In the last decade, betel-quid has been classified as a Group 1 carcinogen by the International Agency for Research on Cancer [ 6, 8].
Betel quid chewing has been practised for hundreds of years, with more than 10% of the world's population chewing betel quid daily [ 8].
History of betel quid chewing has been significantly found to increase the likelihood of smoking commencement.
This paper only focuses on smoking behaviour, while data on betel quid chewing has been published previously [ 22].
In addition to tobacco smoking and alcohol drinking, betel quid chewing has been identified as a significant etiological factor in this area [ 3].
Betel quid chewing has been practiced for centuries and it is the fourth typical habit in the world after nicotine, alcohol and caffeine consumption [ 21] with an estimate of 600 million betel quid chewers worldwide [ 22].
Betel quid chewing has been associated with oral submucous fibrosis, oral cancer [ 2, 3] as well as cancer of the esophagus, liver, pancreas, larynx, and lungs; type 2 diabetes mellitus; cardiovascular disease; and adverse pregnancy outcomes [ 3– 7].
However, to date, most research on betel-quid chewing has been limited to epidemiological and biological investigations [ 9, 10].
Betel-quid chewing has been linked to oral cancer, esophageal cancers, obesity [ 22], periodontal disease [ 23], and cardiovascular disease [ 24].
The pattern of drinking and smoking is similar in both genders, but betel-quid use has been much higher in males than females [ 33].
