Defining the Risk of Oral Tobacco Products

A Sensible Medicine Guest Post

We have had a few articles about non-combustible tobacco products. I’ll attribute this to interesting submissions and the possibility that these products represent a sensible alternative to a once widely used lethal product. Whether we are talking about vapes, dip, chew, or snus, these products are an interesting health challenge. Better than cigarettes, but probably worse than nothing. But, then again, a subset of any population will probably always get benefits from nicotine products.

Today’s post, the last on the topic for a while, is a response to a challenge from me, which Dr. Rodu explains.

Adam Cifu

In my recent Sensible Medicine article, “Six Urban Myths About Smoke-Free Nicotine”, I noted that American dip/chew products do not pose any appreciable risk for head and neck cancer among American men. Surprised? What follows is an explanation of the evidence for that statement.

The idea that oral, non-smoked, tobacco causes head and neck cancer can be traced directly to an NEJM article published 44 years ago.¹[i] That study, authored by Deborah Winn and colleagues, appeared the same year that I began my 24-year faculty career at the University of Alabama at Birmingham School of Medicine as an oral and maxillofacial pathologist. My job included diagnosing cancers from pathologic samples and managing the oral effects of radiation and chemotherapy. I saw hundreds of mouth cancer cases over the years, mostly attributed to smoking and/or heavy alcohol use. Human papillomaviruses (HPVs) were recognized much later (in 2007) by the International Agency for Research on Cancer as causing oropharynx cancer.

By the early 1990s, I had identified what FDA commissioner Marty Makary described in his recent book as a “blind spot” between the almost universal perception that chewing tobacco causes head and neck cancer and my own experience. I had not diagnosed or treated mouth cancer in men who exclusively used oral tobacco. I had, however, seen mouth cancers among women who used powdered dry snuff. Dry snuff is a completely different (see below) oral product. It is also the only product used by the Southern women in Winn’s study.

An announcement in December 1992 from U.S. Surgeon General Antonia Novello was the catalyst for my research: She predicted an oral cancer epidemic if “spit tobacco use” [sic] continued (here). Dr. Novello’s announcement led to my first journal articles in 1994 (here and here), and my book, “For Smokers Only” in 1995.

Winn’s study was consistent with the 116 mouth cancer cases reported in an a 1991 NIH monograph on smokeless tobacco and health, and with my experience: some elderly women who use powdered dry snuff get oral cancer, at the site of placement, after decades of use. In Winn’s study, however, the exposure was not well defined. Her article, and the subsequent coverage, did not mention that the women’s exposure was exclusively powdered dry snuff. Dr. Winn, herself, later acknowledged this error years later, but her admission appeared in only two obscure scientific publications.

By 2002, epidemiologist Philip Cole and I had published a comprehensive review of oral tobacco and mouth cancer that distinguished between types of tobacco used. We found that the “use of moist snuff and chewing tobacco is associated with small risk for cancers of the oral cavity and other upper respiratory sites, with relative risks ranging from 0.6 to 1.7. The use of dry snuff is associated with much higher risk, ranging from 4 to 13.” Winn’s relative risk calculation for dry snuff was 4.2.

In 2004, I published a laboratory analysis explaining why dry snuff’s cancer risk was high. Working with a scientist at the Swedish National Food Administration, I found that levels of cancer-causing tobacco-specific nitrosamines (TSNAs) in Swedish snus and American dip/chew were low, but levels in powdered dry snuff were 100 to 500 times higher.

In 2016, Annah Wyss and colleagues – including Deborah Winn – published a meta-analysis of oral tobacco use and oral-pharynx cancer. They found that American men had no excess mouth cancers associated with dip or chew tobacco (Odds Ratio, OR = 0.9), while women, who mainly use powdered dry snuff, had an OR = 9. While that ten-fold difference should have been the headline, it wasn’t even mentioned in the abstract. Instead, the authors emphasized average ORs of men and women combined.

In summary, while using dip or chew is not perfectly safe as a way of consuming nicotine, it is vastly safer than burning tobacco and inhaling smoke.

Dr. Cifu said he’d have a hard time buying this argument because he associates chewing tobacco with head and neck cancer among baseball greats. I’ll finish with some perspectives about famous baseball players Babe Ruth, Tony Gwynn and Curt Schilling, whose cancers were promoted widely as being caused by dip/chew.

It is a decades-old myth that Babe Ruth suffered from oral tobacco induced mouth cancer. In addition to chewing tobacco, he was a prodigious consumer of cigars and alcohol. However, none of these are associated with Ruth’s diagnosis of nasopharyngeal carcinoma (discussed here), a rare malignancy caused by the Epstein-Barr virus.

Tony Gwynn died from salivary gland cancer. Data from the National Cancer Institute’s Surveillance Epidemiology and End Results (SEER) program reveal about 23 cases per million men each year; it is a very rare cancer. Epidemiologic studies have not established a definitive cause, but they show that radiation therapy, alcohol use, and hair dyes are possible risk factors. Tobacco use is not even mentioned.

Curt Schilling claimed that his mouth cancer was caused by oral tobacco use, but his causal claim was never supported by his medical team. In fact, it’s unlikely that he had mouth cancer, which occurs in the lip or cheek at the site of dry snuff placement. He told the press that his cancer was discovered after he found a lump in his neck. This indicates that the primary cancer was in his posterior tongue, tonsils, pharynx, or was not found. Those cancers are strongly linked to smoking, heavy alcohol use, and HPV infection.

I sympathize with these individuals and their families, but misrepresenting their stories obscures the fact that the number one cancer killer is cigarette smoking. Exaggeration and distortion of risks related to use of smoke-free nicotine and tobacco is more than a disservice to ballplayers, dippers, and chewers, as it dissuades inveterate smokers from making a life-saving switch.

Brad Rodu is a Professor of Medicine at the University of Louisville, holds an endowed chair in tobacco harm reduction research, and is a member of the James Graham Brown Cancer Center at U of L.

1. To clarify terms: oral tobacco products can mean dip (moist snuff) or chew (chewing tobacco) and powdered dry snuff. OT will mean dip and chew while dry snuff will be differentiated.