Demography of Cancer of the Lung

Abstract

This study is based upon 4,129 patients who consulted the author for respiratory disease. All these patients were over 35 years of age. From frequency of cancer of the lung among patients seen in our office, among patients of the General Hospital of Mexico City and from data of other surveys of different groups we infer that this disease is rare in Mexico compared with other countries. In Mexico lung cancer tends to be equally distributed between men and women. This is interpreted as indicating that the epidermoid type is less frequent among men, while adenocarcinoma maintains a constant rate among women. However Mexican women have a slightly higher proportion of epidermoid cancer than might be expected. In Mexico cancer of the lung is more prevalent among Whites who immigrated after they were 35 years of age and who have resided in the country for over 20 years than among native-born Mexicans. Among the author's patients complaining of respiratory ailments, lung cancer was found 50 per 1000 persons in immigrants over 35 years of age who had lived in Mexico over 20 years; the frequency in a comparable group of native-born Mexicans over 35 years of age is 32:1000. Full-blooded Indians rarely suffer from lung cancer; of our 148 cancer patients only three were Indians. The ratio of men to women who suffered from lung cancer was: for immigrants, 3.5:1.0; for native Mexicans 2.3:1.0. The relatively low ratio may have to do with the infrequency of pulmonary cancer in Mexico. The female incidence remains about the same all over the world; the male incidence varies. To this general rule, the frequency of cancer among Mexican women immigrants to Los Angeles forms an exception. The ratio of smokers to nonsmokers in the immigrant group is: for male Spaniards, 1:1.3; for male Jews, 1:1.7. The ratio for Mexican-born males is 1:4.8. The ratio for all women is 1.0:14.8, for Jewish women, 1:5.5. Lung cancer is more frequent among adult immigrants to New Zealand, Israel, Mexico and the City of Los Angeles than among native residents of these places. Lung cancer is much less frequent in Mexico than in the United States or in Europe, according to our estimate, about eight times less frequent. Nevertheless, Mexican incidence is increasing. Certified deaths in 1945 numbered 0.90 per 100,000 and in 1954, 1.7 per 100,000. Causes of variations in incidence may lie in varying amounts of carcinogens contained in the air and in food; a virus of multiple viruses may be another adjuvant factor. Until a determining factor is found, prevention of cancer of the lung must lie in control and avoidance of known carcinogenic factors.