Smokeless tobacco and cancer

ROC STATUS: Known human carcinogen since 2000

ALSO KNOWN AS: Smokeless tobacco, chew, snuff, dip, plug tobacco

RELATED CANCERS: Oral cancers and cancers of the esophagus, larynx, pharynx, stomach, and bladder

DEFINITION: Often called smokeless tobacco, these tobacco and tobacco-based products that are not smoked but chewed or otherwise used in the mouth, such as chew, snuff (both oral and inhaled), dip, and plug tobacco, cause or are associated with certain cancers and other disorders of the mouth.

Exposure routes: Oral by chewing, sucking, and ingestion

Where found: Sold in the form of snuff, chewing tobacco, and plug tobacco

At risk: Users of smokeless tobacco

Many individuals use tobacco by smoking cigarettes, cigars, and pipes. Others use tobacco by chewing it. Some do not even chew it but use it by keeping it inside their mouth, such as on a cheek or between the teeth and lower lip, and absorb it by sucking on it. The tobacco products release chemicals, like nicotine, that are absorbed into the body. Relative to cigarettes, three to four times as much nicotine is absorbed into the body per dose with smokeless tobacco. Because these substances generate saliva, individuals who use them may frequently spit out the saliva and part of these products or their juices. Such products include chew, snuff, and dip.

Chew is a form of shredded tobacco leaves. Snuff is fine-grained processed tobacco with smaller particles, similar to prepared spices or tea. It is so delicate in some cases that users may inhale or sniff it rather than use it orally. Dip is another term for snuff and refers to how individuals use the material. They may dip their finger into a packet or pinch it to get a dose and place it in the mouth. Plug tobacco is similar to chew, but the tobacco is compressed into a hard plug between the cheek and gums instead of loose leaves. All dispense nicotine to the user and are classified as chewing tobacco.

Etiology and symptoms of associated cancers: Many individuals wrongly believe that not smoking avoids the normal cancer risks posed by cigarettes and cigars. However, chewing tobacco and smokeless tobacco products also carry health and cancer risks. Smokeless tobacco contains over twenty-eight known carcinogens. These cancer-causing agents include acetaldehyde, arsenic, benzo(a)pyrene, cadmium, formaldehyde, hydrazine, and nitrosamines. Nitrosamines are some of the most dangerous carcinogens in smokeless tobacco.

Oral cancers are commonly associated with such tobacco use and are somewhat of a function of the direct or close contact of the substance with parts of the mouth, such as the bones, cheeks, floor of the mouth, gums, roof of the mouth, and tongue. Users sometimes swallow juices from these products. As a result, smokeless tobacco use is associated with cancers of the esophagus, larynx, pharynx, stomach, and bladder. Most problems first appear as sores in the mouth that will not heal, difficulty swallowing or chewing, ear pain, voice changes, or sore throats that seem to persist. Another sign might be lesions or areas of discoloration, such as white patches or red sores on the gums, tongue, or cheeks. Exposed tooth roots may also occur.

History: Reports on health problems related to smokeless tobacco use date back to the eighteenth century. The use of these products is global. Over 90 percent of individuals with mouth cancers are tobacco users. Between 2 and 3 percent of the American population uses smokeless tobacco.

Many high school and middle school students learn about smokeless tobacco through its use by professional sports teams, like baseball and hockey players. Prevention efforts have focused on sports players who have endured problems related to oral cancers, telling their stories and warning students about the risks to discourage use.

Relative to women, men use significantly more smokeless tobacco. Individuals in rural areas are more likely to use smokeless tobacco, and non-Hispanic White adults have the highest prevalence of any group at 2.9 percent. Additionally, 3.2 percent of individuals in the Midwest use smokeless tobacco, while individuals in the West and Northeast have the lowest use rates at 1.6 to 1.2 percent, respectively. Oral cancers usually occur in individuals over fifty-five but may occur at any age. Tobacco use combined with alcohol use can dramatically increase the risk of cancers related to smokeless tobacco. Globally, 300,000 individuals are diagnosed with oral cancer each year.

Bibliography

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Hecht, Stephen S., and Dorothy K. Hatsukami. "Smokeless Tobacco and Cigarette Smoking: Chemical Mechanisms and Cancer Prevention." Nature Reviews Cancer, vol. 22, no. 3, 2022, pp. 143-155. doi.org/10.1038/s41568-021-00423-4.

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Noor, Ashek Elahi, and Boyapati Ramanarayana. "Relationship of Smokeless Tobacco Uses in the Perspective of Oral Cancer: A global Burden." Oral Oncology Reports, 2024. doi.org/10.1016/j.oor.2024.100516.

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