Carcinogenicity of smokeless tobacco: Evidence from studies in humans & experimental animals

Effects of smokeless tobacco on cancer incidence and mortality: a global systematic review and meta-analysis

INTRODUCTION

The prevalence of smokeless tobacco consumption remains high despite policies on reduction interventions. This study aims to quantify the associations between smokeless tobacco use with cancer incidence and mortality globally.

METHODS

We conducted a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and PROSPERO protocol (ID: CRD42023390468). A comprehensive literature search was performed using PubMed, Web of Science, and Scopus databases, covering the period from January 1, 2000, to February 28, 2023. We included peer-reviewed observational studies, specifically case-control and cohort studies, where smokeless tobacco use was the primary exposure and cancer incidence, or mortality were the main outcomes. Three independent reviewers screened titles, abstracts, and full texts, and extracted data from the included studies. Risk of bias was assessed by the same three reviewers. Any disagreements were resolved through discussion with a fourth reviewer. We performed random-effects meta-analyses and assessed heterogeneity and publication bias to ensure the robustness of our findings.

RESULTS

Of the 3,611 articles identified, 80 were included in the final analysis. Increased risks were observed for cancer mortality [Risk Ratio (RR) 1.38, 95% Confidence Interval (CI) 1.22-1.56] and incidence [RR 1.17, 95% CI 1.08-1.27]. The specific cancer sites with increased mortality risk included head and neck cancers, as well as stomach cancer. For cancer incidence, associations were observed with head and neck, oral, esophageal, stomach, and pancreatic cancers. Significant heterogeneity (I2 statistic 65% to 90%) was observed among most cancer outcomes.

CONCLUSION

Our study found significant associations between smokeless tobacco use and cancer incidence and mortality. Targeted policy interventions, such as stricter regulations on smokeless tobacco use, are recommended to reduce its consumption and mitigate the associated cancer risks.

16S rDNA-Based Amplicon Analysis Unveiled a Correlation Between the Bacterial Diversity and Antibiotic Resistance Genes of Bacteriome of Commercial Smokeless Tobacco Products

The distribution of bacterial-derived antibiotic resistance genes (ARGs) in smokeless tobacco products is less explored and encourages understanding of the ARG profile of Indian smokeless tobacco products. Therefore, in the present investigation, ten commercial smokeless tobacco products were assessed for their bacterial diversity to understand the correlation between the inhabitant bacteria and predicted ARGs using a 16S rDNA-based metagenome analysis. Overall analysis showed the dominance of two phyla, i.e., Firmicutes (43.07%) and Proteobacteria (8.13%) among the samples, where Bacillus (9.76%), Terribacillus (8.06%), Lysinibacillus (5.8%), Alkalibacterium (5.6%), Oceanobacillus (3.52%), and Dickeya (3.1%) like genera were prevalent among these phyla. The phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt)-based analysis revealed 217 ARGs which were categorized into nine groups. Cationic antimicrobial polypeptides (CAMP, 33.8%), vancomycin (23.4%), penicillin-binding protein (13.8%), multidrug resistance MDR (10%), and β-lactam (9.3%) were among the top five contributors to ARGs. Staphylococcus, Dickeya, Bacillus, Aerococcus, and Alkalibacterium showed their strong and significant correlation (p value < 0.05) with various antibiotic resistance mechanisms. ARGs of different classes (blaTEM, blaSHV, blaCTX, tetX, vanA, aac3-II, mcr-1, intI-1, and intI2) were also successfully amplified in the metagenomes of SMT samples using their specific primers. The prevalence of ARGs in inhabitant bacteria of smokeless tobacco products suggests making steady policies to regulate the hygiene of commercial smokeless tobacco products.

Behavioural support and nicotine replacement therapy for smokeless tobacco cessation in Bangladesh, India and Pakistan: A pilot randomized controlled trial

BACKGROUND AND AIMS

Smokeless tobacco (ST) use in South Asia is high, yet interventions to support its cessation are lacking. We tested the feasibility of delivering interventions for ST cessation in South Asia.

DESIGN

We used a 2 × 2 factorial design, pilot randomized controlled trial with a duration of 26 weeks, including baseline and follow-up (6, 12 and 26 weeks) assessments.

SETTING

Two primary health-care facilities each in Dhaka (Bangladesh) and Karachi (Pakistan) and a walk-in cancer screening clinic in Noida (India) took part.

PARTICIPANTS

Adult daily ST users willing to make a quit attempt within 30 days. Of 392 screened, 264 participants [mean age: 35 years, standard deviation = 12.5, 140 (53%) male] were recruited between December 2020 and December 2021; 132 from Bangladesh, 44 from India and 88 from Pakistan.

INTERVENTIONS

Participants were randomized to one of three treatment options [8-week support through nicotine replacement therapy (NRT, n = 66), a behavioural intervention for smokeless tobacco cessation in adults (BISCA, n = 66) or their combination (n = 66)] or the control condition of very brief advice (VBA) to quit (n = 66).

MEASUREMENTS

Recruitment and retention, data completeness and feasibility of intervention delivery were evaluated. Biochemically verified abstinence from tobacco, using salivary cotinine, was measured at 26 weeks.

FINDINGS

Retention rates were 94.7% at 6 weeks, dropping to 89.4% at 26 weeks. Attendance in BISCA pre-quit (100%) and quit sessions (86.3%) was high, but lower in post-quit sessions (65.9%), with variability among countries. Adherence to NRT also varied (45.5% Bangladesh, 90% India). Data completion for key variables exceeded 93% among time-points, except at 26 weeks for questions on nicotine dependence (90%), urges (89%) and saliva samples (62.7%). Among follow-up time-points, self-reported abstinence was generally higher among participants receiving BISCA and/or NRT. At 26 weeks, biochemically verified abstinence was observed among 16 (12.1%) participants receiving BISCA and 13 (9.8%) participants receiving NRT.

