Which Squamous Cell Carcinomas Are the Bad Actors?

Squamous cell carcinoma (SCC) is seen daily in most dermatologists’ offices. Most are taken care of, never to be heard from again, but, occasionally, an SCC will recur or metastasize. In this prospective, longitudinal study from Germany, 615 white patients with primary SCC referred to a university dermatology department for definitive treatment were followed for at least 4 years. The tumors were resected using “3D-histology,” which consists of en face examination of the peripheral and deep margins and vertical sections from the center of the specimen with examination of permanent sections. The data were subject to rigorous multivariate analysis.

Metastases developed in 4% of patients. The first metastatic focus was always in the regional draining lymph nodes. The risk for metastasis increased with tumor thickness, location on the ear, horizontal tumor size, and immunosuppression. No metastasis occurred in tumors that were 2.0 mm or thinner; 4% of tumors 2.1 mm to 6.0 mm thick metastasized, as did 16% of tumors thicker than 6.0 mm. Lip lesions and poorly differentiated lesions were not associated with increased risk for metastasis. Local recurrences developed in 3% of patients, all within 6 years. Recurrence developed in 12% of tumors thicker than 6 mm and 24% of tumors with a desmoplastic histologic pattern.