controls obtained from Sudanese patients, and confirmed the sRT-PCR results by performing quantitative real time-polymerase chain reaction (qRT-PCR) for 6 of the 16 genes examined.

RESULTS

With sRT-PCR, 4 (25%; S100A4, S100A6, S100A8, S100A14) out of the 16 S100 gene members examined were found to be significantly down-regulated (P < 0.05) in the tumors compared to the normal controls. None of the S100 gene members examined were found to be significantly up-regulated in the tumors. qRT-PCR results confirmed the significant down-regulation of the S100A4, S100A6, and S100A14 genes in the tumors examined.

CONCLUSION

S100 gene family members might play an important role in the pathogenesis of the OSCCs examined. Findings of the present work warrant in-depth studies of the S100 gene family members, in particular, the S100A4, S100A6, S100A8, and S100A14 to further understand their possible role(s) in OSCC tumorigenesis.

Smokeless tobacco and cancer

Use of smokeless tobacco products is common worldwide, with increasing consumption in many countries. Although epidemiological data from the USA and Asia show a raised risk of oral cancer (overall relative risk 2.6 [95% CI 1.3-5.2]), these are not confirmed in northern European studies (1.0 [0.7-1.3]). Risks of oesophageal cancer (1.6 [1.1-2.3]) and pancreatic cancer (1.6 [1.1-2.2]) have also increased, as shown in northern European studies. Results on lung cancer have been inconsistent, with northern European studies suggesting no excess risk. In India and Sudan, more than 50% of oral cancers are attributable to smokeless tobacco products used in those countries, as are about 4% of oral cancers in US men and 20% of oesophageal and pancreatic cancers in Swedish men. Smokeless tobacco products are a major source of carcinogenic nitrosamines; biomarkers of exposure have been developed to quantify exposure as a framework for a carcinogenesis model in people. Animal carcinogenicity studies strongly support clinical results. Cancer risk of smokeless tobacco users is probably lower than that of smokers, but higher than that of non-tobacco users.

Prevalence of oral cancer and potentially malignant lesions among shammah users in Yemen

The purpose of this study was to assess the prevalence of oral precancerous lesions and squamous cell carcinoma (OSCC) in Yemeni users of shammah, a traditional smokeless tobacco habit known in the Arabian Peninsula. The study group comprised 199 male and one female shammah users who were interviewed via a standardised questionnaire and clinically examined in 48 Yemeni villages and cities. Cases with oral leukoplakia (OL) or mucosal burns (MB) were compared with users without any lesion. MB were detected in 31%, of which 46.8% were located on the tongue or floor of the mouth, and OL in 27%, of which 59.2% were located in the same region. In addition, two cases (1%) of apparent OSCC were identified. Statistically significant increased OR (95% CI) of OL were (a) 6.91 (2.66-17.95) for an average duration of the respective shammah application >5min.; (b) 4.90 (1.99-12.08) for a daily frequency of those applications >10; and (c) 4.22 (1.43-12.43) for a daily duration >6h of chewing qat, also a traditional habit in Yemen. Likewise, decreased OR were (a) 0.39 (0.18-0.85) for rinsing the mouth after the shammah application; (b) 0.36 (0.17-0.78) for successful attempts to stop the use in the past; and (c) 0.26 (0.09-0.72) for existing knowledge about the carcinogenicity of shammah that was present in only 19% overall. In conclusion, evidence was shown for a significant association between the prevalence of OL and the daily duration of shammah application in a dose-dependent manner. An appropriate public health program might help to reduce this potential OSCC burden in shammah users.

Squamous cell carcinoma of the oral cavity, maxillary antrum and lip in a Zimbabwean population: A descriptive epidemiological study

Squamous cell carcinoma accounts for approximately 90% of oral malignancies. The objective of this study was to document the gender, age, sub-site distribution and histologic differentiation of squamous cell carcinoma of the oral cavity, maxillary antrum and lip in a Zimbabwean population. Hospital records of patients with a histologic diagnosis of squamous cell carcinoma of the oral cavity, maxillary antrum and lip seen at Harare Central Hospital and Parirenyatwa Hospital in Zimbabwe during the period January 1982-December 1991 were reviewed. 20.8% (n = 358/1723) were squamous cell carcinoma of the oral cavity, maxillary antrum and lip. Age ranged from 3 to 70years with a 2:1 male:female ratio. Peak incidence in both sexes were in the 41-50 and 51-60years age groups. Sub-site distribution was mandibular gingiva 18.4%, tongue 17.9%, floor of the mouth 16.2%, maxillary gingiva 9.2%, buccal mucosa 9.2%, maxillary antrum 12.6%, hard palate 7.8%, soft palate 4.8%, lower lip 2.8% and upper lip 1.1%. 64.8% were well differentiated, 24.8% moderately differentiated and 10.4% poorly differentiated. The mandibular gingiva, floor of the mouth and tongue were most commonly affected. Lip squamous cell carcinoma was uncommon. Well-differentiated squamous cell carcinoma was most common in the 41-60 years age group.

