Passive smoke exposure can increase lung cancer risk by nearly one third

People exposed to secondhand smoke are 13% to 32% more likely to develop lung cancer than unexposed individuals, according to a report published in the December 10th online issue of the International Journal of Cancer.

The findings are based on an analysis of data from a US study and a European study that included a total of 1263 lung cancer patients who never smoked and 2740 population and hospital control subjects. The analysis focused on smoke exposure from three sources: spousal, workplace, and social settings.Compared with non-exposure, ever exposure to spousal smoking raised the risk of lung cancer by 18%, lead author Dr. Paul Brennan, from the International Agency for Research on Cancer in Lyon, France, and colleagues note. With long-term exposure (at least 31 years), the excess risk was 23%.Ever exposure to smoking in the workplace was associated with a 13% increased risk of lung cancer, the researchers state. Once again, with long-term exposure (at least 21 years), the excess risk was higher, at 25%.Ever exposure to smoking in social settings increased the risk of cancer by 17%. With 20 years or more of exposure, this risk rose to 26%.As expected, the greatest cancer risks were seen in subjects exposed to smoke from multiple sources. For example, people exposed to smoke from all three sources for 39 years or more were 32% more likely to develop lung cancer than nonexposed individuals.Sensitivity analysis revealed that, if anything, the researchers’ figures may underestimate the true risk associated with passive smoke exposure. “Our pooled analysis provides more precise estimates of the effect of secondhand smoke on lung cancer risk in nonsmokers from all sources than those previously obtained in individual studies and emphasizes the importance of protecting nonsmokers from secondhand smoke,” the investigators state.(Source: Int J Cancer 2003;December 10th online issue:000-000: Reuters Health: December 10, 2003: Oncolink)