CARCINOEMBRYONIC ANTIGEN (CEA), SMOKING, AND CANCER IN A LONGITUDINAL POPULATION STUDY

In 1969, the prevalence of raised levels (5 ng/ml of serum) of CEA was estimated in 2372 persons aged 40 yr and over in Busselton, Western Australia. There were raised levels of CEA in 73 subjects (3%). The prevalance increased progressively with age in nonsmokers and smokers, with a higher rate of prevalence at all ages in smokers, and a peak of 11% in smokers aged 65-74 yr. Among non smokers, the prevalence was similar in men and women (1%). In smokers there was a stepwise rise in prevalence with increasing tobacco consumption. Levels of CEA of 5 ng/ml or over disappeared from the sera in a greater proportion of the non/ex-smokers than smokers. In the following 5 yr, CEA associated cancer occurred in 9 of 73 subjects (13%) with raised levels of CEA compared with 25 in 2299 (1%) in those with normal CEA levels. This association was independent of the confounding effects of age, sex and smoking. The 5 yr data on 2372 subjects confirmed that CEA screening of healthy Busselton subjects identified a group at future risk of developing CEA associated cancers, in addition to drawing attention to the presence of existing cancers.