Smoking partially responsible for lung cancer link with lower socioeconomic status

NEW YORK (Reuters Health) - In developed countries, lung cancer incidence and mortality tend to be higher in groups with a lower socioeconomic status. Now, evidence from the European Prospective Investigation into Cancer and Nutrition (EPIC) study suggests that more than half of that disparity is explained by higher smoking rates.

Dr. Gwenn Menvielle, at Hopital Brousse, Villejuif, France, and co-authors evaluated data for close to 400,000 subjects in 10 European countries using educational attainment as a proxie for socioeconomic status. During a mean follow-up of 8.4 years, 939 men and 692 women developed lung cancer.

As expected, lung cancer risk increased as educational level decreased. The relative index of inequality for men was 3.62, and for women, it was 2.39.

"Adjustment for smoking decreased relative educational differences in lung cancer incidence by 50%-70%, most notably in countries where higher lung cancer incidence was observed among people with lower education (men and women in Northern European countries and men in Germany)," the authors report in the Journal of the National Cancer Institute for March 4.

Further adjustment for fruit and vegetable consumption did not significantly alter the estimates.

Dr. Menvielle's group speculates that such factors as radon in homes, occupational and environmental exposures to pollution, differences in physical activity, and ethnicity also may contribute to the residual inequalities in rates of lung cancer.

In a related editorial, Dr. Michael J. Thun at the American Cancer Society in Atlanta comments that in the early 20th century, there was no association between low socioeconomic status and risk of lung cancer. The disparity only became evident in the 1970s, following trends in the dissemination of manufactured cigarettes.

"In the near term and for the foreseeable future," he states, "the most effective approach to reducing both the socioeconomic disparities and the overall burden of lung cancer is to implement measures that we already know are effective in reducing tobacco use."

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