CONCLUSIONS

This multi-country pilot randomized controlled trial of tobacco cessation among adult smokeless tobacco users in South Asia demonstrated the ability to recruit and retain participants and report abstinence, suggesting that a future definitive smokeless tobacco cessation trial is viable.

The association between anti-smoking legislation and prevalence of acute respiratory illnesses in Indian children

Objective

Exposure to tobacco smoke causes numerous health problems in children, and create burden on the population in terms of economy, morbidity and mortality. In order to protect the child from exposure to tobacco smoke in the outdoor environment, sufficient legislative enactments are available in Indian legislation. The objective of the present study is to investigate the fact that in absence of any specific laws stating about protection of children from exposure to tobacco smoke in indoor environment, whether outdoor related legislations are sufficient to protect children from exposureand to explore the scope for enforcement of both state and central laws in improving health of children in India.

Study design

The study considered cross-sectional survey data of Demographic and Health Survey Data on India, National Family and Health Survey fourth round (NFHS-4) for the year 2015-16 on Indian children (below age of four).

Methods

Both bivariate and multivariate logistic regression models were used to assess the impact of anti-smoking laws on the prevalence of acute respiratory infection (ARI) based on the place of residence, indoor tobacco smoke exposure and age of the child.

Results

The results have shown an inclination of ARI among children in association with states having single law, rural area resident, exposure to indoor tobacco smoke and age of the child, both as independent or in combination are quite conspicuous, and are found to be underestimated. The logistic regression also revealed the influence of these factors both as independent and even in interaction with other.

Conclusions

Legislative intervention through both at central (or national)and state levels through anti-smoking laws will decrease the indoor tobacco smoke exposure as a result ARI prevalence will also decrease among children in India.

Nicotine mediated epithelial modulations: An in-vitro evidence

Introduction

Nicotine, the main ingredient in tobacco, acts as a key alkaloid of nearly all tobacco products and has been demonstrated to facilitate tumorigenesis and accelerate metastasis. Further traditional tobacco products have shown to give systemic oral effects such as vasoconstriction, inflammation, and delayed wound healing, however; none of the reports have confirmed the significant knowledge of oral sequel of the effect of nicotine on oral epithelial cells. So, the current study aimed to investigate the effect of nicotine on epithelial transformation to a malignant state.

Material & methods

Through in-vitro experiments, the effects of nicotine on epithelial cells obtained from nicotine never exposed buccal mucosa were analyzed using total count and viability test, proliferation assay, cell cycle distribution assay, and PI3K/MAPK dual pathway activation assay.

Result & conclusion

MTT assay demonstrated that the proliferation of epithelial cells takes place at a 150 mM concentration of nicotine. Further, we identified the significantly increased cell count and viability in nicotine-exposed cells. Further, cell cycle distribution assay results demonstrated that nicotine forced the epithelial cells to enter the first growth phase. The same influence of nicotine was observed on the PI3K/MAPK dual pathway activation assay where a greater number of nicotine exposed cells showed dual pathway activation. In conclusion, the current study determined the potential mechanism of action of nicotine on oral epithelial cell proliferation through activating the oncogenic pathway. This may help to develop novel therapeutic strategies for the prevention of malignant transformation from smokeless tobacco-caused oral cancer.

Exploring the potential of dietary factors and plant extracts as chemopreventive agents in oral squamous cell carcinoma treatment

Oral cancer, particularly oral squamous cell carcinoma (OSCC), is a prevalent malignancy having a significant fatality rate worldwide. Despite advancements in conventional treatment modalities, the overall survival rate for OSCC remains low. Therefore, there is a critical need to explore alternative therapeutic approaches that can improve patient outcomes. This review focuses on the potential of dietary factors and plant extracts as chemopreventive agents in treating oral cancer. These compounds possess diverse biological functions encompassing a range of attributes, such as antioxidative, anti-inflammatory, and anticancer capabilities. By targeting multiple cellular pathways involved in carcinogenesis, they possess the capacity to hinder tumor growth and development, promote programmed cell death, and impede the progression of oral cancer. Signaling pathways targeted by natural compounds that have been included in this review include Akt/mTOR/NF-κB signaling, Hippo-Tafazzin signaling pathway, notch signaling pathway, mitochondrial pathway, and Sonic Hedgehog pathway.

Pan-American prevalence of smokeless tobacco use and association with oral potentially malignant disorders and head and neck cancer: a systematic review and meta-analysis

OBJECTIVES

To determine the prevalence of smokeless tobacco (SLT) use and its association with oral potentially malignant disorders (OPMDs) and head and neck cancer (HNC) in the Pan-American Health Organization (PAHO) region.

STUDY DESIGN

A literature search was conducted across 9 databases and other sources. The eligibility criteria were pediatric (0-18 years old) and adult (19 years and older) populations consuming any type of SLT. Meta-analysis was performed to determine the prevalence of SLT and the association between its use and OPMDs/HNC in the PAHO region; the Grading of Recommendations Assessment, Development, and Evaluation tool was used to verify the certainty of evidence.

RESULTS

Fifty-nine studies from 6 PAHO countries were included, of which 51 were also subjected to quantitative analysis. The pooled SLT prevalence of use was 15% (95%CI: 11.93-18.69) overall, 17% (95%CI: 13.25-22.65) in adults, and 11% (95%CI: 8.54-14.78) in the pediatric population. The highest reported SLT prevalence of use was 33.4% (95%CI: 27.17-39.93) in Venezuela. HNC was positively associated with SLT use (OR = 1.98, 95%CI: 1.54-2.55), with a moderate certainty of evidence. Among OPMDs, only leukoplakia reported a positive association with SLT use (OR = 8.38; 95%CI: 1.05-67.25). However, the quality of the evidence was very low.

