What causes oral leukoplakia?

The exact cause of oral leukoplakia is still unknown, although certain risk factors have been identified. More
than 80% of patients with oral leukoplakia have a history of tobacco use and the condition is six times more
common among smokers than non-smokers. Other risk factors include excessive alcohol use (especially in
people who also smoke), a weakened immune system, long-term treatment with immune suppressing
medications, a history of cancer, a family history of cancer, and in some cultures, the chewing of areca nut and
betel leaf.