Lung cancer has been on a rapid rise worldwide during the last three o
r four decades, in part due to modern social habits and unhealthy life
styles. Although smoking, air pollution, and certain types of occupati
onal 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 ide
ntified. In the city of Guangzhou, lung cancer is one of the five lead
ing 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 correl
ated with the incidence of lung cancer deaths. Analysis of levels of S
O2 and NOx suggests that the major source of indoor air pollution came
from cooking. Two studies were performed in order to determine the re
lative contribution and importance of smoking, indoor air pollution an
d occupational exposure as risk factors for the rising incidence of lu
ng cancer. The first was a population-based case-control study involvi
ng 849 subjects (566 males and 283 females). The second study was base
d on the data made available by the Third National Census survey, in w
hich the standardized mortality rate (SMR) and population attributable
risk (PAR) for lung cancer due to occupational exposure for the popul
ation in Guangzhou were analyzed. Results of these two studies show th
at: in females, indoor air pollution, derived primarily from burning c
oal, was found to be a highly significant risk factor for lung cancer.
In males, however, cigarette smoking and occupational exposure were s
ignificantly associated with lung cancer. To further elucidate the con
tribution 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, 9
2 females) in which the influence of such lifestyle factors as: person
al history of nonmalignant respiratory diseases, fresh vegetable consu
mption, lifetime occupation and occupational exposure histories, expos
ure to environmental tobacco smoke (ETS), degree of indoor air polluti
on, general conditions of home residence, cooking practices and enviro
nments, and family history of cancer were first individually assessed
and then collectively subjected to multiple conditional regression ana
lysis for evaluation as risk factors for lung cancer. The 1986 study i
nvolved 75 cases of never-smoking females in which the aim was to inve
stigate the influence of exposure to spousal smoke as a risk factor fo
r lung cancer. These studies suggest that consumption of fresh vegetab
les was a ''protective'' factor for lung cancer in both males and fema
les. In females, indoor air pollution and size of the kitchen were ris
k factors for lung cancer, whereas ETS exposure, respiratory disease h
istory, family history of cancer, living conditions, use of cooking fu
el, and participation in cooking, were not statistically associated wi
th female lung cancer deaths. Occupational exposure was also correlate
d with the incidence of female lung cancer deaths. In males, chemists
had the highest SMR, whereas in females, homemakers had the highest SM
R.In males, the most common lung cancer cell type was squamous cell ca
rcinoma, whereas in females adenocarcinoma was the most predominant ty
pe. The factors affecting the distribution of histologic lung cancer c
ell types were also investigated and discussed.