Tobacco use is the leading cause of preventable disease, disability, and death in the United States.

CDC, 2021

For most of us, we’ve been told about the dangers of tobacco and its detrimental effects on our health since we were children. The cat’s been out of the bag on tobacco for a while now – and there’s no shortage of data and evidence that shows what it does to us. While many may associate smoking cigarettes with lung cancer, there’s a number of affects that the wacky tobacc-y has on our oral health. In this post, let’s explore the research behind tobacco, and how it can act synergistically with alcohol to cause oral cancer. From smoking it to chewing it, tobacco has a significant impact on our health.

‘WARNING: This Product May Cause Cancer’

Let’s get this out of the way – if you smoke cigarettes you are at a greater chance for lung disease, heart disease, and even diabetes (among other things)¹. This includes lung cancer – smoking accounts for more than 90% of lung cancer deaths. But what does tobacco do to our oral health, and does it cause oral cancer? Let’s start with malignancies.

In oral pathology, we describe a precancerous lesion of the oral cavity as a ‘leukoplakia.’ This is a clinical descriptor that is used when a patch of white appears that cannot be classified as any other identifiable disease. It may seem vague, but this clinical descriptor is a large red flag and the lesion is assumed as a precancerous or premalignant lesion². Because leukoplakias are the most common form of precancer, it’s important that a clinician is able to distinguish between leukoplakias and other forms of white lesions. This doesn’t mean you should be worried about every white patch you see in your mouth, though. If you see one that doesn’t disappear after a number of weeks this should warrant a visit to the dentist – especially if you smoke. Here’s why –

Smoking is the most closely associated risk factor of leukoplakias. According to Oral and Maxillofacial Pathology, more than 80% of patients who have leukoplakias are smokers².

Leukoplakias can develop into cancers. This is where things get nasty – oral cancer is deadly when not dealt with early and smoking is closely associated with it. The most common oral cancer is known as squamous cell carcinoma – it’s the main cancer we will be focusing on in today’s post. Squamous cell carcinoma accounts for more than 90% of oral malignancies². The cause for oral cancer is multi-factoral, meaning we don’t know the exact etiology of what causes it. However, there are significant risk factors, including – tobacco smoke, alcohol, and sunlight (cancers of the lip). Like we mentioned above, this cancer has been strongly associated with a preceded lesion of leukoplakia, though it has been known to present itself in many different ways. The appearance is generally white or red, growing quickly, and can become burrowing or ulcerated. This variance in form is why oral cancer is hard to diagnose and can quickly become deadly. It is often found on the floor of the mouth, as well as on the sides of the tongue.

Will Smoking Give Me Oral Cancer?

Squamous cell carcinoma is multifactorial – just because you present with one factor doesn’t mean you will get cancer. That being said, we are here to talk about the effect of tobacco on oral cancer. According to a journal review in 2010 estimating the risks of tobacco use, a meta-analysis was performed and evaluated a cancer risk 3.43 times higher in smokers than with non-smokers³. It was found that the major contributing factor of cigarette smoking is due to the carcinogens identified in tobacco smoke that leach into saliva⁴. These components are known as nitroso-nor-nicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-
1-butanone (NNK). Although they are in some forms of smokeless tobacco, these are primarily released during the burning of the cigarettes (pyrolysis)⁴.

What is interesting is the effect that smoking has when alcohol is used together with tobacco, ‘Alcohol synergizes with tobacco as a risk factor for all upper aerodigestive tract squamous cell carcinoma⁴.’ There is well-established evidence that the two used together greatly increases your chance for oral cancer⁷. It’s important to understand that alcohol alone is a risk factor for cancer, as well –

‘Furthermore, even after controlling for tobacco use, epidemiologic studies have reported a twofold to fourteenfold increased risk for oral cancer among heavy drinkers².’

So Smoking Can Cause Oral Cancer, What About Dipping?

This is a stickier subject and we are going to try to clear things up using evidence. There are multiple forms of chewing tobacco and each have different ways of manufacturing/ different chemicals (which is why this topic is hard to discuss). Let’s see what our friends at the FDA have to say about it –

‘More than 30 chemicals in smokeless tobacco are linked to cancer.’ (FDA, 2020)

This is an interesting quote, so I decided to look up the source from which it came, which was found to be Smokeless Tobacco and Public Health: A Global Perspective, GST Report. This is a comprehensive document that has all you need to know about smokeless tobacco. The document does indeed conclude based on various studies that ‘there is a casual relationship between oral cancer and smokeless tobacco including snuff, chewing tobacco, naswar, shammah, and toombak, but the risks vary substantially across products and regions including dosage and use.’ The document then goes on to say – ‘In contrast, although increased risks were observed in some studies of Scandinavian snus, most evidence from Swedish studies does not support a causal association between snus use and oral cancer⁵.’

