A review of published reports on lung cancer was done to describe its worldwide epidemiological pattern and to elucidate the contribution of smoking and nonsmoking risk factors in its aetiology. Among lung cancer patients, roughly 98% of males worldwide, and 70-90% of European and American females, reported a history of smoking. Asian women had much lower (6-57%) rates of smoking. Mortality rates among female nonsmokers showed about a four-fold difference, being lowest in India and Japan, intermediate in the USA, and highest among the Chinese. There was some indication that incidence rates among nonsmokers may have increased in some societies in this century. The usefulness of histological comparisons among nonsmokers seemed limited since its distribution did not vary by place or ethnicity; about 70% were adenocarcinomas. In Western populations, younger lung cancer patients were more likely to have been smokers, whereas the opposite was true in Asian populations. Thus the epidemiological patterns of lung cancer in Western and non-Western societies are likely to be different, with nonsmoking risk factors being more important among women in general, and Asian women in particular.

This describes a retrospective study in which 88 lung cancer patients and 137 district-matched controls were interviewed concerning the effects of diet on lung cancer risk among Hong Kong Chinese women who never smoked tobacco. Those in the lowest tertile of consuming fresh fruit or fresh fish had statistically significant adjusted relative risks (RRs) of 2.4 and 2.8, respectively. The protective effects of diet, i.e., higher consumption of leafy green vegetables, carrots, tofu, fresh fruit, and fresh fish, were confined mostly to those with adenocarcinoma or large cell tumors. Only fresh fruit was found to positively, and smoked meats to negatively, affect the risk of squamous or small cell tumors. Foods high in vitamin C, retinol, and calcium seemed to exert larger effects. Subjects from larger households were shown to be more frequent consumers of fresh vegetables, fruit, and fish. Because the lifetime weighted household size could be used as a surrogate index of past dietary quality, when it was combined with current dietary intakes of fresh fruit, the RR increased as either factor decreased in a dose-response manner. The adjusted RR was 5.8 at the lowest level. Further testing of the validity of the lifetime weighted household size as an index of past dietary quality is needed.

The interpretation and interpretability of epidemiologic studies of environmental tobacco smoke (ETS) depend largely on the validity of self-reported exposure. To investigate to what extent questionnaires can indicate exposure levels to ETS, an international study was conducted in 13 centers located in 10 countries, and 1,369 nonsmoking women were interviewed. The present paper describes the results of the analysis of self-reported recent exposure to ETS from any source in relation to urinary concentrations of cotinine. Of the total, 19.7 percent of the subjects had nondetectable cotinine levels, the median value was 6 ng/mg, and the cut-point of the highest decile was 24 ng/mg. The proportion of subjects misreporting their active smoking habit was estimated at between 1.9 and 3.4 percent, depending on whether cut-points of 50 or 100 ng/mg creatinine were used. Large and statistically significant differences were observed between centers, with the lowest values in Honolulu, Shanghai, and Chandigarh, and the highest in Trieste, Los Angeles, and Athens. Mean cotinine/creatinine levels showed a clear linear increase from the group of women not exposed either at home or at work, to the group of those exposed both at home and at work. Values were significantly higher for women exposed to ETS from the husband but not at work, than for those exposed at work but not from the husband. The results of linear regression analysis indicated that duration of exposure and number of cigarettes to which the subject reported being exposed were strongly related to urinary cotinine. ETS exposure from the husband was best measured by the number of cigarettes, while exposure at work was more strongly related to duration of exposure. After adjustment of number of cigarettes for volume of indoor places, a similar increase in cotinine (5 ng/mg) was predicted by the exposure to 7.2 cigarettes/8 h/40 m3 from the husband and 17.9 cigarettes/8 h/40 m3 at work. The results indicate that, when appropriately questioned, nonsmoking women can provide a reasonably accurate description of ETS exposure. Assessment of individual exposure to ETS should focus on daily duration and volume of indoor places where exposure occurred.

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