Effects of tobacco on the DNA of smokers and non-smokers affected by OSCC: systematic review and meta-analysis

Association of Tobacco Use and Cancer Incidence in India: A Systematic Review and Meta-Analysis

PURPOSE

To estimate the strength of the association between tobacco use and cancer incidence among the Indian population.

MATERIALS AND METHODS

Data from PubMed, Embase, and Virtual Health Library were searched from inception of databases till April 30, 2022. There were no restrictions except for English language and human study. Case-control and cohort studies on cancer incidence in relation to tobacco use were selected. Data were extracted independently by two investigators, and discrepancies were resolved by a third reviewer. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. The quality assessment was done using the Newcastle Ottawa Scale.

RESULTS

The majority were case-control designs (60, 89.6%), covering diverse geographic regions, with Maharashtra (18, 30%) and Kerala (12, 20%) being the most studied. Pooled effect sizes were calculated using the random-effects model, and forest plots were generated. The risk of any cancer associated with smoked and smokeless tobacco was 2.71 (95% CI, 2.25 to 3.16) and 2.68 (95% CI, 2.22 to 3.14), respectively, indicating similar risks. Gender-wise, smoked tobacco had an association of 2.35 (95% CI, 2.05 to 2.65) for males, whereas for smokeless tobacco, it was 1.77 (95% CI, 1.47 to 2.07) for males and 2.34 (95% CI, 1.26 to 3.42) for females. Regardless of gender, tobacco type, and affected body parts, the risk of cancer due to tobacco use was consistent in the Indian population. Site-specific analysis showed higher risks of respiratory system cancers of 4.97 (95% CI, 3.62 to 6.32) and head and neck cancers of 3.95 (95% CI, 3.48 to 4.42).

CONCLUSION

This study underscores that both smoked and smokeless tobacco are equally harmful to human health among the Indian population, providing insights for stakeholders and policymakers to arrive at tobacco-specific interventions.

Comet assay as a suitable biomarker for in vivo oral carcinogenesis: a systematic review

BACKGROUND AND OBJECTIVES

In order to detect genetic damage, different methods have been developed, such as micronuclei and comet assay. The comet assay presents some advantages when compared to the other aforementioned methods, including wide versatility, as any eukaryotic cell can be evaluated at an individual cellular level. In this context, the aim of this systematic review was designed to help further elucidate the following question: is the comet assay a suitable biomarker of in vivo oral carcinogenesis?

MATERIAL AND METHODS

The present systematic review was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Full manuscripts from 18 studies were carefully selected in this setting.

RESULTS

A total of 15 studies demonstrated positive findings for genotoxicity in peripheral blood or oral cells in patients with pre-malignant lesions or oral cancer. In the quality assessment of studies, 1 was classified as Strong, 5 were considered as Moderate, and 12 were classified as Weak.

CONCLUSION

In summary, the comet assay can be a useful biomarker for oral carcinogenesis. However, further studies with more strict parameters are suggested (with less uncontrolled confounders) in order to increase findings reliability for diagnosis of oral potentially malignant lesions.