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Suspicions have recently arisen that cancer of the lip may exert an undue influence on overall oral cancer statistics and, therefore, possibly distort the true image of intraoral cancer. The authors investigated this question through epidemiologic analysis. A total of 2291 cases of lip cancer accessioned by the Connecticut Tumor Registry (CTR) from 1935 to 1985 (23.6% of all oral cancer) were analyzed. Occurrence trends for males and females had different patterns: for men, the age-adjusted incidence rates showed a fivefold decrease during the 51-year study; for women, the rates were relatively low and constant during the same period. Analysis for age-specific rates revealed that the older the age group, the higher the incidence rates for both sexes. Squamous cell carcinoma accounted for at least 87.4% of all lip cancers (96.2% if nonspecified epithelial neoplasms are assumed to be squamous cell carcinoma). The vermilion border of lower lip was the most common site. Moderately differentiated tumors were most common 48.5%), closely followed by well-differentiated tumors (44.2%). Analysis by county showed that the crude incidence rates for males in New London and Windham counties exceeded the average Connecticut statewide rates. The authors concluded that the epidemiology of Connecticut lip cancer differs significantly from that of intraoral squamous cell carcinoma in the same population studied within the same period of time. Epidemiologic studies involving 'oral cancer' should direct attention to anatomic subsite to consider differences in disease trends according to specific location. Cancer 1992; 70:2025-2030.

The Connecticut State Tumor Registry recorded 6,181 cases of squamous cell carcinoma of the oral cavity between 1935 and 1985. The age-adjusted incidence rate rose for both men and women during this period. While the rate for men is higher, the rate for women increased more rapidly, and thus the ratio of men to women with this cancer has decreased. In the period from 1980 to 1985, intraoral squamous cell carcinoma had an incidence of 8.5 cases per 100,000 men and 3.3 cases per 100,000 women. Cancer of the oral cavity accounts for between 2 and 4 percent of all cancers in the United States, and about 2 percent of all cancer deaths among men and about 1 percent of all cancer deaths among women. It is well recognized that 90 percent of cancers within the oral cavity are squamous cell carcinomas. In the present study, the tongue was found to be the most common location of the cancer, with the floor of the mouth next most common. These results, which confirm previous reports, are consistent with the role of tobacco consumption as a major risk factor. The floor of the mouth is thought to be susceptible because it represents a collecting pool for saliva laden with cancer-causing substances. The over six-fold increase in intraoral squamous cell carcinoma among women is also consistent with tobacco use as a major risk factor, as the consequences of increased tobacco use among women, which began in the 1920s and 1930s, are taking effect. The peak incidence of intraoral squamous cell carcinoma occurs in the seventh decade of life. While tobacco and alcohol are statistically associated with increased incidence of oral cancer, further studies will be necessary to confirm a causative role. Furthermore, additional study will be required to determine if other, as yet unidentified, causes of intraoral cancer may be contributing to the increases observed in the present study. (Consumer Summary produced by Reliance Medical Information, Inc.)

From 1935 to 1985 the Connecticut Tumor Registry recorded 9,708 cases of oral cancer. These cases were reviewed to determine long-term trends occurring over this period of time. A major trend is the decrease in incidence for men and an increase for women. The incidence among men has fallen from a peak of 14.8 per 100,000 in the early 1960s, to 10.9 per 100,000 in the early 1980s. Conversely, the incidence among women has risen from 1.4 per 100,000 in 1935, to 4.1 per 100,000 in the early 1980s. Although the increase in the incidence of oral cancer among females may be partially attributable to increased smoking among women, this does not seem to account for such a large change. At the current rate of change, oral cancer will be equally common among men and women by the mid-1990s. The study also found that the incidence of oral cancer was roughly proportional to the population density of the area. Thus, city residents are at higher risk than those living in rural areas. (Consumer Summary produced by Reliance Medical Information, Inc.)