CONCLUSION

A high consumption of SLT use, chewing tobacco and snuff, is reported among the adult population residing in the PAHO region with a positive association with the development of oral leukoplakia and HNC.

Advantages of the Combinatorial Molecular Targeted Therapy of Head and Neck Cancer-A Step before Anakoinosis-Based Personalized Treatment

The molecular initiators of Head and Heck Squamous Cell Carcinoma (HNSCC) are complex. Human Papillomavirus (HPV) infection is linked to an increasing number of HNSCC cases, but HPV-positive tumors generally have a good prognosis. External factors that promote the development of HPV-negative HNSCC include tobacco use, excessive alcohol consumption, and proinflammatory poor oral hygiene. On a molecular level, several events, including the well-known overexpression of epidermal growth factor receptors (EGFR) and related downstream signaling pathways, contribute to the development of HNSCC. Conventional chemotherapy is insufficient for many patients. Thus, molecular-based therapy for HNSCC offers patients a better chance at a cure. The first molecular target for therapy of HNSCC was EGFR, inhibited by monoclonal antibody cetuximab, but its use in monotherapy is insufficient and induces resistance. This article describes attempts at combinatorial molecular targeted therapy of HNSCC based on several molecular targets and exemplary drugs/drug candidates. The new concept of anakoinosis-based therapy, which means treatment that targets the intercellular and intracellular communication of cancer cells, is thought to be the way to improve the clinical outcome for HNSCC patients. The identification of a link between molecular targeted therapy and anakoinosis raises the potential for further progress in HPV-negative HNSCC therapy.

Genetic and epigenetic instability induced by betel quid associated chemicals

Over the years, betel quid chewing and tobacco use have attracted considerable interest as they are implicated as the most likely causative risk factors of oral and esophageal cancers. Although areca nut use and betel quid chewing may lead to apoptosis, chronic exposure to areca nut and slaked lime may promote pre-malignant and malignant transformation of oral cells. The putative mutagenic and carcinogenic mechanisms may involve endogenous nitrosation of areca and tobacco alkaloids as well as the presence of direct alkylating agents in betel quid and smokeless tobacco. Metabolic activation of carcinogenic N-nitrosamines by phase-I enzymes is required not only to elicit the genotoxicity via the reactive intermediates but also to potentiate the mutagenicity with the sporadic alkylations of nucleotide bases, resulting in the formation of diverse DNA adducts. Persistent DNA adducts provides the impetus for genetic and epigenetic lesions. The genetic and epigenetic factors cumulatively influence the development and progression of disorders such as cancer. Accumulation of numerous genetic and epigenetic aberrations due to long-term betel quid (with or without tobacco) chewing and tobacco use culminates into the development of head and neck cancers. We review recent evidence that supports putative mechanisms for mutagenicity and carcinogenicity of betel quid chewing along with tobacco (smoking and smokeless) use. The detailed molecular mechanisms of the extent of accumulation and patterns of genetic alterations, indicative of the prior exposure to carcinogens and alkylating agents because of BQ chewing and tobacco use, have not yet been elucidated.

Differential Regulation of Innate Lymphoid Cells in Human and Murine Oral Squamous Cell Carcinoma

Oral squamous cell carcinomas (OSCC) remain a major healthcare burden in Asian countries. In Pakistan alone, it is the most common cancer in males and second only to breast cancer in females. Alarmingly, treatment options for OSCC remain limited. With this context, investigations made to explore the inflammatory milieu of OSCC become highly relevant, with the hope of practicing immunotherapeutic approaches to address this highly prevalent tumor. We investigated the newly identified innate lymphoid cells (ILCs) and associated cytokines in well-defined human oral squamous cell carcinoma (OSCC) as well as in a 7,12-dimethylbenz[a]anthracene (DMBA)-induced murine model of OSCC using flow cytometry and quantitative real-time polymerase chain reaction (qPCR). We further went on to explore molecular circuitry involved in OSCC by developing a murine model of OSCC and using an α-Thy1 antibody to inhibit ILCs. Amongst the ILCs that we found in human OSCC, ILC3 (23%) was the most abundant, followed by ILC2 (17%) and ILC1 (1%). Mice were divided into four groups: DMBA (n = 33), DMBA+antibody (Ab) (n = 30), acetone (n = 5), and control (n = 5). In murine OSCC tissues, ILC1 and ILC3 were down-infiltrated, while ILC2 remained unchanged compared to controls. Interestingly, compared to the controls (DMBA group), mice treated with the α-Thy1 antibody showed fewer numbers of large tumors, and a larger percentage of these mice were tumor-free at this study's end point. We present novel data on the differential expansion/downsizing of ILCs in OSCC, which provides a pivotal basis to dive deeper into molecular circuitry and the OSCC tumor niche to devise novel diagnostic, therapeutic, and prognostic strategies to prevent/treat oral cancers.

Does Maras powder affect the nasal mucociliary clearence?

PURPOSE

Many studies have been conducted about the effect of cigarettes and other tobacco products on mucociliary clearance. However, there has been no study of the relationship between mucociliary clearance and Maras powder, which is a smokeless tobacco product. The aim of this study was to evaluate the effect of Maras powder use on mucociliary clearance through comparisons with cigarette smokers and those who used no tobacco products.

