Squamous cell carcinoma of the mobile tongue in young adults: A Swedish head & neck cancer register (SweHNCR) population-based analysis of prognosis in relation to age and stage.

Increased incidence of squamous cell carcinoma (SCC) of the tongue has been reported in young adults (YA) in several countries since the 1980s and confirmed in later studies. The etiology is unclear, the prognosis has been debated, and conflicting results have been published. Some studies show better survival in young adults than in older patients, some worse, and others no difference. Most studies are based on selected series or include other sites in the oral cavity. The definition of "YA" is arbitrary and varies between studies. It is thus difficult to use in general conclusions. This work uses data from the population-based Swedish Head and Neck Cancer register (SweHNCR), which has > 98% coverage. SweHNCR data includes age, gender, TNM, treatment intention, treatment given, lead times, performance status, and to a lesser degree, smoking habits. The current Swedish population is around 10 million. We analyzed outcomes for 1416 patients diagnosed with SCC of the oral tongue from 2008 to 2017 using 18-39 years to define YA age because it is the range most commonly used. We found no significant difference in relative survival (a proxy for diagnosis-specific survival) between age groups of patients treated with curative intent for SCC of the oral tongue. The stage at time of diagnosis was equally distributed among the age groups. Excess mortality rate correlated mainly with stage, subsite of the tongue, performance status, and lead time to treatment.