Dietary factors and lung cancer among men in west Sweden

Background. Previous studies have reported an association between tea drinking and lung cancer. In view of these data, the relationship between tea drinking as well as other dietary factors and lung cancer was investigated in a case-control study in the west of Sweden. Methods. Patients with suspected lung cancer were collected from pulmonary units at central hospitals in the area investigated, and population controls were matched for age, The material reported here comprises 308 male cases with a confirmed diagnosis of lung cancer and 504 controls. The participants were interviewed by specially trained nurses, using a questionnaire to assess smoking, dietary habits, occupational exposures and conditions in the residential area (local air pollution). This paper reports the results from dietary factors studied with a food frequency technique. Results. The results demonstrated a strong protective effect of vegetables (odds ratio [OR] = 0.69, 95% confidence interval [CI] : 0.46-1.05, and OR = 0.37, 95% CI : 0.23-0.61 for intermediate and high consumption classes respectively), A low OR was consistent for all histological types of lung cancer. High consumption of fruits did not show any similar protective effect. Drinking milk was associated with a dose-response related risk increase after adjustment for smoking and vegetable consumption (P for trend = 0.07). Odds ratio was 1.73, 95% CI : 1.00-3.01 for high consumption of milk. Conclusions. High intake of vegetables had a strong protective effect among males. Diet is thus a potential confounding factor in studies on lung cancer and environmental factors and should thus be taken into consideration in the planning of such studies.