Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. Implications for treatment modality selection.

We reviewed all studies since 1940 on the prognosis of squamous cell carcinoma (SCC) of the skin and lip. The following variables are correlated with local recurrence and metastatic rates: (1) treatment modality, (2) prior treatment, (3) location, (4) size, (5) depth, (6) histologic differentiation, (7) histologic evidence of perineural involvement, (8) precipitating factors other than ultraviolet light, and (9) host immunosuppression. Local recurrences occur less frequently when SCC is treated by Mohs micrographic surgery. This local recurrence rate differential in favor of Mohs micrographic surgery holds true for primary SCC of the skin and lip (3.1% vs 10.9%), for ear SCC (5.3% vs 18.7%), for locally recurrent (previously treated) SCC (10% vs 23.3%), for SCC with perineural involvement (0% vs 47%), for SCC of size greater than 2 cm (25.2% vs 41.7%), and for SCC that is poorly differentiated (32.6% vs 53.6%).