Prognostic factors in squamous cell carcinoma of the lower lip.

One hundred eighty-seven squamous cell carcinomas of the lower lip were examined microscopically to identify parameters that might predict metastasis and patient outcome. Excision specimens of 157 nonmetastasizing carcinomas (group I) were compared with specimens from 30 tumors that had metastasized (group II). The following features were recorded: architectural pattern; microscopic thickness (mm); cytologic grade; presence of muscle, nerve, or vessel invasion; inflammatory response; and mitotic rate. The mean thickness was 2.5 mm for group I tumors and 7.5 mm for group II tumors. Seventy-six per cent of the group I tumors were 3 mm thick or less, whereas only one group II lesion (3 per cent) was less than 3 mm thick. Five per cent of the group I neoplasms, compared with 77 per cent of the group II tumors, were at least 6 mm thick. Perineural invasion was seen in 5 per cent of the group I and 41 per cent of the group II lesions. Three per cent of the group I carcinomas had a dispersed pattern, compared with 57 per cent of those in group II. One group I lesion (0.6 per cent) and 37 per cent of the group II tumors were grade 4. Each of these differences was statistically significant (P less than 0.0001). For all lesions studied, metastases had occurred in 60 per cent with perineural invasion, 74 per cent measuring 6 mm or more, 77 per cent with a dispersed pattern, and 92 per cent that were grade 4. These important prognostic variables were best evaluated in the deeper portions of the lesions.