METHODS

The study included 75 male volunteers, aged 23-54 years. Group 1 (n: 25) comprised subjects who do not use any tobacco products, Group 2 (n: 25) those who smoked cigarettes, and Group 3 (n: 25) those who used Maraş powder. The saccharin test was used to evaluate mucociliary clearance and the time was recorded in seconds. The groups were statistically compared in respect of mean age and mucociliary clearance time (MCCT).

RESULTS

The mean MCCT was determined to be 645.8 ± 200 secs for the whole study sample, 497 ± 108 secs for Group 1, 796 ± 200 secs for Group 2, and 644 ± 161 secs for Group 3. The difference between the groups in respect of MCCT was statistically significant (p < 0.001). No statistically significant difference was determined between the groups in respect of mean age (p = 0.730).

CONCLUSION

The study results demonstrated that the nasal mucociliary clearance time was prolonged both by cigarettes and by the use of Maras powder, and that this time was prolonged more by cigarette smoking than the use of Maras powder.

Behavioural support and nicotine replacement therapy for smokeless tobacco cessation: protocol for a pilot randomised-controlled multi-country trial

BACKGROUND

Smokeless tobacco (ST) is consumed globally by more than 350 million people, with approximately 85% of all users based in South and Southeast Asia. In this region, ST products are cheap and easily accessible. Evidence-based interventions to people quit ST use are lacking. This study aims to test the feasibility of conducting a future definitive trial of ST cessation, using a culturally adapted behavioural intervention, and/or nicotine replacement therapy (NRT) in three South Asian countries.

METHODS

We will conduct a factorial design, randomised-controlled pilot trial in Bangladesh, India and Pakistan. Daily ST users will be recruited from primary health care settings in Dhaka, Noida and Karachi. Participants will be individually randomised to receive intervention A (4 or 6 mg NRT chewing gum for 8-weeks), intervention B (BISCA: face-to-face behavioural support for ST cessation), a combination of interventions A and B or usual care (Very Brief Advice - VBA). The participants will provide demographic and ST use related data at baseline, and at 6, 12 and 26 weeks of follow-up. Salivary cotinine samples will be collected at baseline and 26 weeks. The analyses will undertake an assessment of the feasibility of recruitment, randomisation, data collection and participant retention, as well as the feasibility of intervention delivery. We will also identify potential cessation outcomes to inform the main trial, understand the implementation, context and mechanisms of impact through a process evaluation and, thirdly, establish health resource use and impact on the quality of life through health economic data.

DISCUSSION

The widespread and continued use of ST products in South Asia is consistent with a high rate of associated diseases and negative impact on the quality of life. The identification of feasible, effective and cost-effective interventions for ST is necessary to inform national and regional efforts to reduce ST use at the population level. The findings of this pilot trial will inform the development of larger trials for ST cessation among South Asian users, with relevance to wider regions and populations having high rates of ST use.

TRIAL REGISTRATION

ISRCTN identifier 65109397.

The relationship between P16INK4A and TP53 promoter methylation and the risk and prognosis in patients with oesophageal cancer in Thailand

DNA methylation can regulate the expression of tumour suppressor genes P16 and TP53, environmental factors, which are both important factors related to an increased risk and prognosis of oesophageal cancer (EC). However, the association between these two genes methylation status, as well as the effects of gene-environment interactions, EC risk remains unclear. A Hospital-based case-control study data were collected from 105 new EC cases and 108 controls. Promoter methylation status was investigated for P16 and TP53 genes using methylation-specific polymerase (MSP) chain reaction methods with SYBR green. Logistic and Cox regression models were used to analyse the association of P16 and TP53 promotor methylation status with EC risk and prognosis, respectively. Our results suggest P16, TP53 methylation significantly increased the risk of EC (OR = 5.24, 95% CI: 2.57-10.66, P < 0.001; OR = 3.38, 95% CI: 1.17-6.67, P < 0.001, respectively). In addition, P16 and TP53 promoter methylation status and the combined effects between environmental factors and its methylations in tissue were correlated with the EC risk and prognosis of EC patients. As a new biomarker, the methylation of P16 and TP53 can serve as a potential predictive biomarker of EC.

Smokeless tobacco and cigarette smoking: chemical mechanisms and cancer prevention

Tobacco products present a deadly combination of nicotine addiction and carcinogen exposure resulting in millions of cancer deaths per year worldwide. A plethora of smokeless tobacco products lead to unacceptable exposure to multiple carcinogens, including the tobacco-specific nitrosamine N'-nitrosonornicotine, a likely cause of the commonly occurring oral cavity cancers observed particularly in South-East Asian countries. Cigarettes continue to deliver a large number of carcinogens, including tobacco-specific nitrosamines, polycyclic aromatic hydrocarbons and volatile organic compounds. The multiple carcinogens in cigarette smoke are responsible for the complex mutations observed in critical cancer genes. The exposure of smokeless tobacco users and smokers to carcinogens and toxicants can now be monitored by urinary and DNA adduct biomarkers that may be able to identify those individuals at highest risk of cancer so that effective cancer prevention interventions can be initiated. Regulation of the levels of carcinogens, toxicants and nicotine in tobacco products and evidence-based tobacco control efforts are now recognized as established pathways to preventing tobacco related cancer.

Oral lesions associated with smokeless tobacco users in Saudi Arabia: Single center cross-sectional study

Introduction

Smokeless tobacco (SLT) causes significant harm to the oral cavity and is considered a risk factor for oral cancer. Various forms, products, and patterns of SLT are used across different populations. Many products, such as nicotine and betel nut, have addictive and carcinogenic properties. SLT use is associated with benign, premalignant, or malignant lesions. This study aimed to identify the characteristics of these oral lesions and their association with SLT exposure.

