Prognostic factors for metastasis in squamous cell carcinoma of the skin

BACKGROUND. Squamous cell carcinoma (SCC) of the skin exhibits a significant propensity to metastasize. A number of variables have been reported to influence the tendency of SCC to metastasize. Because of the increasing incidence of skin cancer, it is becoming increasingly important to identify those neoplasms which are biologically more aggressive. We report 25 cases of metastatic SCC and compare them to 175 cases of nonmetastasizing SCC treated during the same period. OBJECTIVE. To characterize tumors with the greatest tendency to metastasize. METHODS. A tumor registry from the Dermatologic Surgery Unit at the Medical University of South Carolina was accessed to obtain records on 200 patients diagnosed with invasive SCC managed by Mohs surgery from 1988 to 1998. A retrospective analysis was conducted. The characteristics of patients with metastatic SCC and those with nonmetastatic SCC were compared using the chi-squared test and Fisher's exact test. RESULTS. Of 200 tumors, 25 (12.5%) metastasized. Size, Clark's level, degree of differentiation, the presence of small tumor nests, infiltrative tumor strands, single-cell infiltration, perineural invasion, acantholysis, and recurrence all correlated strongly with metastasis. Location, ulceration, inflammation, and Breslow depth did not correlate with the development of metastasis. CONCLUSION. Patients with tumors that exhibit certain clinical and histologic features are more likely to metastasize and need close follow-up to detect recurrence and metastasis early, allowing for appropriate life-saving intervention. Sentinel lymph node biopsy should be considered in patients with high-risk SCC.