Tuesday, May 8, 2012

Smokeless Tobacco Not a Risk Factor for Cancer of the Salivary Glands

Two celebrities -- Adam Yauch ("MCA" of the Beastie Boys) and Tony Gwynn (Hall of Fame baseball player) -- were recently reported to have suffered salivary gland cancer. This has prompted questions about tobacco use as a possible risk factor.

Cancer of the salivary gland is exquisitely rare. For perspective, data from the Surveillance Epidemiology and End Results (SEER) program at the National Cancer Institute reveal that there were only about 34 cases of oral/throat cancer annually among 100,000 men ages 40-84 years from 2001 to 2006 (see my recent post here).

In comparison, SEER data show a mere 2.3 cases of salivary gland cancer within that group, or 23 cases per million men.

Few epidemiologic studies have looked at tobacco use as a risk factor for salivary gland cancer; most are from the 1990s. Researchers from the M.D. Anderson Cancer Center in 1990 found that tobacco use was not a risk factor in an analysis of 64 cases (abstract here). They did find that a history of radiation therapy was a risk factor in both men and women (odds ratio, OR = 2); among women, high education, alcohol and use of hair dyes doubled the risk.

A 1997 report based on 141 cases suggested that smoking elevated the risk of salivary gland cancer (abstract here), but it the increase wasn’t statistically significant (OR = 2.1, 95% confidence interval = 0.98 – 4.7). That study confirmed the risk for radiation, and also reported that occupational exposure to nickel compounds (OR = 6) and heavy alcohol use (OR = 2.5) were significant risk factors.

In a 1998 study involving 128 cases of salivary gland cancer (abstract here), investigators reported that “Cigarette smoking and alcohol consumption did not independently or jointly increase the risk of salivary gland cancer. Chewing tobacco and snuff use were also unrelated factors.”

In summary, there is little evidence that smoking is a risk factor for salivary gland cancer. For smokeless tobacco, there is no evidence.

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