Materials and methods

This cross-sectional study, performed at our institution’s Faculty of Dentistry, included all the patients with a history of using SLT within a 5-year period at the oral medicine clinic. The patients’ demographic details were collected, and information regarding habit, duration, frequency, site of placement, and history of habit discontinuity were recorded. If a biopsy was performed, the diagnoses were also reported.

Results

Of the 59 patients included, 89.8% were male and 10.2% were female. SLT lesions in the oral cavity were usually focal lesions (76.3%). The most preferred placement site by SLT users was the mandibular posterior vestibule. Follow-up of SLT patients after quitting or clinical changes in the placement site showed a 92.8% regression or complete healing of the lesions. Of the 59 patients who underwent SLT, 18.6% were diagnosed with oral squamous cell carcinoma.

Conclusion

This study demonstrated a high percentage of remarkable regression or complete healing of SLT lesions related to early diagnosis and habit change. In contrast, 18.6% of the lesions progressed to SCC.

Cost-effectiveness of oral cancer screening approaches by visual examination: Systematic review

The present study is the first systematic review of papers that have performed a full economic evaluation on oral cancer screening strategies using visual oral examination. The review questions were (1) Is screening a cost-effective strategy in oral cancer? (2) What is the most cost-effective strategy among the different screening approaches in oral cancer? The main outcome measure was the incremental cost-effectiveness ratio. The study identifies and reviews seven full economic evaluations. The included studies scored 75%-100% on the methodological appraisal. Majority of the studies reports that oral cancer screening is a cost-effective strategy, especially in an opportunistic setting and high-risk subset of patients. The results were sensitive to cost and effectiveness parameters. Oral cancer screening, though found cost-effective, the uncertainty around these parameters necessitates additional studies that include better estimates in the modeling assessments. The heterogeneity in studies limited comparison and generalization.

Comparative Evaluation of Salivary Sialic Acid Levels Among Beedi Rollers and Tobacco Users in Mangalore, South India

Introduction: According to World Health Organization, the global cancer burden is estimated to have risen to 18.1 million new cases and 9.6 million deaths in 2018. Tobacco use is a leading cause of cancer and of death from cancer. Beedis are the most popular smoking form of tobacco in India. Thirty-four percent of the tobacco produced in India is used for making beedis. The beedi sector is agroforestry-based and the second largest industry in India with approximately 4.4 million full-time beedi workers in India. Toxic constituents present in tobacco are released into the ambient air during the processing of beedis.

Methods: A descriptive cross-sectional study was conducted to assess and compare salivary sialic acid levels among beedi rollers, tobacco smokers, smokeless tobacco users and individuals with no tobacco exposure. The study sample comprised of 140 individuals who were 30 to 60 years old, who attended dental screening and treatment camps in rural and urban areas in Mangalore, conducted by the Department of Public Health Dentistry, Yenepoya Dental College and patients who visited the Department of Oral Medicine and Radiology of Yenepoya Dental College. Saliva was collected by passive drool method into a sterile container. Biochemical analysis of salivary sialic acid was done using the acidic ninhydrin method. Continuous variables are expressed in terms of mean and standard deviation. Categorical variables are expressed in terms of frequencies and percentages. To compare salivary sialic acid levels between the groups ANOVA was used. The Chi-square test was used to compare categorical variables between the groups.

Results: A total of 140 participants, 35 beedi rollers, 35 smokers, 35 smokeless tobacco users and 35 individuals with no tobacco exposure participated in the study. Among the 140 participants, 90 participants were males and 50 participants were females. There was a statistically significant difference in the mean salivary sialic acid level between the different groups (p<0.001) with smokeless tobacco users having the highest (10.60 mg/dL) mean salivary sialic acid level. It was found that the mean salivary sialic acid level reduced as the age progressed, even though there was no statistically significant difference. There was a statistically significant difference in the mean salivary sialic acid level between the different groups (p=0.010) with participants with 11 to 20 years of exposure to tobacco having the highest (8.67 mg/dL) mean salivary sialic acid level and participants with no tobacco exposure having least (3.06 mg/dL) mean salivary sialic acid level.

Conclusion: The salivary sialic acid level was more in beedi rollers than individuals with no tobacco exposure, even though the difference was not statistically significant. The results showed elevated levels of salivary sialic acid in smokeless tobacco users followed by tobacco smokers. This may be an indication that smokeless tobacco use has harmful effects similar to or more than tobacco smoking since salivary sialic acid levels in smokeless tobacco users were higher than those in smokers.

Novel Pathways and Mechanism of Nicotine-Induced Oral Carcinogenesis

BACKGROUND

Smokeless Tobacco (SLT) contains 9 times more nicotine than Smoked Tobacco (SMT). The carcinogenic effect of nicotine is intensified by converting nicotine-to-nicotine-derived Nitrosamines (NDNs).

METHODS

A review of the literature was conducted with a tailored search strategy to unravel the novel pathways and mechanisms of nicotine-induced oral carcinogenesis.

RESULTS

Nicotine and NDNs act on nicotinic Acetylcholine Receptors (nAChRs) as agonists. Nicotine facilitates cravings through α4β2nAChR and α7nAChR, via enhanced brain dopamine release. Nicotine binding to nAChR promotes proliferation, migration, invasion, chemoresistance, radioresistance, and metastasis of oral cancer cells. Nicotine binding to α7nAChR on keratinocytes triggers Ras/Raf-1/MEK1/ERK cascade promoting anti-apoptosis and pro-proliferative effects. Furthermore, the nicotine-enhanced metastasis is subdued on nAChR blockade through reduced nuclear localization of p-EGFR.

