Risk factors in lip cancer: a questionnaire survey.

An analysis was made of potential risk factors of cancer of the lip in Finland. The series comprised 290 lip cancer patients, and the controls were 254 patients with squamous cell carcinoma of the skin of the head and neck, all reported to the Finnish Cancer Registry in 1972-1973. The results obtained in a questionnaire survey (response rate, 75%; 54% of the total series) indicated that the male lip cancer patients had engaged in outdoor work and smoking with significantly greater frequency than had the male controls. Together, these two risk factors posed a markedly increased risk (RR = 15.4). However, when the factors were analyzed separately, each excluding the effect of the other, no significant risk could be noted. The male lip cancer patients had recurrent herpetic infections with significantly greater frequency than did the male controls. No significant differences were apparent with respect to urban or rural residence. It is concluded that tobacco smoking and outdoor work probably act together to induce lip cancer. The mode of interaction between these factors and the etiologic role of herpesvirus are discussed.