Betel nut (Areca catechu) is 'chewed' (held in the mouth and sucked) widely in South and Southeast Asia. It is associated with throat, mouth, and oesophagal cancers and there have been a number of laboratory and survey research projects which appear to positively tie betel use with these cancers.

Betel is also used in mixtures often called "Pan Masala" which is sometimes added to chewing tobacco and sometimes used without tobacco. Research into the use of Pan Masala, both with and without tobacco, indicate that Betel likely causes throat and mouth cancers with prolonged use. (See Chaudry 1999)

Cultural & Dietary Risk Factors of Oral Cancer and Pre-Cancer-- a brief overview, Zain RB 2001

Pub Med Search Results on "Betel Nut Cancer"