An ecological study of diet and lung cancer in the South Pacific

Incidence rates of lung cancer have been markedly lower for Fiji than for other South Pacific countries, despite similar rates of smoking. We conducted population-based surveys in several island nations of the South Pacific (Cook Islands, Fiji, Tahiti and New Caledonia) and used data from Caucasian, Japanese, Hawaiian, Filipino and Chinese controls in a case-control study of lung cancer in Hawaii to investigate the role of diet in explaining differences in lung cancer incidence among 20 ethnic-sex groups. In a stepwise linear regression of lung cancer rates on smoking, diet and other variables, smoking, as expected, explained the majority (61%) of the variability in incidence. However, several dietary components also explained significant portions of the variance. Lutein intake explained 14% and vitamin E intake, cholesterol intake and height explained 5-7% each of the remaining variance in incidence. Associations with lutein and vitamin E were inverse, whereas those with cholesterol and height were direct. Dietary beta-carotene intake was not associated with lung cancer incidence. These ecological data provide evidence for a protective effect of lutein against lung cancer. A protective effect of dietary vitamin E and a risk-enhancing effect of dietary cholesterol are also suggested.