CASE-CONTROL STUDY OF SQUAMOUS-CELL CANCER OF THE ORAL CAVITY IN DENMARK

A population-based case-control study was designed to examine if the r isk of developing intra-oral squamous-cell carcinoma in Denmark was as sociated with occupation, marital status, residence, dental status, an d exposure to coffee, tea, tobacco, and alcohol. Cases consisted of 16 1 consecutively-admitted incident patients with histologically verifie d, primary, intra-oral squamous-cell carcinoma treated at the Aarhus U niversity Hospital from January 1986 to November 1990. For each case, three controls of the same gender and age were selected randomly from among nonhospitalized residents in the hospital's catchment area (some 1.4 m inhabitants). Four hundred of the selected 483 controls partici pated in the study. Risk was associated significantly with marital sta tus, residence, dental status, alcohol consumption, and exposure to to bacco. When correcting for tobacco and alcohol consumption, only marit al status and dental status remained significant. The association betw een risk and marital status was particularly prominent among divorced compared with married persons (odds ratio [OR] = 2.3, 95 percent confi dence interval [CI] = 1.1-4.6). Persons with less than five teeth had an OR of 2.4 (CI 1.3-4.1) compared with persons with 15 or more teeth. Tobacco and alcohol exposure were the strongest individual risk-indic ators in both lifetime and current consumption estimates, and their co mposite effect was particularly strong. Compared with nonusers, OR for tobacco (> 20 g/d) adjusted for alcohol = 5.8 (CI = 3.1-10.9); OR for alcohol (> 5 drinks/d) adjusted for tobacco = 8.4 (CI = 4.0-17.6). Th e OR for heavy users of tobacco and alcohol (> 20 g tobacco/d and > 5 drinks/d) was 80.7 (CI = 21.8-298.8). These results confirm that tobac co and alcohol contribute significantly to the risk of developing oral cancer. There were no significant differences between the risk estima tes for the two genders or young and old persons. Two simulation studi es indicate that the observed risk associated with tobacco and alcohol consumption cannot be explained reasonably by a high consumption amon g the 83 nonrespondents.