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Epidemiology of Squamous Cell Carcinoma of the Lip in the United States: A Population-Based Cohort Analysis.

Importance
Squamous cell carcinoma of the lip (lip SCC) composes more than 25% of all oral cancers. Most of the demographic and prognostic indicators for lip SCC are only available through retrospective case series.


Objective
To examine the incidence, treatment, overall survival, and disease-specific survival (DSS) of patients with lip SCC.


Design, Setting, and Participants
Population-based cohort analysis using the Surveillance, Epidemiology, and End Results database identified patients with lip SCC between January 1, 1973, and December 31, 2012.


Main Outcomes and Measures
Overall survival and DSS.


Results
A total of 15 832 cases of lip SCC were identified. The cohort was composed of 12 945 men (81.8%) and 2887 women (18.2%). The mean age at diagnosis was 66.1 years. White patients accounted for 98.4% of the cases. Most of the tumors presented in the lower lip (77.8% external and 10.2% mucosal), whereas the external upper lip, mucosal upper lip, and the oral commissure represented 8%, 1%, and 1.2% of all cases, respectively. Of the patients, 91.2% underwent surgical therapy, 7.7% received radiation therapy, and 4.7% received both. Overall survival at 2 years, 5 years, and 10 years was 85.5%, 69.9%, and 50.2%, respectively. Multivariate analysis revealed that age, primary site, T stage, and N stage were determinants of overall survival and DSS. Kaplan-Meier survival analysis showed that SCC of the upper and lower lip had similar overall survival (163.6 months vs 163.8 months) and DSS (418.6 months vs 423.6 months). In contrast, SCC of the oral commissure had significantly lower overall survival (128.5 months) and DSS (286.7 months).


Conclusions and Relevance
Our study demonstrates that lip SCC predominantly affects white men in their mid-60s. The determinants of survival for lip SCC include age at diagnosis, primary site, T stage, and N stage. Squamous cell carcinoma of the upper lip and lower lip had similar survival, whereas SCC of the oral commissure was associated with decreased survival.