Some observations concerning the demographic and geographic incidence of carcinoma of the lip and buccal cavity.

The geographic and demographic data obtained during the Third National Cancer Survey have provided a perspective on etiologic factors and incidence trends for cancers of low frequency. The incidence of cancer of the lip, oral cavity and skin from this survey was compared to similar studies in 1947 and intra-regional patterns in one area of the Third National Cancer Survey (Dallas-Fort Worth Metropolitan SMSA) were evaluated. The average age-adjusted annual incidence of cancer of the lip in white men in this latter area was 11.5 per 100,000 (based on 1950 population standard), 2-fold greater than that geographic area with the second highest incidence and approximately 3-fold greater than in all the other areas. The incidence in white women was only 8% that seen in white men. Intra-regional differences of similar populations were seen with the incidence in Fort Worth men being 50% greater than in a similar population in Dallas. Incidence trends over the past 2 decades reveal a significant decline in the incidence of oral cavity cancer and a slight decrease in lip cancer. Comparisons of the incidence of lip cancer did not correlate with the incidence of skin cancer nor with geographic latitude in the other survey areas. The studies fail to support the classical implication of actinic radiation as the primary etiologic factor in lip cancer incidence.