September 13, 2007 / 6:29 PM / 10 years ago

Smokeless tobacco use linked to throat cancer

CHENNAI, India (Reuters Health) - A study from India shows that use of smokeless tobacco in the form of chewing tobacco or snuff is associated with an increased risk of developing cancer in the “hypopharynx” -- the area at the back of the throat immediately above the larynx, or voicebox.

The increasing popularity of smokeless tobacco is a cause for concern, Dr. Amir Sapkota and colleagues write in the October 15th issue of the International Journal of Cancer. Chewing tobacco is consumed in India in the form of pan, khaini, guthka, mawa or zarda -- all of which contain tobacco and slaked lime as their main components. Snuffing of tobacco, alone or mixed with slaked lime (naswar) either through nose or mouth, is also popular, they explain.

Sapkota and colleagues studied 1,024 patients with various head and neck cancers and 718 healthy controls from four major cancer centers in India.

Among non-smokers, smokeless tobacco use was associated with a significantly higher risk of cancers of the hypopharynx but not of cancers of the larynx, the researchers report.

The odds ratio for hypopharyngeal cancers was 2.85 among tobacco snuff users, which increased to 3.34, 3.58 and 4.59 among those chewing tobacco in the form of pan, zarda and guthka, respectively.

“Direct and prolonged contact is necessary for the effect of chewing tobacco to manifest,” Sapkota and colleagues postulate. This could probably explain the lack of association between smokeless tobacco and cancers of the larynx, they suggest.

The incidence of upper airway cancers is on the rise in India, Sapkota and colleagues note. “The increasing usage of smokeless tobacco products combined with the ill-perceived notion that it is a relatively safe product compared to cigarettes, may pose a substantial threat to public health in the coming years.”

The researchers also point out that “the popularity of the smokeless tobacco product is growing in the North American youths as well, owing to the public usage of such products by social models.”

SOURCE: International Journal of Cancer, October 15, 2007.

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