Improving Utility of Data on Cancer Mortality Risk Associated with Smokeless Tobacco: Recommendations for Future Research

Rakhi Dandona,Manu Raj Mathur,Lalit Dandona,G Anil Kumar

doi:10.31557/apjcp.2019.20.2.581

Abstract

Background:We analyzed in detail the studies utilized in most recent global systematic review of risk of cancer mortality with smokeless tobacco (SLT) use to report challenges in the available data that limit the understanding of association between SLT use and cancer mortality. Methods:For each study, we documented study design, reporting of mortality risk by type of SLT variant, SLT use frequency, and sex of SLT user for oral, oesophageal, pharyngeal, laryngeal and orolaryngeal cancers. These findings are discussed within the context of prevalence of SLT use by geographic regions and sex. Results:Majority of studies reported mortality risk for oral (70.6%) followed by oesophageal cancer (38.2%). The availability of population-based evidence was low (35.3%). The geographic distribution of studies did not reflect the geographic distribution of countries with high SLT consumption; 61.8% of the studies were from India followed by Sweden (20.6%). Hospital-based (84.2%) studies reported risk with chewing tobacco and the population-based studies (61.5%) with non-chewing tobacco. Hardly any study reported on a particular type of SLT. Definition of SLT use as current, ever or former was limited without consideration of the wide variations in frequency and duration of use within these patterns. Mortality risk reporting for males dominated all cancers other than oral (50% males). Conclusions:Unless the methodological and generalizability challenges identified in this review are addressed in future research to develop a stronger scientific basis of the association of SLT use and cancer mortality, we would continue to face significant challenges in monitoring the health effects of SLT.

Highlights

Smokeless tobacco (SLT) consists of a number of products containing tobacco, which are consumed without burning through the mouth or nose (Centre for Disease Control., 2002)
The geographic distribution of studies did not reflect the geographic distribution of countries with high smokeless tobacco (SLT) consumption; 61.8% of the studies were from India followed by Sweden (20.6%)
A total of 34 studies were considered for association between SLT use and cancer mortality (Table 1) of which, 24 (70.6%) studies reported on association with oral cancer followed by that with oesophageal cancer (n=13; 38.2%)

Summary

Introduction

Smokeless tobacco (SLT) consists of a number of products containing tobacco, which are consumed without burning through the mouth or nose (Centre for Disease Control., 2002). There are a number of biochemical studies showing the presence of carcinogens in various commercially available SLT products, the epidemiological evidence assessing the association between SLT use and cancer mortality is very limited and often not very robust. This lack of strong evidence from major SLT consuming countries has put forward a number of policy challenges seriously affecting efforts to control SLT consumption. Methods: For each study, we documented study design, reporting of mortality risk by type of SLT variant, SLT use frequency, and sex of SLT user for oral, oesophageal, pharyngeal, laryngeal and orolaryngeal cancers. Conclusions: Unless the methodological and generalizability challenges identified in this review are addressed in future research to develop a stronger scientific basis of the association of SLT use and cancer mortality, we would continue to face significant challenges in monitoring the health effects of SLT

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