Intra-oral carcinomas in Maiduguri, north-eastern Nigeria

OBJECTIVE

To document the pattern of intra-oral carcinomas diagnosed in north-eastern Nigeria.

DESIGN AND SETTING

A retrospective clinical and histopathological review seen in a tertiary care hospital (January 1987-December 2002).

MATERIALS AND METHODS

Information on socio-demographic characteristics of patients and details of cancer management were retrieved from the files and histopathology records of cases diagnosed at the hospital.

RESULTS

A total of 378 biopsies, 317 primary cancers including 279 carcinomas of the head and neck were diagnosed during the study period. Intra-oral carcinomas constitute 43 (15.4%) of all head and neck carcinomas reported, with no occurrence in children. The overall mean age of occurrence was 51.2 +/- 15.6 years (male = 56.2 +/- 13.7 years; females = 47.5 +/- 16.2 years) and an overall male-female ratio of 3:4. Carcinomas were commonly reported in the palate 19 (44.2%) and lip six (13.9%) and floor of mouth four (9.3%). Squamous cell carcinoma 28 (65.1%), adenoidcystic carcinoma seven (16.3%) and mucoepidermoid carcinoma five (11.6%) were the commonly reported carcinomas. Squamous cell carcinoma was the most common carcinoma in all sites, in the sixth decade of life, of equal gender distribution and commonly reported in users of kola nuts and tobacco. The occupation of patients diagnosed with oral carcinoma and squamous cell carcinoma was farming (50%, 61.5%). All the staged cancers patients (n = 7) reported in the late stages (III/IV) of the disease. The mean interval between symptoms and presentation for the different carcinomas ranged between 9 and 25 months, with the least interval reported for mucoepidermoid carcinoma.

CONCLUSIONS

Squamous cell carcinoma was the most common oral carcinoma, commonly reported in the palate, among farmers and in the sixth decade of life. Its occurrence in under 40 year olds is three to six times greater than reported for the USA and Europe and may be associated with poor diet and the habitual use of kola nuts and tobacco. The survival rates of patients diagnosed with intra-oral carcinomas, although not available, would be expectedly low in view of the prognostic indicators recorded in this series. The routine oral cancer screening of each patient, and counselling of patients with high-risk habits, by dentists is recommended to improve the prognosis of the disease.

Oral malignant neoplasia: a survey of 428 cases in two Zimbabwean hospitals

A review of oral malignant neoplasms biopsies accessioned in the pathology services of Harare Central Hospital and Parirenyatwa Hospital, Harare, Zimbabwe, during the 10year period January 1982 to December 1991 was carried out. Clinical records of 428 patients with histologically diagnosed oral malignant neoplasms by ICD-O type and site (COO.O-CO6.9) were retrieved and analyzed for gender, age, history of tobacco and alcohol usage, neoplastic type and histologic differentiation of squamous cell carcinoma (8000/3). Oral malignant neoplasms constituted 24.8% (n = 428) of the 1723 biopsies accessioned in the department during this period. There was a male to female ratio of 1.9:1, with lesions being most common in the 41-60 year age group. Squamous cell carcinoma, (8070/3) 73.1%, was the predominant oral malignancy most common in the 61-70 year age group with 21.1% on the mandibular gingivae (CO3.1), 20.5% on the tongue (CO1.9-CO2.9), 18.5% on the floor of the mouth (CO4.9) and 10.5% each on the maxillary gingivae (CO3.O) and buccal mucosa (CO6.O). The hard palate (CO5.9) had 9% of the lesions. Lip malignancy (COO-COO.9 and C44.0), inclusive of mucosa of lip, vermilion and skin, constituted 3.3% and minor salivary gland (CO6.9) malignancy (M-8940/3) 4.9%. The remaining oral malignancies, 11%, included Burkitt's lymphoma (M-9687/3) 4.7%; Kaposi's sarcoma (M-9140/3) 3.7%; osteosarcoma (M-9180/3) 2.6% and malignant melanoma (M-8720/3) 1.9%. Fourty five percent of the patients admitted tobacco and alcohol consumption, of whom 95% were males. Oral malignant neoplasms were more common in males than females and occurred in a relatively young age group. Well-differentiated squamous cell carcinoma (M-8070/31) was the most common oral malignant neoplasm and was most frequently found on the mandibular gingivae (CO3.1), tongue (CO1.9-CO2.9) and floor of the mouth (CO4.9). The lip (COO-COO.9) was least affected with a high palatal (CO5.9) involvement.