CONCLUSION

Protracted exposure to nicotine/NDN augments cancer-stimulatory α7nAChR and desensitizes cancer inhibitory α4β2nAChR. Since nAChRs dictate both addictive and carcinogenic effects of nicotine, it seems counterintuitive to designate nicotine just as an addictive agent devoid of any carcinogenicity.

The ultra-structural, metabolomic and metagenomic characterisation of the sudanese smokeless tobacco 'Toombak'

Toombak is a smokeless tobacco produced from the Nicotiana rustica tobacco plant from Sudan. Pre-prepared and ready to buy Toombak samples were analysed using mass spectrometry (heavy metals), gas and liquid chromatography (metabolomics), 16S rRNA metagenomic sequencing (microbiome) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and pH analysis. Chromium, cobalt, and copper were high in the pre-prepared form of Toombak while iron, tobacco specific nitrosamines (TSNAs), formaldehyde and acetaldehyde were high in both types. Firmicutes and Actinobacteria dominated Toombak. Samples of ready to buy Toombak showed inter-variational differences depending on place of purchase. We found Virgibacillus were increased in the pre-prepared form while Corynebacterium casei, Atopococus tabaci, Atopostipes suicloacalis, Oceanobacillus chironomi and Staphylococcus gallinarum were the most abundant species in the ready to buy forms. PICRUSt analysis highlighted increased activity of metal transport systems in the ready to buy samples as well as an antibiotic transport system. SEM-EDX highlighted large non-homogenous, irregular particles with increased sodium, while pH of samples was in the alkaline range. The final composition of Toombak is affected by its method of preparation and the end product has the potential to impart many negative consequences on the health of its users. TSNA levels observed in Toombak were some of the highest in the world while the micro-environment of Toombak supports a distinct microbiota profile.

Structural changes, increased hypoxia, and oxidative DNA damage in placenta due to maternal smokeless tobacco use

BACKGROUND

Smokeless tobacco (SLT) consumption during pregnancy is a well-recognized health risk that causes placental damage including hypoxia and oxidative damage. Although consumption of SLT by women varies from region to region, majority of tea leave pluckers consume SLT for relieving stress and pain. Still, the effects of SLT consumption have not been evaluated in tea garden workers (TGW). While previous studies have attempted to report effects of cigarette smoke using in vitro model, hypoxia-inducible factor (HIF)-1α expression in human placentae from pregnant women exposed to SLT has not been previously studied. This study was aimed to explore the effects of SLT consumption on placental structure, expression of HIF-1α and oxidative DNA damage in sample population of TGW.

METHODS

A total of 51 placentae were collected from SLT users and nonusers (n = 30 and 21, respectively) with full-term normal delivery, who were involved in the plucking of tea leaves during pregnancy in tea plantation. Low birth weight (LBW, i.e., weight <2,500 g) and normal birth weight (NBW) groups among both SLT user and nonuser were compared for the stated parameters. Placental tissues were processed for transmission electron microscopy (TEM) study and immunohistochemical analysis for the expression of HIF-1α and 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

Altered ultrastructural characteristics were observed in the tertiary villi of LBW group among SLT users which included endothelial cells protrusion into capillary lumen, degenerated nuclei, significant thickening of trophoblast basement membrane and vasculo-syncytial membrane, abnormalities of the microvilli, swollen or damaged mitochondria, and dilatation in endoplasmic reticulum cisternae. Furthermore, significant reduction in the perimeter, area, and number of the stromal capillary of the tertiary villi of placenta were found in LBW group as compared with NBW group from the SLT users. Enhanced expression for HIF-1α and oxidative DNA damage (8-OHdG) biomarker was observed in SLT users as compared with nonusers.

CONCLUSIONS

Maternal SLT exposure during pregnancy may be associated with villus hypoxia and consequently oxidative DNA damage. It is presumed that deleterious effect of SLT exposure on placenta could result in impairment of placental barrier, and restrict nutrient and oxygen supply from mother to fetus, and thus could be a cause of fetal growth restriction.

Evidence of Association of CYP1A1 Expression in Blood Lymphocytes and Clinicopathological Variables in Oral Cancer

Association of smokeless tobacco (SLT) with oral cancer is well documented. The nitrosamines of SLT are metabolically bioactivated by CYP1A1. Therefore, in this pilot study, we investigated association of CYP1A1 expression with polymorphism, clinicopathological variables and outcome in exclusive SLT chewers. Semiquantitative RT-PCR analysis on RNA isolated from peripheral blood lymphocytes of 65 histopathologically confirmed cases revealed increased CYP1A1 mRNA expression in Msp I (CYP1A1*2A) and Ile/Val (CYP1A1*2C) polymorphic variants. A higher trend of CYP1A1 mRNA levels in invasive and recurrent tumors which also associated with shorter disease free and overall survival was seen. Odds ratio analysis indicated the association of higher CYP1A1 mRNA levels with disease aggressiveness i.e. metastasis and invasion. Study revealed wider oncogenic role of CYP1A1 in oral cancer patients and justifies further studies and analysis in a large cohort.

Looking beyond the smokescreen: can the oral microbiome be a tool or target in the management of tobacco-associated oral cancer?

A wide range of microbes inhabit the oral cavity, and bacterial and fungal communities most often exist as structured communities or biofilms. The use of tobacco alters the structure of the oral microbiome, including that of potentially malignant lesions, and the altered oral microbiome influences key microenvironmental changes such as chronic inflammation, secretion of carcinogenic toxins, cellular and tissue remodelling and suppression of apoptosis. Given this, it is clear that the bacterial and fungal biofilms in potentially malignant states are likely not passive entities, but could play a critical role in shaping potential malignant and carcinogenic conditions. This holds potential towards leveraging the oral microbiome for the management of tobacco-associated potentially malignant lesions and oral cancer. Here, we explore this line of investigation by reviewing the effects of tobacco in shaping the oral microbiome, and analyse the available evidence in the light of the microbiome of oral potentially malignant and cancerous lesions, and the role of dysbiosis in carcinogenesis. Finally, we discuss possible interventions and approaches using which the oral microbiome could be leveraged towards precision-based oral cancer therapeutics.

