The trends in histological types of lung cancer during 1980-1988, Guangzhou, China.

Five thousand five hundred and forty six cases of all lung cancer patients who died during 1980-1988 in Guangzhou, China were investigated retrospectively with a standardized 31-item questionnaire administered to their next of kin. The data of 1093 lung cancer patients(20%, 1093/5546) who had a histological record was analyzed to investigate the changes in histological types and the possible etiologic causes. The difference between the lung cancer deaths with and without histological record is not significant in age, location (peripheral or central) of tumour and status of occupation (P > 0.05), but the difference in sex is significant (P < 0.01). We analyzed the data of 1093 cases by sex and by 3-year period. There had been a shift in the histology pattern with an increase in the percentage of adenocarcinoma (P = 0.0011) and a decrease in percentage of squamous cell carcinoma (P = 0.0027) in males, inversely, there has been an absolute and a relative decrease of percentage in adenocarcinoma in females (P = 0.0028). The percentage of smokers, age of starting to smoke and type of tobacco smoking were nearly constant in both sexes during the studied periods. The pack-years of smoking decreased in males (P = 0.0396), and seemed increase in females (P = 0.1576, no significance). The analysis of occupation and dietary habits among 5546 cases were performed. The proportion of housewives decreased with time (P < 0.001) while the percentage of chemists in females increased (P < 0.001) with time. The dietary habits are changing with an increase in roast food intake for males (P = 0.0055) and in vegetable intake for males (P < 0.0001), females (P < 0.0001), and for patients with lung squamous cell carcinoma and adenocarcinoma in both sexes (P < 0.001). Perhaps the changes in pack-years of smoking may be responsible for the percentage change of lung cancer histological types observed in our study. The role that changes in dietary habits and status of occupations play in the changing trends of lung cancer histological types in our study need further study.

An epidemiological study of risk factors for lung cancer in Guangzhou, China.

Lung cancer has been on a rapid rise worldwide during the last three or four decades, in part due to modern social habits and unhealthy lifestyles. Although smoking, air pollution, and certain types of occupational exposure have been recognized as the major risk factors for lung cancer, the significance of each of these factors appears to vary with sex, country, and with region within a given country. In the case of nonsmoking females, some risk factors for lung cancer remain to be identified. In the city of Guangzhou, lung cancer is one of the five leading tumors and the rate has been increasing steadily in both males and females since the 1970s. In this report, more than 6000 cases of lung cancer deaths, accumulated over the past 9 years, were analyzed. The severity of air pollution and cigarette smoking were positively correlated with the incidence of lung cancer deaths. Analysis of levels of SO2 and NOx suggests that the major source of indoor air pollution came from cooking. Two studies were performed in order to determine the relative contribution and importance of smoking, indoor air pollution and occupational exposure as risk factors for the rising incidence of lung cancer. The first was a population-based case-control study involving 849 subjects (566 males and 283 females). The second study was based on the data made available by the Third National Census survey, in which the standardized mortality rate (SMR) and population attributable risk (PAR) for lung cancer due to occupational exposure for the population in Guangzhou were analyzed. Results of these two studies show that: in females, indoor air pollution, derived primarily from burning coal, was found to be a highly significant risk factor for lung cancer. In males, however, cigarette smoking and occupational exposure were significantly associated with lung cancer. To further elucidate the contribution of indoor air pollution as a risk factor for lung cancer in nonsmoking females, two additional case-control studies were performed in 1985 and 1986. The 1985 study involved 120 nonsmokers (28 males, 92 females) in which the influence of such lifestyle factors as: personal history of nonmalignant respiratory diseases, fresh vegetable consumption, lifetime occupation and occupational exposure histories, exposure to environmental tobacco smoke (ETS), degree of indoor air pollution, general conditions of home residence, cooking practices and environments, and family history of cancer were first individually assessed and then collectively subjected to multiple conditional regression analysis for evaluation as risk factors for lung cancer. The 1986 study involved 75 cases of never-smoking females in which the aim was to investigate the influence of exposure to spousal smoke as a risk factor for lung cancer. These studies suggest that consumption of fresh vegetables was a "protective" factor for lung cancer in both males and females. In females, indoor air pollution and size of the kitchen were risk factors for lung cancer, whereas ETS exposure, respiratory disease history, family history of cancer, living conditions, use of cooking fuel, and participation in cooking, were not statistically associated with female lung cancer deaths. Occupational exposure was also correlated with the incidence of female lung cancer deaths. In males, chemists had the highest SMR, whereas in females, homemakers had the highest SMR. In males, the most common lung cancer cell type was squamous cell carcinoma, whereas in females adenocarcinoma was the most predominant type. The factors affecting the distribution of histologic lung cancer cell types were also investigated and discussed.