The evidence isn’t exactly as clear as the FDA states – another review concluded that ‘available data suggest at most a minor increased risk of oral cancer associated with the use of western chewing tobacco and snuff’ – though these increases were only seen in studies before the 1980’s. In fact, when the meta-analysis adjusted for smoking and alcohol use, no excess risk was seen. The authors in this same analysis believed publication bias was present⁶

So what’s the conclusion? Smokeless tobacco has many different forms, and there are different types that absolutely have been linked to being carcinogenic (look up betel quid). However, there’s not a great amount of research that specifically links American chewing tobacco to oral cancers – but not a lot that refute it, either. That doesn’t mean there aren’t other issues with chewing tobacco, though, and this is a great time to review it.

So What Else Does Tobacco Do To Our Mouths?

There’s plenty – along with a host of pathological lesions such as hairy tongue and nicotinic stomatitis, smoking can cause an increased incidence of the bacteria that cause cavities in your mouth⁸. Smoking is one of the biggest contributors to periodontal disease, causing gingival recession that is unrepairable without surgery⁹. Smoking also has a significant impact on the prognosis of an implant – if you smoke, your implant has a greater chance to fail or develop peri-implantitis¹⁰. There’s even a greater chance for dry sockets after an extraction when an individual smokes¹¹. Some of these are mirrored by smokeless tobacco – some products have sugar in them which soaks in your mouth as you chew and provides an environment for bacteria to thrive. The friction of smokeless tobacco along your gums also promotes gingival recession, which is why you should switch sides if you do choose to dip.

‘Among a total of 4000 surgically removed mandibular third molars, patients who smoked a half-pack of cigarettes a day had a four- to five-fold increase in dry sockets (12% versus 2.6%) when compared to nonsmokers’

Alveolar Osteitis; Kolokythas et al, 2010

There’s not a lot of reasons to start smoking, especially not for your oral health. It’s up to you to use the evidence you find using reputable resources for your own personal liberties – and I’m here to help!

To Summarize:

• Smoking is bad for your overall health
• There is a strong correlation between smoking tobacco and oral cancer
• There is a strong synergistic effect between smoking tobacco and alcohol for oral cancer
• There are many forms of smokeless tobacco, but the debate is still up for whether American dip has a strong correlation for causing cancer
• Smoking has been linked to cavities, gum disease, and other oral pathologies
• Chewing has been linked to cavities and gingival recession

References:

¹CDC. (2020, September 21). Tobacco use. Retrieved February 15, 2021, from https://www.cdc.gov/chronicdisease/resources/publications/factsheets/tobacco.htm#:~:text=secondhand%20smoke%20exposure.-,Tobacco%20use%20is%20the%20leading%20cause%20of%20preventable%20disease%2C%20disability,200%20become%20daily%20cigarette%20smokers.

²Chi, A., Neville, B., Damm, D., Allen, C. (052015). Oral and Maxillofacial Pathology, 4th Edition. [VitalSource Bookshelf 9.4.3]. Retrieved from vbk://9781455770526

³Warnakulasuriya, S., Dietrich, T., Bornstein, M. M., Casals Peidró, E., Preshaw, P. M., Walter, C., Wennström, J. L., & Bergström, J. (2010). Oral health risks of tobacco use and effects of cessation. International dental journal, 60(1), 7–30.

⁴Johnson, N. (2001). Tobacco Use and Oral Cancer: A Global Perspective. Journal of Dental Education, 65(4), 328.

⁵National Cancer Institue, Centers for Disease Control and Prevention, US Department of Health and Human Services. (2014). Smokeless tobacco and Public Health: A global perspective … Retrieved February 15, 2021, from https://cancercontrol.cancer.gov/sites/default/files/2020-06/chapter_2_smokelesstobaccoandpublichealth.pdf

⁶Weitkunat, R., Sanders, E. & Lee, P.N. Meta-analysis of the relation between European and American smokeless tobacco and oral cancer. BMC Public Health 7, 334 (2007). https://doi.org/10.1186/1471-2458-7-334

⁷Mello, F. W., Melo, G., Pasetto, J. J., Silva, C., Warnakulasuriya, S., & Rivero, E. (2019). The synergistic effect of tobacco and alcohol consumption on oral squamous cell carcinoma: a systematic review and meta-analysis. Clinical oral investigations, 23(7), 2849–2859. https://doi.org/10.1007/s00784-019-02958-1

⁸Wu, J., Li, M., & Huang, R. (2019). The effect of smoking on caries-related microorganisms. Tobacco induced diseases, 17, 32. https://doi.org/10.18332/tid/105913

⁹Gautam, D. K., Jindal, V., Gupta, S. C., Tuli, A., Kotwal, B., & Thakur, R. (2011). Effect of cigarette smoking on the periodontal health status: A comparative, cross sectional study. Journal of Indian Society of Periodontology, 15(4), 383–387. https://doi.org/10.4103/0972-124X.92575

¹⁰Kasat, V., & Ladda, R. (2012). Smoking and dental implants. Journal of International Society of Preventive & Community Dentistry, 2(2), 38–41. https://doi.org/10.4103/2231-0762.109358

¹¹Kolokythas, A., Olech, E., & Miloro, M. (2010). Alveolar osteitis: a comprehensive review of concepts and controversies. International journal of dentistry, 2010, 249073. https://doi.org/10.1155/2010/249073