Flow cytometric DNA content analysis of ultraviolet light-induced squamous cell carcinomas: a comparative study of squamous cell carcinomas of the lip and those arising from other sites of sun-damaged skin.

The development of squamous cell carcinoma (SCC) of the lip is considered to be mainly related to excessive sun exposure. However, its higher metastatic rate is distinct from that of SCCs arising from other sites of sun-damaged skin. Flow cytometric DNA content analysis, using paraffin-embedded specimens, was performed on 15 SCCs of the lip and 32 SCCs arising from other sites of sun-damaged skin. A significantly lower incidence of DNA-aneuploidy was observed in SCCs of the lip (2/15) than in those of sun-damaged skin (15/32) (p < 0.05). The mean age of patients with SCC of the lip (66.7 +/- 11.6 years; mean +/- SD) was significantly lower than that of the other patients (78.1 +/- 11.1 years) (p < 0.01). There was no significant difference between the mean diameter size of tumors on the lip (19.5 +/- 5.7 mm) and that of tumors on other sites of sun-damaged skin (30.7 +/- 20.5 mm). These results suggest that additional carcinogenic factors besides ultraviolet light may be involved in the development of SCC of the lip.