Familial Aggregation of Lung Cancer among Hospital Patients

Abstract

NUMEROUS clinical, statistical, or epidemiologic studies of lung cancer in man reported in recent decades have dealt almost exclusively with the exogenous, or environmental, factors associated with this disease. A number of investigators, however, have speculated that endogenous, or genetic, factors may be of etiological importance (1-8). These speculations can be summarized by four statements of somewhat different perspective and specificity: (a) lung cancer is more likely to develop in those who are genetically prone or susceptible to the disease; (b) development of lung cancer may be influenced by the sex-linked genetic mechanism or constitutional sex differences, particularly with respect to hormonal balance; (c) incidence of lung cancer may be related to the differential constitutional makeup of a population, as caused by the temporal, general improvement in longevity, with respect to disease resistance and susceptibility; and (d) both lung cancer and smoking habits may be determined by a common genotype. It is generally assumed that individuals of susceptible genotype are widely distributed in the population, and those susceptibles who are actually exposed to the carcinogenic agent are more likely to develop the disease than those who are not so exposed. Despite such theoretical interests, few empirical studies of human populations have been reported which indicate the possible importance of the genetic factor in lung cancer. Data indicating the presence of familial aggregation of lung cancer would provide the first-step clue for the existence of such a factor. We have attempted to demonstrate the presence of familial aggregation of lung cancer in two different, but related, studies; one conducted in Buffalo, N.Y., and the other in Baltimore, Md. (9). The major findings of the two studies were similar; however, some differences were noted in certain specific details. Since the method of selection and the characteristics of control subjects were different, and the smoking factor was considered only in the Baltimore study, the results of the two studies, should be analyzed separately and compared. The findings of the Buffalo study are presented here.