Women's Health Matters

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Despite declining smoking rates, women continue to develop lung diseases

By Patricia Nicholson

Lungs might not be the first thing that comes to mind when we think of differences between men and women, but smoking-related lung diseases do affect men and women differently.

Health Canada statistics show that smoking prevalence has declined steadily over the past three decades in both men and women. One would predict a corresponding decline in related illnesses, and that is the pattern seen in men. However, in women, development of chronic obstructive pulmonary disease (COPD) and lung cancer is actually increasing.

“That’s a little paradoxical,” says Dr. Anna Day, a respirologist at Women’s College Hospital. “We expect that when smoking rates decrease that the number of people who have smoking-related lung disease should decrease as well.”

Smoking-related diseases – COPD and lung cancer – are becoming more and more important for women both in terms of morbidity (things that make them unwell) and in terms of mortality (things that kill them).

There are several reasons why smoking may have different effects on women’s lungs than men’s. Some of these reasons are biological and others are sociological.

Different bodies, different habits

From the perspective of biology, some factors that may influence lung disease differences between men and women include the fact that women’s airways are smaller than men’s, as well as the possible influence of hormones on lung damage. Dr. Day notes that women are more susceptible to asthma, which is marked by reactive airways, suggesting that women are susceptible to other types of lung damage as well.

“Women’s airways probably respond differently to the insult of smoking, both in terms of the type of damage and severity of the damage,” Dr. Day says. “You introduce a toxic agent into the airways and women’s airways seem to be more susceptible to developing different kinds of injury and more severe injury.”

From a sociological perspective, women smoke differently than men.

“For example, women have always smoked filtered cigarettes,” Dr. Day says, explaining that filtered cigarettes mean inhaling smaller particles which travel farther down into the airways. “You develop a different kind of injury than if you have larger particles also impacting on your larger airways.”

Women are also more likely to smoke “mild” cigarettes.

“Nobody really understands what ‘mild’ means,” Dr. Day says. “In most cases it means lower tar. But tar is required for nicotine to get into the brain.”

So if mild cigarettes have less tar, one has to smoke more to achieve the same nicotine level. So the type of cigarettes women choose to smoke may actually cause them to smoke more.

Women also tend to smoke avidly. That means that when women smoke half a pack a day, it might be the equivalent of a whole pack because they are more likely to smoke the entire cigarette.

All of these behavioural factors combined – how and what women smoke – may mean that women are exposed to more toxins.

Also, 20 per cent of lung cancers in women occur in women who have never smoked – an anomaly not seen in men.

There is also evidence that it may be more difficult for women to quit smoking. For men, quitting smoking appears to be about overcoming the actual physical addiction, Dr. Day explains. However, for women, there appear to be more psychosocial issues involved, which may include things like presumed weight gain, stress management and depression.

“They need to modify their own lifestyles to a greater degree before they can even get to the physical smoking addiction issues,” Dr. Day says.

However, there is often a window of opportunity for smoking interventions around pregnancy and fertility, when women may be motivated to quit.

“It’s a unique opportunity to intervene in younger people to help them with smoking cessation,” Dr. Day says, adding that smoking interventions are often aimed at people in their 40s and 50s.

Diagnosis and screening

A third factor that may be affecting women with COPD is delayed diagnosis. Dr. Day notes that people still think of COPD as a man’s disease, when in fact more women have COPD than men.

“There still seems to be a lack of appreciation that women do develop COPD, and often at younger ages than we traditionally see in the male model,” says Dr. Day. So when a woman in her early 50s presents with shortness of breath it may be ascribed to other issues such as menopause, lack of exercise or weight gain, rather than COPD. “So they’re not picked up as having disease early enough. And we think one of the reasons we’re seeing more morbidity and mortality is because there’s a delay in diagnosis.”

Screening spirometry – a noninvasive test that provides information about lung function – can help catch conditions like COPD in its earlier stages. Dr. Day recommends that all smokers and former smokers over 40 years old talk to their doctor about spirometry.

Screening for early stage lung cancer has traditionally been more challenging. Lung cancer remains the number one cancer killer, killing more people every year than breast, prostate, colon, kidney and liver cancer combined.

“That’s something that is so unappreciated by everybody – including women,” Dr. Day says. “If you asked a smoking woman at 25 what she’s more likely to die of, she’ll tell you breast cancer. And yet she’s more likely to die of lung cancer.”

The type of lung cancer that has always been most common in women is adenocarcinoma, which starts in the lung tissue, rather than the airways. This is now the predominant lung cancer in men, also.

The Early Lung Cancer Action Project, an international study, found that CT scans could detect early stage lung cancer. The U.S. National Cancer Institute’s study comparing CT scans to chest X-rays for lung cancer screening found that those who were screened using CT scans had a 20 per cent lower five-year mortality rate from lung cancer compared to those screened using chest X-rays.

These study results have opened the door for the creation of new guidelines for lung cancer screening. In the meantime, Women’s College Hospital screens at-risk women in its Gender and Airways Program using both spirometry and CT scanning.

For women in particular, smoking-related lung illness is an ongoing health issue. The combination of biological susceptibility, behavioural patterns of smoking, and differences in screening and diagnosis is contributing to lung disease in women.

“There are huge gender issues in terms of smoking-related disease,” says Dr. Day. “It’s become a huge issue both for morbidity and mortality for women.”


This information is provided by Women’s College Hospital and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: Nov. 15, 2012

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