Mouth cancer risk factors Lifetime risk The estimated lifetime risk of being diagnosed with mouth cancer is around 1 in 55 (2%) for males, and 1 in 108 (less than 1%) for females born after 1960 in the UK. Smoking Around one in six (17%) mouth cancers are directly caused by smoking. The risk of being diagnosed with mouth cancer for a smoker is almost double (91%) that of a never-smoker. Mouth cancer risk is 35% lower in ex-smokers who quit 1-4 years previously, compared with current smokers. Mouth cancer risk is no higher in ex-smokers who quit 20+ years previously, compared with never-smokers. Mouth cancer risk is around 3 times higher in bidi smokers compared with bidi never-smokers. Smokeless tobacco Mouth cancer risk is up to four and a half times higher in smokeless tobacco users. This risk may be higher in females and for users of chewing types of smokeless tobacco. Alcohol Those who drink more than 10 units of alcohol a week could be increasing the risk of mouth cancer by 81%. Drinking alcohol to excess is linked to around a third (34%) of all mouth cancers. If you both smoke and drink to excess it can increase your risk of developing mouth cancer can be tripple. Human papillomavirus (HPV) The human papillomavirus (HPV) type-16 and 18 are linked to around three in four (73%) oropharyngeal cancers and more than one in ten (12%) oral cavity and hypopharynx cancers. Environmental tobacco smoke (ETS) Mouth cancer risk is 87% higher in never-smokers who have ever been exposed to ETS at home or work, compared with unexposed never-smokers. Mouth cancer risk is more than twice higher in never-smokers exposed to ETS at home or work for 15+ years, compared with unexposed never-smokers. Infections Mouth cancer risk is around twice higher in people with HIV/AIDS, compared with the general population. Organ transplant Mouth cancer risk is 2-5 times higher in organ transplant recipients compared with the general population. Family history Mouth cancer risk could be up to 70% higher in people with a family (particularly sibling) history of mouth cancer, versus those without such history, a pooled analysis showed.