Invited Commentary: Smokeless Tobacco—An Important Contributor to Cancer, but More Work Is Needed

American Journal of Epidemiology, Nov 2016

In this issue of the Journal, Wyss et al. (Am J Epidemiol. 2016;184(10):703–716) describe the association between use of smokeless tobacco and head and neck cancer in 11 US case-control studies. Despite use by an estimated 300 million people worldwide and prior evidence for a causal association with cancer, these products remain understudied. Data are particularly needed for persons who do not use cigarettes or other smoking tobacco products. With 6,772 cancer cases and 8,375 controls, the current study is larger than previous efforts, allowing evaluation of associations among never cigarette smokers. Importantly, snuff use was positively associated with head and neck cancer, particularly for cancers of the oral cavity, whereas associations were weaker for chewing tobacco. Associations were observed among never cigarette smokers but not among ever cigarette smokers. Yet, despite the large sample size, only 44 cases and 62 controls had used snuff and only 61 cases and 96 controls had used chewing tobacco in the absence of cigarettes, precluding detailed examinations of dose response and cessation. Future studies set in high-prevalence populations with detailed assessment of lifetime use are needed to better understand the cancer risks of exclusive smokeless tobacco use and dual use of smokeless tobacco with other tobacco products, including cigarettes.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://aje.oxfordjournals.org/content/184/10/717.full.pdf

Invited Commentary: Smokeless Tobacco—An Important Contributor to Cancer, but More Work Is Needed

Am J Epidemiol. Invited Commentary: Smokeless Tobacco-An Important Contributor to Cancer 0 but More Work Is Needed 0 Neal D. Freedman ) 0 0 Medical Center Way , MSC 9768, Rockville, MD 20850 ( American Journal of Epidemiology © Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US. In this issue of the Journal, Wyss et al. (Am J Epidemiol. 2016;184(10):703-716) describe the association between use of smokeless tobacco and head and neck cancer in 11 US case-control studies. Despite use by an estimated 300 million people worldwide and prior evidence for a causal association with cancer, these products remain understudied. Data are particularly needed for persons who do not use cigarettes or other smoking tobacco products. With 6,772 cancer cases and 8,375 controls, the current study is larger than previous efforts, allowing evaluation of associations among never cigarette smokers. Importantly, snuff use was positively associated with head and neck cancer, particularly for cancers of the oral cavity, whereas associations were weaker for chewing tobacco. Associations were observed among never cigarette smokers but not among ever cigarette smokers. Yet, despite the large sample size, only 44 cases and 62 controls had used snuff and only 61 cases and 96 controls had used chewing tobacco in the absence of cigarettes, precluding detailed examinations of dose response and cessation. Future studies set in high-prevalence populations with detailed assessment of lifetime use are needed to better understand the cancer risks of exclusive smokeless tobacco use and dual use of smokeless tobacco with other tobacco products, including cigarettes. case-control studies; cigarettes; head and neck neoplasms; smokeless tobacco Abbreviations: CI, confidence interval; OR, odds ratio. - An estimated 300 million people worldwide use smokeless tobacco products (1), with nearly 90% of use occurring in Southeast Asia. In the United States, approximately 2.6% of adults (4.8% of men and 0.3% of women) currently use smokeless tobacco products (2). However, substantial geographic variation is observed, with the prevalence of current use ranging from 1.5% in the District of Columbia and Massachusetts to 9.4% in West Virginia (3). Whereas the adult prevalence of cigarette smoking has declined in the United States over time (4), the prevalence of smokeless tobacco use among US adults has been largely stable over the last 10 years (5). Smokeless tobacco use is also common among youth, with recent data indicating that 9.9% of male high school students and 1.2% of female high school students had used it in the past 30 days, compared with 10.6% of male students and 7.9% of female students who smoked cigarettes (6). Smokeless tobacco contains nicotine as well more than 30 carcinogens, such as tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons (1, 7). The International Agency for Research on Cancer has determined that smokeless tobacco products are carcinogenic to humans and that such products are causally related to cancers of the oral cavity, esophagus, and pancreas (8). Nevertheless, far less information is available on the health effects of smokeless tobacco than is available for cigarette smoking. Perhaps the greatest amount of data is available for cancers of the oral cavity and overall head and neck. Yet even here, there are many remaining research questions. Smokeless tobacco products also differ substantially around the world, varying in chemical composition and in the way that they are used (1), necessitating a range of studies that carefully assess associations with different types of tobacco products. Within the United States and elsewhere, previous studies have often been limited by small sample sizes and have lacked comprehensive assessment of lifetime use patterns. Many smokeless tobacco users in these studies also used cigarettes, which has made it challenging to define the risks of exclusive smokeless tobacco use. Within this context, the paper by Wyss et al. (9) in this issue of the Journal provides important information on the association of smokeless tobacco products with head and neck cancer. The study is set within the International Head and Neck Cancer Epidemiology Consortium and includes data from 11 US case-control studies, representing 6,772 cancer cases and 8,375 controls. The large sample size of this study provides numerous advantages, including the possibility of investigating associations among never cigarette smokers and within subsites of head and neck cancer. Importantly, among never cigarette smokers, ever users of snuff had higher risks of head and neck cancer (odds ratio (OR) = 1.71, 95% confidence interval (CI): 1.08, 2.70), particularly for oral cavity cancer (OR = 3.01, 95% CI: 1.63, 5.55) (9). Associations for ever use of chewing tobacco among (...truncated)


This is a preview of a remote PDF: https://aje.oxfordjournals.org/content/184/10/717.full.pdf

Neal D. Freedman. Invited Commentary: Smokeless Tobacco—An Important Contributor to Cancer, but More Work Is Needed, American Journal of Epidemiology, 2016, pp. 717-719, 184/10, DOI: 10.1093/aje/kww076