Biological and epidemiologic updates on lip and oral cavity cancers

Oral cavity cancers develop from a specific anatomic area extending from the lips within a circular region at the back, encompassing the circumvallate papillae on the tongue dorsum, the frontal tonsil pillars, up to the junction of hard and soft palate. The vast majority of these cancers, up to 85–95%, are squamous cell carcinomas, often developing from pre-existing precancerous lesions. Oral cavity cancers mostly develop from the floor or anterior base of the mouth, whilst ~90% of lip tumors develop from the lower lip. The current cumulative age-standardized incidence of lip and oral cancers is 4.0 per 100,000, more than double in men than in women (5.8 vs. 2.3 per 100,000, respectively). The incidence, which exponentially grows in parallel with ageing in both sexes, is the highest in Oceania and the lowest in Africa. The cumulative age-standardized mortality for lip and oral cancers is 2.0 per 100,000, again more than double in men than in women (2.8 vs. 1.2 per 100,000, respectively). Likewise incidence, mortality also grows in parallel with ageing and is the highest in Asia. The cumulative risk of death is the highest in Africa, where the ratio between deaths and incidence new cases is 70%. Alcohol and cigarette smoking are both responsible for the highest number of deaths in men (>80%), whilst chewing tobacco seems to cause the highest number of deaths in women (>50%). The cumulative 5-year relative survival rates for cancers of lip, tongue and floor of the mouth are 88%, 66% and 53%, respectively. It can be finally estimated that incidence and mortality for these cancers will perhaps exhibit an approximately 2-fold increase by the year 2050.