Mcr. Alavanja et al., ATTRIBUTABLE RISK OF LUNG-CANCER IN LIFETIME NONSMOKERS AND LONG-TERMEX-SMOKERS (MISSOURI, UNITED-STATES), CCC. Cancer causes & control, 6(3), 1995, pp. 209-216
A population-based, case-control study of incident lung cancer among w
omen in Missouri (United States) who were lifetime nonsmokers and long
-term ex-smokers was conducted between 1986 and 1992. The study includ
ed 618 lung cancer cases and 1,402 population-based, age matched contr
ols. Information on lung-cancer risk factors was obtained by interview
ing cases, next-of-kin of cases (36 percent and 64 percent of the case
s, respectively) and controls. Year-long radon measurements also were
sought in every dwelling occupied for the previous five to 30 years. P
opulation attributable risks (PAR) for specific risk factors were comp
uted for all subjects, for lifetime nonsmokers, for long-term ex-smoke
rs, by histologic cell type (i.e., adenocarcinoma cf nonadenocarcinoma
) and for direct interviews with case (for living cases) and for next-
of-kin interviews (for dead cases or cases too ill to complete an inte
rview). The mean age at lung cancer diagnosis was 71 years, and nearly
50 percent of the lung cancers were histologically confirmed adenocar
cinomas. Almost 40 percent of all lung cancers among lifetime nonsmoke
rs and almost 50 percent of lung cancers among all subjects could be e
xplained by the risk factors under study. Dietary intake of saturated
fat and nonmalignant lung disease were the two leading identified risk
factors for lung cancer among the lifetime nonsmokers, followed by en
vironmental tobacco smoke, and occupational exposures to known carcino
gens. A small nonsignificant risk was found for study subjects exposed
to median domestic radon concentration of 4 pCi/l (25-year time-weigh
t average). Since only a small fraction of the population is exposed a
t this level, it is estimated that the PAR for domestic radon was less
than two percent in Missouri. The risk for saturated fat intake was s
imilar for lifetime nonsmokers, ex-smokers, adenocarcinoma cases, and
nonadenocarcinoma cases; however, the increased risk was much more pro
nounced for next-of-kin interviews (PAR = 31 percent) than for intervi
ews with the study subjects (PAR = nine percent). A similar pattern of
PAR was identified among ex-smokers but, in this group, the lingering
effect of a history of smoking was also very important. Along with sa
turated fat intake (PAR = 20 percent), the combined effect of previous
active and passive smoking even after 15 years of cessation of active
smoking was responsible for more lung cancer than any other risk fact
or under study (PAR = 59 percent).