Prognostic Factors and Survival Outcomes in T1N0 Lower Lip Squamous Cell Carcinoma.

Objective: To evaluate clinicopathological factors associated with survival and recurrence in patients with T1N0 lower lip squamous cell carcinoma (LSCC), with particular attention to depth of invasion (DOI), perineural invasion (PNI), and neck management. Methods: This retrospective single-center cohort included 61 surgically treated patients with T1N0 lower LSCC. Overall survival (OS) and disease-free survival (DFS) were analyzed using Kaplan-Meier methods and Cox regression. A prespecified multivariable model included age, tumor diameter, and DOI. Exploratory recurrence analyses were also performed. Results: The cohort comprised 50 men and 11 women, with a mean age of 64.8 years. Estimated 5-year OS and DFS were 84.8% and 79.2%, respectively. Recurrence occurred in six patients (9.8%), including four local and two regional recurrences; one patient died of lower lip cancer. In univariable Cox analysis, increasing DOI was associated with worse OS (HR 1.15/mm, 95% CI 1.02-1.30; Conclusion: T1N0 lower LSCC showed low recurrence and very low disease-specific mortality. PNI showed the strongest adverse prognostic signal, although interpretation is limited by the small number of PNI-positive cases. Neck dissection was associated with improved OS and DFS in univariable analyses, but this finding should be interpreted cautiously in the context of surgeon-specific practice variation and limited event numbers. Prospective studies are needed to define risk-stratified neck management in T1N0 disease. Level of Evidence: 4.