Prolonged passive smoking may increase lung cancer risk in women

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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  1. Audrey Silk Audrey Silk United States says:

    I thank News-Medical.Net for printing this.  This has not been carried anywhere else that I know of and it was apparently first published online a month ago.  As usual, the sound of passive smoke studies that do not conclude harm is deafening silence.

  2. Dave Copeland Dave Copeland United Kingdom says:

    No significant difference...may...might...possibly....

    The World Health Organization is fervently anti-smoking; their goal is its complete elimination. In 1975, before any major studies had been conducted on SHS, the WHO recommended that the goal of anti-smoking activists and health organizations should be to lead the public to believe that secondhand smoke is harmful to nonsmokers. The WHO finally conducted a study on the matter in 1998.

    No doubt confident they could "prove it," the study was actually a textbook example of the right way to conduct an epidemiologic study. It was a case control study using a large sample size and was conducted from twelve centers in seven European countries over a period of seven years.

    We can only speculate that the WHO was horrified by their results: that no statistically significant risks exist for nonsmokers who live or work with smokers. In fact, the study's only statistically significant result was that secondhand smoke has a protective effect on children!

    To reiterate, the study was large, its methodology was sound, and it was conducted by an organization full of anti-smokers who had every motivation to "prove" that secondhand smoke was dangerous.

    The results were the opposite of what they must have been hoping for, and they certainly wouldn't help them "to foster an atmosphere where it was perceived that active smokers would injure those around them."

    The WHO tried to bury the study, but it was eventually discovered by the press:

    "...the science fell off the campaign wagon two weeks ago when the definitive study on passive smoking...reported no cancer risk at all. Don't bet that will change the crusaders' mind. The anti-smoking movement, after all, has slipped from a health crusade to a moral one. It is now obvious that antismoking activists have knowingly overstated the risks of secondhand smoke."--the Wall Street Journal

    In response to revelations about their study, the WHO issued a press release titled "Passive Smoking Does Cause Lung Cancer - Do Not Let Them Fool You." Yet, the release had no science to back up its title (which in effect was the exact opposite of what their study showed). The WHO also neglected to mention the study's one statistically significant result--that SHS has a protective effect on children--which you'd think an organization whose goal was to protect health would want everyone to know.

    Tellingly, this WHO study is often offered to legislators as "proof" by anti-smokers, who know that most politicians are unfamiliar with the true meaning of its results!

    The "problem" of being unable to link SHS to lung cancer had to be corrected, however, so the WHO conducted another study. But it was different from the first one: it was a meta-analysis, which are generally considered to be dubious because they allow those performing the study to cherry-pick data to achieve whatever results are desired.

    Such practices are now standard procedure when it comes to secondhand smoke studies. The only way anti-smokers can achieve their stated goal of making smokers seem dangerous to others is by ignoring all overwhelming indications to the contrary.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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