The incidence of oropharyngeal cancer in Taiwan: an endemic betel quid chewing area

BACKGROUND

Oropharyngeal cancer is the one of the most common cancers in the world. The purpose of this study was to examine the trends in oropharyngeal cancer from 1979 to 1996 in Taiwan.

METHODS

Traditional cohort analysis was employed to show the birth-cohort effect of oropharyngeal cancer incidence. Age-period-cohort model analysis was used to examine the age, period and cohort effect between intraoral and pharyngeal cancer.

RESULT

A significant increasing trend in oropharyngeal cancer has been seen in males. The principal increases have been seen in tongue and mouth in males, and tongue in females. In males, an increasing trend was found in successive cohorts born after 1929. The increase in incidence of intraoral cancer of males was greater than the increase in incidence of pharyngeal cancer in the younger age group, more recent time periods and the younger cohorts.

CONCLUSION

The increasing incidence in oropharyngeal cancer in Taiwan is probably heavily influenced by the rising consumption of alcohol and use of betel quid. The effect of these etiologies on intraoral cancer was more significant in recent time periods, later cohorts and the younger group.

The epidemiology of mouth cancer: a review of global incidence

Mouth cancer (143-145 ICD-9) is a major health problem in many parts of the world. While its incidence is relatively low in most western countries there are some important exceptions to this trend: on the Indian subcontinent and in other parts of Asia it remains one of the most common forms of cancer. This review article summarises the global incidence of mouth cancer using cancer maps. Data have been compiled from the latest edition of Cancer Incidence in Five Continents and recent studies from various locations around the world. Significant geographic variation is noted in the incidence of mouth cancer, with high rates reported for the Indian subcontinent and parts of Asia (male incidence rates in excess of 10 per 100,000 per annum). It is also noted that as with other forms of oral cancer, the majority of population-based data for mouth cancer comes from the Western world with a paucity of reliable data from the so-called developing countries. Mouth cancer remains a serious health problem in many parts of the world with many regions reporting increasing incidence rates particularly in males. Ongoing research into the aetiologic risk factors associated with this disease must remain a very high priority if the causes of mouth cancer are to be established and disease control protocols introduced widely.

The epidemiology of tongue cancer: a review of global incidence

The tongue (141 ICD-9) is the most common intraoral site for cancer in most countries, however its global epidemiology shows significant geographic variation. This review paper summarises the global incidence of cancer of the tongue using cancer maps and references to recent studies from various locations. Tongue cancer remains a serious health problem in many countries including India (male incidence rates up to 6.5 per 100,000 per annum) and parts of Europe (male incidence rates in France up to 8.0 per 100,000 per annum). It is noted that as with other forms of oral cancer the majority of population-based data for tongue cancer comes from the Western world with a paucity of reliable data from the so-called developing countries. The tongue remains the most common intraoral site for oral cancer worldwide and in a number of countries it is a serious public health problem with significant morbidity and mortality. While the incidence of tongue cancer appears to be stable or falling in some regions of the world, in other areas it is rising, particularly among younger people.

The adverse health effects of tobacco and tobacco-related products

Tobacco use continues to occur in epidemic proportions and with it, significant morbidity and mortality. One third of smokers will die prematurely of a smoking-related disease. This article reviews the adverse health effects of tobacco use so that clinicians can be aware of the benefits patients will reap when they stop using this lethal substance.

Toombak use and cigarette smoking in the Sudan: estimates of prevalence in the Nile state

BACKGROUND

Survey data on the prevalence of use of oral snuff (toombak) and cigarette consumption according to various demographic factors are needed in the Sudan.

METHODS

A house to house cross-sectional survey of a random population sample of 4,535 households was performed. Of the 23,367 household members identified, 21,648 (92.6%) eligible individuals were questioned about tobacco use.

