Characteristics of oral squamous cell carcinoma focusing on cases unaffected by smoking and drinking: A multicenter retrospective study

Background: Some oral squamous cell carcinoma (OSCC) cases are unaffected by smoking or drinking. This study aimed to clarify distinctive groups among OSCC patients and examine the characteristics of multiple primary carcinomas (MPCs). Methods: We analyzed data from 970 patients. The patients were divided into three groups: all individuals <45 years (<45 y), smokers/drinkers ≥45 years (SD ≥45 y), and non-smokers/non-drinkers ≥45 years (NSND ≥45 y). Results: Tongue cancers were more common in the <45 y group than in the other groups (p < 0.001). The NSND ≥45 y group was significantly older and more likely to be female than the SD ≥45 y group (p < 0.001). MPCs in the upper aerodigestive tract were more common in men and smokers/drinkers, whereas women were at risk for multiple primary OSCCs (p = 0.022). Conclusions: The “young tongue” and “elderly female” subgroups and characteristics of MPCs suggest carcinogenic factors of OSCC other than smoking and drinking.