Users of smokeless tobacco are up to four and a half times more likely to develop cancer of the hypopharynx -- the part of the throat just above the voicebox -- than nonusers, Reuters reported Sept. 13.

The smokeless tobacco used in India is mixed with slaked lime and comes in five forms: pan, khaini, Guthka, mawa, and zarda. For these products, risk of hypopharyngeal cancer was elevated by a factor ranging from 2.85 to 4.59, Indian researchers reported. The researchers noted increased concern about the dangers of smokeless products as smokers increasingly turn to alternatives in the mistaken belief that they are safer products.

Researcher Amir Sapkota and colleagues found that smokeless tobacco users were not at higher risk of larynx cancer. "Direct and prolonged contact is necessary for the effect of chewing tobacco to manifest," they noted.

The study was published in the Oct. 15, 2007 issue of the International Journal of Cancer.