The causation of oral precancer and cancer.

Most cases of oral cancer result from the action of exogenic carcinogenic agents, some of which act synergistically in producing their effects. The evidence implicating tobacco and alcohol abuse is overwhelming and cannot be refuted. Other clearly identifiable aetiological agents include betel nut chewing and excessive exposure to sunlight. While there is increasing evidence of a viral causation, this is not yet clearly established. Similarly, the role of Candida albicans remains uncertain. Lichen planus and discoid lupus erythematosus may constitute important predisposing conditions, but the documentation remains inadequate and inconclusive, as does that implicating electrogalvanism. Tertiary syphilis is no longer considered a significant factor in oral cancer. Sideropenic dysphagia and haemoglobin and serum iron deficiencies may be of importance in the development of oral carcinoma, particularly in elderly women with no history of tobacco and alcohol abuse. The roles of poor oral hygiene and sharp edges of teeth and dentures have probably been overemphasized in the past.