Risk factors in multiple carcinomas of the lip.

Certain risk factors appear to separate subjects with repeated primary carcinomas of the lip from the general population of patients with carcinoma of the lip. Factors that were found statistically significant in increasing the chance of recurrent carcinoma of the lip include outdoor occupations requiring prolonged exposure to sunlight or the use of tobacco on a regular basis. Significant risk factors of a clinical nature include a positive serologic reaction for syphilis; the presence of leukoplakia, hyperkeratosis, or actinic cheilitis; or the presence of a basal cell or squamous cell carcinoma of the facial skin.