Nov 18 2014
By Nikki Withers, medwireNews Reporter
Women who have never smoked but are exposed to smoking in the home for more than 30 years are at an increased risk of developing lung cancer compared with women without this passive smoking exposure, suggest researchers.
The analysis also found that women who smoke are 13 times more likely to develop lung cancer than those who have never smoked, but quitting significantly reduces this risk.
The study, published in Annals of Oncology, used data from the Women’s Health Initiative Observational Study cohort to investigate the relationship between active and passive smoking and lung cancer incidence in women.
In all, 76,304 women aged between 50 and 79 years were included in the study. Of these, 6.20% were current smokers and 41.68% were former smokers. Nearly half (47.36%) were nonsmokers but had passive smoking exposure, while 4.77% did not smoke and had no passive smoking exposure.
During a mean follow-up period of 10.5 years, 901 women developed lung cancer, report Heather Wakelee (Stanford University School of Medicine, California, USA) and colleagues.
Current and former smokers were a respective 13.44 and 4.20 times more likely to develop lung cancer than women who had never smoked. This appeared to be dose-dependent; for both current and former smokers the risk of lung cancer increased by a hazard ratio (HR) of 1.58 for each 5 pack–years up to more than 35 pack–years.
When the researchers compared the risk of developing lung cancer between nonsmokers who were exposed to passive smoking and those who were not, they found no significant difference in risk between the two groups.
However, subgroup analysis revealed a borderline significant increased lung cancer risk among nonsmoking women who were exposed to smoking at home for more than 30 years when compared with women with no adult home exposure (HR=1.61).
“Though our results were not statistically significant, our findings suggest that high levels of passive smoking exposure may increase lung cancer risk, with adult home exposure possibly the greatest contributor”, write Wakelee and co-authors.
“Further passive smoking research is warranted, particularly in a prospective cohort setting with pack-years measurement”, the team concludes.
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