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.

Uniqueness of lung cancer in Southeast Asia

Lung cancer varies between Caucasians and Asians. There have been differences recorded in the epidemiology, genomics, standard therapies and outcomes, with variations according to the geography and ethnicity which affect the decision for optimal treatment of the patients. To better understand the profile of lung cancer in Southeast Asia, with a focus on India, we have comprehensively reviewed the available data, and discuss the challenges and the way forward. A substantial proportion of patients with lung cancer in Southeast Asia are neversmokers, and adenocarcinoma is the common histopathologic subtype, found in approximately a third of the patients. EGFR mutations are noted in 23-30% of patients, and ALK rearrangements are noted in 5-7%. Therapies are similar to global standards, although access to newer modalities and molecules is a challenge. Collaborative research, political will with various policy changes and patient advocacy are urgently needed.

Contribution of Endothelial Dysfunction to Cancer Susceptibility and Progression: A Comprehensive Narrative Review on the Genetic Risk Component

Venous thromboembolism (VTE) is a challenging clinical obstacle in oncological settings, marked by elevated incidence rates and resulting morbidity and mortality. In the context of cancer-associated thrombosis (CAT), endothelial dysfunction (ED) plays a crucial role in promoting a pro-thrombotic environment as endothelial cells lose their ability to regulate blood flow and coagulation. Moreover, emerging research suggests that this disorder may not only contribute to CAT but also impact tumorigenesis itself. Indeed, a dysfunctional endothelium may promote resistance to therapy and favour tumour progression and dissemination. While extensive research has elucidated the multifaceted mechanisms of ED pathogenesis, the genetic component remains a focal point of investigation. This comprehensive narrative review thus delves into the genetic landscape of ED and its potential ramifications on cancer progression. A thorough examination of genetic variants, specifically polymorphisms, within key genes involved in ED pathogenesis, namely eNOS, EDN1, ACE, AGT, F2, SELP, SELE, VWF, ICAM1, and VCAM1, was conducted. Overall, these polymorphisms seem to play a context-dependent role, exerting both oncogenic and tumour suppressor effects depending on the tumour and other environmental factors. In-depth studies are needed to uncover the mechanisms connecting these DNA variations to the pathogenesis of malignant diseases.

Genetic variants in the renin-angiotensin-aldosterone system: Impact on cancer risk, prognosis, and therapeutic directions

Although renin-angiotensin-aldosterone system (RAAS) is known to maintain blood pressure and electrolyte balance, it has recently been linked to a number of biological processes such as angiogenesis, tumorigenesis, metastasis, and cellular proliferation, increasing the risk of cancer development and progression. Multiple genetic variants have been found to affect the genes encoding RAAS components, altering gene transcription and protein expression. This review provides an up-to-date insight into the role of RAAS in carcinogenesis, as well as the impact of RAAS genetic variants on the risk of cancer development, progression, and patient survival and outcomes, as well as response to treatment. This paves the way for the application of precision medicine in cancer risk assessment and management by implementing preventative programs in individuals at risk and guiding the therapeutic direction in cancer patients.

Associations between I/D polymorphism in the ACE gene and lung cancer: an updated systematic review and a meta-analysis

Background

We evaluated the association between the I/D polymorphism in the ACE gene and lung cancer risk by performing a meta-analysis.

Methods

The heterogeneity in the study was tested using the Cochran χ²-based Q statistic test and I² test, and then the random ratio or fixed effect was utilized to merge the odds ratios (ORs) and 95% confidence intervals (CIs) to estimate the strength of the association between ACE polymorphisms and susceptibility to lung cancer. Sensitivity analysis was also performed. Using funnel plot and Begg’s rank test, we investigated the publication bias. All statistical analyses were performed using Stata 12.0 and RevMan 5.3.

Results

A total of 4307 participants (2181 patients; 2126 controls) were included in the 12 case–control studies. No significant association was found between the ACE I/D polymorphism and lung cancer risk (II vs. ID + DD: OR = 1.22, 95% CI = 0.89–1.68; II + ID vs. DD: OR = 1.21, 95% CI = 0.90–1.63; I vs. D: OR = 1.15, 95% CI = 0.95–1.39). In the subgroup analysis by ethnicity, no significant association between the ACE I/D polymorphism and lung cancer risk was found among Asian and Caucasian populations for the comparisons of II vs. ID + DD, II + ID vs. DD, and I vs. D genetic models.

Conclusion

The ACE I/D polymorphism is not associated with the risk of lung cancer.

Cost-effectiveness of lung cancer screening and treatment methods: a systematic review of systematic reviews

BACKGROUND

Due to extensive literature in the field of lung cancer and their heterogeneous results, the aim of this study was to systematically review of systematic reviews studies which reviewed the cost-effectiveness of various lung cancer screening and treatment methods.

METHODS

In this systematic review of systematic reviews study, required data were collected searching the following key words which selected from Mesh: "lung cancer", "lung oncology", "lung Carcinoma", "lung neoplasm", "lung tumors", "cost- effectiveness", "systematic review" and "Meta-analysis". The following databases were searched: PubMed, Cochrane Library electronic databases, Google Scholar, and Scopus. Two reviewers (RA and A-AS) evaluated the articles according to the checklist of "assessment of multiple systematic reviews" (AMSTAR) tool.

RESULTS

Overall, information of 110 papers was discussed in eight systematic reviews. Authors focused on cost-effectiveness of lung cancer treatments in five systematic reviews. Targeted therapy options (bevacizumab, Erlotinib and Crizotinib) show an acceptable cost-effectiveness. Results of three studies failed to show cost-effectiveness of screening methods. None of the studies had used the meta-analysis method. The Quality of Health Economic Studies (QHES) tool and Drummond checklist were mostly used in assessing the quality of articles. Most perspective was related to the Payer (64 times) and the lowest was related to Social (11times). Most cases referred to Incremental analysis (82%) and also the lowest point of referral was related to Discounting (in 49% of the cases). The average quality score of included studies was calculated 9.2% from 11.

CONCLUSIONS

Targeted therapy can be an option for the treatment of lung cancer. Evaluation of the cost-effectiveness of computerized tomographic colonography (CTC) in lung cancer screening is recommended. The perspective of the community should be more taken into consideration in studies of cost-effectiveness. Paying more attention to the topic of Discounting will be necessary in the studies.