RESULTS

Among children and adolescents (4-17 years) prevalence of tobacco use was quite low (2%, range 1-2%), but there was an abrupt increase up to 25% in late adolescence. Among the adult population aged 18 years and older the prevalences of toombak use (34%) and cigarette smoking (12%) among males were significantly higher than among females (2.5 and 0.9%, respectively). The prevalence of toombak use among the male population aged 18 years and older was significantly higher in the rural than in the urban areas (35% vs 24%), while cigarette smoking had a higher prevalence in urban areas (18% vs 12%). The highest rates of toombak use were found in rural areas among the male population ages 30 years and older (mean 46.6%, range 45-47%).

CONCLUSIONS

In view of the high prevalence of tobacco use, especially of toombak, among the population surveyed, there is an urgent need to educate the public on the health consequences of these habits.

Epidemiology of cancer and other systemic effects associated with the use of smokeless tobacco

Persons who use chewing tobacco and snuff experience an increased risk of oral cancer. Because of the pharmacologic properties of nicotine and other constituents of smokeless tobacco, there is also concern that smokeless tobacco products may lead to cardiovascular diseases as well. The relatively few human population studies to date conflict with respect to whether smokeless tobacco use elevates cardiovascular risk factors or leads to cardiovascular disease or death from cardiovascular causes. Hemoglobin adducts to carcinogens present in smokeless tobacco products are measurable in the blood of smokeless tobacco users, indicating that smokeless-tobacco-related carcinogens circulate throughout the body. This prompts a concern that smokeless tobacco may increase risks of other cancers as well. The evidence to date from epidemiologic studies indicates no relationship between smokeless tobacco and bladder cancer, but there is suggestive evidence linking smokeless tobacco use to prostate cancer risk. Only single studies have been conducted of some cancers, and inconsistencies among studies of the same cancer site have been reported. Molecular epidemiologic studies may help identify markers of malignant transformation in smokeless tobacco users that may help in early intervention to prevent or ameliorate the consequences of oral cancer. Further studies are needed to determine more clearly the cardiovascular and non-oral cancer risks potentially associated with smokeless tobacco use.

Toombak-associated oral mucosal lesions in Sudanese show a low prevalence of epithelial dysplasia

Clinical (n = 281) and histopathological (n = 141) characteristics of toombak-associated oral mucosal lesions detected in an epidemiological study in northern Sudan in 1992/93 are described. The lesional site in the majority of toombak users was the anterior lower labial groove and the lower labial mucosa. 4 degrees (1-4) of clinical severity of lesions, similar to those used to characterise Swedish snuff-dipper's lesion, were applied. An association between the severity of mucosal lesions and a longer lifetime duration (> 10 years) of toombak use was found, but the severity was not related to the daily frequency of the habit. Parakeratosis, pale surface staining of the epithelium and basal cell hyperplasia were commonly observed, but epithelial dysplasia was infrequent (10/141). The most significant observation was a PAS-positive amorphous deposit between the lamina propria and the submucosa, found in 25/141 biopsies. The clinical and histopathological features of toombak lesions are closely similar to Swedish moist snuff-dipper's lesions and this may reflect the high alkalinity of these products, resulting in an alkaline burn on the oral mucosa following chronic exposure. The low prevalence of epithelial dysplasia implies a low risk of malignant transformation. Nevertheless, the high concentrations of tobacco-specific nitrosamines present in toombak, and the high prevalence of oral cancer in Sudan, mandate biopsy and careful histopathological analysis of any such lesions detected in habitues.

Toombak dipping and cancer of the oral cavity in the Sudan: a case-control study

To investigate the possible causal association between squamous-cell carcinomas of the oral cavity and use of toombak, we retrospectively compared the history of use of this substance in 375 patients with squamous-cell carcinomas of the lip, buccal cavity and floor of mouth, and 271 patients with squamous carcinomas of the tongue, palate and maxillary sinus, with 204 patients exhibiting non-squamous oral and non-oral malignant neoplasms and 2,820 individuals who had no malignancy, selected from the general population. The study revealed that the high prevalence of oral cancer in the Sudan is largely due to chronic use of toombak. The adjusted ORs associated with toombak dipping for the first case group, cancer of the lip, buccal cavity and floor of mouth in comparison with the hospital and population control groups, were 7.3 and 3.9 (95% confidence limits, 4.3-12.4 and 2.9-5.3) respectively and among long-term users the adjusted ORs were 11.0 and 4.3 (95% confidence limits, 4.8-25.1 and 2.9-6.3) respectively. The elevated risk found when investigating intra-oral cancers of sites in direct contact with toombak quid compared to those with little or no contact, confirms the hypothesis that direct contact with tissues is an important factor in tobacco carcinogenesis in the mouth. The increased risk associated with the use of toombak is of particular concern in view of its wide consumption in the Sudan.