A review of tobacco abuse and its epidemiological consequences

Aim

The economic burden caused by death and disease in the world is credited mainly to tobacco use—currently linked to approximately 8,000,000 deaths per year with approximately 80% of these faralities reported in low and middle income economies. The World Health Organization (WHO) estimates that nearly 7,000,000 deaths are attributed to direct tobacco use, while approximately 1,200,000 non-smokers exposed to second hand cigarette smoke die every year. Accordingly, tobacco use is a major threat to the public health infrastructure; therefore, proper cessation interventions must be put in place to curb tobacco abuse and ease economic and social burdens caused by the tobacco epidemic.

Methods

A systematic review was conducted to investigate how scientific efforts have been advanced towards harm reduction among smokers and non-smokers. Relevant articles published during the period 2010–2020 in PubMed, Crossref, Google scholar, and Web of Science were used in this study. The articles were selected based on health impacts of cigarette smoking, tobacco cessation and emerging diseases, including Covid−19. Various cessation strategies have been identified although their efficiency is yet to match the desired results.

Results

A series of carcinogenic chemicals are generated during cigarette smoking resulting in serious health complications such as cancer and mutagenesis. The precursors for tobacco induced diseases are toxic and carcinogenic chemicals of the nitrosamine type, aldehydes, polonium-210 and benzo[a]pyrene, which bio-accumulate in the body system during cigarette smoking to cause disease. Rehabilitation facilities, use of drugs to diminish the desire to smoke, heavy taxation of tobacco products and warning labels on cigarettes are some of the cessation strategies employed towards curbing tobacco abuse.

Conclusion

The need for further research to develop better methods and research based policies for safe cigarette smoking and workable cessation strategies must be a priority in order to deal with the tobacco epidemic. Campaigns to promote tobacco cessation and abstinence are recommended in this review as a sure measure to mitigate against the deleterious impacts caused by cigarette smoking and tobacco abuse.

Betel Quid Addiction: A Review of Its Addiction Mechanisms and Pharmacological Management as an Emerging Modality for Habit Cessation

Areca-nut (AN) and added smokeless-tobacco (SLT) are considered agents that may cause addiction to betel-quid (BQ). However, the primary addictive substance in AN is not clearly understood. Objective: The present review evaluates possible addictive chemicals in AN with their mechanisms of action for progression to BQ dependence, as it is essential to overcome barriers in BQ cessation. It also identifies innovative treatment modalities in BQ cessation including the scope for research on pharmacotherapy using Monoamine-oxidase Inhibitors, Selective Serotonin Re-uptake Inhibitors and Norepinephrine Dopamine Reuptake Inhibitors. Methods: This is a narrative review on addictive properties of BQ and trials undertaken to promote cessation of SLT or AN use. Results: Twenty interventional studies, three by behavioral therapy and seventeen using pharmacotherapy were reviewed. There was heterogeneity in reported follow up times, most studies reporting data at 12 weeks with abstinence rates of 45-55% for SLT cessation and at 8 weeks with abstinence rates around 35% for AN cessation. Conclusion: Even though literature reveals a few cessation programs through behavioral support for BQ addiction, its success has been limited in certain instances mainly due to addictive properties of AN, resulting in withdrawal and relapse. Hence, in line with pharmacotherapy in tobacco smoking cessation, potential pharmacological agents to assist in cessation of SLT and AN require more attention. Several clinical trials for SLT cessation have been carried out with varying levels of success using Nicotine Replacement Therapy and Varenicline while trials on antidepressants for SLT and AN cessation are also emerging.

Head and neck squamous cell carcinoma

Most head and neck cancers are derived from the mucosal epithelium in the oral cavity, pharynx and larynx and are known collectively as head and neck squamous cell carcinoma (HNSCC). Oral cavity and larynx cancers are generally associated with tobacco consumption, alcohol abuse or both, whereas pharynx cancers are increasingly attributed to infection with human papillomavirus (HPV), primarily HPV-16. Thus, HNSCC can be separated into HPV-negative and HPV-positive HNSCC. Despite evidence of histological progression from cellular atypia through various degrees of dysplasia, ultimately leading to invasive HNSCC, most patients are diagnosed with late-stage HNSCC without a clinically evident antecedent pre-malignant lesion. Traditional staging of HNSCC using the tumour-node-metastasis system has been supplemented by the 2017 AJCC/UICC staging system, which incorporates additional information relevant to HPV-positive disease. Treatment is generally multimodal, consisting of surgery followed by chemoradiotherapy (CRT) for oral cavity cancers and primary CRT for pharynx and larynx cancers. The EGFR monoclonal antibody cetuximab is generally used in combination with radiation in HPV-negative HNSCC where comorbidities prevent the use of cytotoxic chemotherapy. The FDA approved the immune checkpoint inhibitors pembrolizumab and nivolumab for treatment of recurrent or metastatic HNSCC and pembrolizumab as primary treatment for unresectable disease. Elucidation of the molecular genetic landscape of HNSCC over the past decade has revealed new opportunities for therapeutic intervention. Ongoing efforts aim to integrate our understanding of HNSCC biology and immunobiology to identify predictive biomarkers that will enable delivery of the most effective, least-toxic therapies.

Anaerobic bacterial communities associated with oral carcinoma: Intratumoral, surface-biofilm and salivary microbiota

It was estimated that more than 700 bacterial species inhabit the oral cavity of healthy humans. Anaerobes comprise a significant fraction of the oral bacteriome and play an important role in the formation of multi-species biofilms attached to various anatomical sites. Bacterial biofilms are also associated with pathologic laesions of the oral cavity, including oral squamous cell carcinoma (OSCC), and distinct oral taxa could also be detected within the tumors, i.e. in deep biopsy samples. These observations suggested that certain oral bacteria or oral bacterial communities may play a causative role in oral carcinogenesis, in addition to the well characterized risk factors of oral cancer. Alternatively, it was also proposed that a subset of oral bacteria may have a growth advantage in the unique microenvironment of OSCC. Recently, a series of studies analysed the OSCC-associated bacterial communities using metataxonomic, metagenomic and metatranscriptomic approaches. This review outlines the major differences between the community structure of microbiota in tumor biopsy, surface-biofilm and salivary or oral wash samples collected from OSCC patients, compared to corresponding samples from control persons. A special emphasis is given to the anaerobic bacteria Fusobacterium nucleatum and Fusobacterium periodonticum that were characterised repeatedly as "OSCC-associated" in independent studies. Predicted microbial functions and relevant in vivo experimental models of oral carcinogenesis will also be summarized.

The Potential of Phytochemicals in Oral Cancer Prevention and Therapy: A Review of the Evidence

The etiological factors of oral cancer are complex including drinking alcohol, smoking tobacco, betel quid chewing, human papillomavirus infection, and nutritional deficiencies. Understanding the molecular mechanism of oral cancer is vital. The traditional treatment for patients with oral squamous cell carcinoma (e.g., surgery, radiotherapy, and chemotherapy) and targeted molecular therapy still have numerous shortcomings. In recent years, the use of phytochemical factors to prevent or treat cancer has received increasing attention. These phytochemicals have little or no toxicity against healthy tissues and are thus ideal chemopreventive agents. However, phytochemicals usually have low water solubility, low bioavailability, and insufficient targeting which limit therapeutic use. Numerous studies have investigated the development of phytochemical delivery systems to address these problems. The present article provides an overview of oral cancer including the etiological factors, diagnosis, and traditional therapy. Furthermore, the classification, dietary sources, anticancer bioactivity, delivery system improvements, and molecular mechanisms against oral cancer of phytochemicals are also discussed in this review.

Screening for oral cancer: Future prospects, research and policy development for Asia

Although the incidence of oral cavity cancer is high among low and middle income countries in Asia where the risk habits (tobacco smoking, tobacco chewing and betel quid use) are common, the benefits for introducing oral cancer screening for the whole population in these countries still remains controversial. It is disappointing, but not surprising that many of studies, without control arms, could not provide a clear answer as to whether screening is effective in reducing mortality or combating rising incidence trends. Only one Indian study that reported a randomized controlled trial (RCT) elucidated that mass screening for high risk groups could significantly reduce the cancer mortality or down-stage cancers detected by screening. Several professional organizations that considered any potential benefits of oral cancer screening remain unconvinced that the current knowledge on its natural history, available tests and interventions to treat potentially malignant disorders satisfy the desirable criteria to recommend organized screening for oral cancer. In this review we discuss advantages and disadvantages for oral cancer screening particularly with reference to high incidence countries in Asia. If screening is undertaken, we propose that it is targeted to high risk groups and to combine screening with education on risky life-styles so that overall incidence can be reduced in the future. Further research on increasing public awarenes and impact of professional education such as e-learning to reduce diagnostic delays, studies on the natural history of oral potentially malignant disorders and cancer, comprehensive tobacco and areca nut cessation programs, developing tools to identify high-risk individuals and high-risk lesions are proposed.

Quantification of Nicotine and Cotinine in Plasma, Saliva, and Urine by HPLC Method in Chewing Tobacco Users

BACKGROUND

Nicotine acts as major alkaloid of all tobacco products including smokeless tobacco (SLT) forms. The mode of SLT consumption is in the form of chewing under the cheek or lip and induced biochemical alterations in the plasma, saliva, and urine.

MATERIALS AND METHODS

The smokeless tobacco products like Raja or blue bull tobacco brands are widely consumed by human male volunteers under the age of 18-30 years for the period of 3 years consisting of 30g per day. The concentrations of nicotine and cotinine in samples of plasma, saliva, and urine are quantified by the method of HPLC. The remaining variables of plasma are evaluated by auto analyzer and spectrophotometric methods.

RESULTS

The analysis of results presented that significant increase in the levels of nicotine and cotinine in plasma, saliva, and urine of chewing tobacco users. The lipid profile (Cholesterol, triglycerides, HDL-C, and LDL-C), liver marker enzymes (SGOT, SGPT, and ALP), kidney markers (Creatinine, urea, and uric acid), glucose, and the remaining variables are present within normal range observed in SLT users. The lipid peroxidation (LPO), nitric oxide (NO) (NO2 and NO3), protein carbonyls (PCO), and peroxynitrites (ONOO-) are reported to be higher levels in the plasma of experimental subjects in comparison with normal controls. The various brands of tobacco varieties (Raja, madhu chhap, hans chhap, miraj, badshah, blue bull, and swagat gold tobacco) are presented.

CONCLUSION

The chewing tobacco users exhibited greater amounts of nicotine and cotinine are at risk of cardiovascular due to nicotine has cardiovascular effects, and oral cancer disease complications in the future for chronic consumption of smokeless tobacco products  due to the presence of carcinogens of tobacco-specific N-nitrosamines.