Could Women’s Lungs Be More Vulnerable to Cancer

What’s the leading cancer killer in women?

If you said breast cancer, think again.

It’s true that breast cancer used to kill more women, but starting in 1987, lung cancer moved up to take over that position. It’s now the leading cancer killer for both men and women.

In fact, according to the American Lung Association, lung cancer accounts for over a quarter of all cancer deaths. That number continued to increase between 1999 and 2012, and though it recently leveled off in men, it’s still climbing in women.

What’s going on? And what can women do to protect themselves?

What is Lung Cancer?

When malignant cells start growing uncontrollably in the lungs, the patient is diagnosed with lung cancer. These cells typically form tumors, and make it more difficult for the lungs to carry out their duty of providing oxygen to the body.

Lung cancer can also develop when cancerous cells move from another part of the body to the lungs, where they seed new tumors inside the lung tissue. This form is called “secondary lung cancer.”

What Causes Lung Cancer?

Smoking is by far the most common cause of lung cancer. Smokers breathe in a number of toxic chemicals from cigarettes, and over time, these chemicals can damage DNA, causing mutations that lead to cancerous growths. Several studies have shown that women may be even more vulnerable to cigarette toxins than men (more on that below).

Lung cancer can also occur in women who have never smoked, however. Sometimes the cause is unknown, or it may occur because of exposure to secondhand smoke. A 1991 study, for example, found a 30 percent increased risk of lung cancer in women exposed to environmental tobacco smoke from a spouse. The more the spouse smoked, measured in packs per year, the higher the risk.

Recent studies have also shown a rise in lung cancer in nonsmokers. A 2011 study reported that an estimated 10-15 percent of cases were caused by factors other than smoking in 2008. A 2012 study comparing lung cancer rates between 2000 and 2010 found an increase in the number of women and non-smokers developing the disease. More specifically, nearly 12 percent of cases were in nonsmokers, and nearly 25 percent in women.

“Not only has there been an increase in the number of women and non-smokers contracting the disease,” said lead author Dr. Chrystéle Locher, “but there has also been an increase in the number of cases diagnosed at stage 4 of the illness.”

A 2007 study review also found that American women were more likely than men to have non-smoking-associated lung cancer.

In addition to exposure to secondhand smoke, the following can also be risk factors in non-smokers:

•  Exposure to radon gas, which is the leading cause of lung cancer in non-smokers, according to the Environmental Protection Agency (EPA). Exposure may occur in radon-contaminated homes and buildings.
• Workplace carcinogens like asbestos and diesel exhaust can present a danger to employees. Though this type of exposure has decreased in recent years, the danger is still present in some occupations.
• Air pollution has also been named in recent studies as a potential cause for lung cancer.
• Certain genes may also put women at risk. We know there is a “breast cancer gene.” Though we haven’t found a “lung cancer gene” yet, researchers have found a common gene mutation that’s more common in lung cancer patients who are non-smokers than those who smoke.
• Family history can make some women more vulnerable to the disease. A 1996 study found that lung cancer in a first-degree relative (parent, sibling, child) was associated with a 7.2-fold increased risk of lung cancer among nonsmokers aged 40-59. A more recent 2007 study found similar results—those who had two or more first-degree relatives with any type of cancer had an increased risk of lung cancer.

How is Lung Cancer Different in Women?

As in most areas of research, separating what happens in men from what happens in women is a fairly recent undertaking. It used to be that we thought most health conditions were the same in both genders, but studies over the past few decades have proven this thinking to be incorrect in many cases.

Lung cancer, for instance, seems to develop differently and act differently in women than in men. A 2009 study looked at the issue and found the following:

1. Women may be more vulnerable to carcinogens in cigarettes: Studies have been mixed on this, but some have found that when comparing men and women smokers, women are more likely to develop lung cancer. A 1993 study, for example, found the relative odds ratio for developing lung cancer was 27.9 in women smokers compared to 9.6 for male smokers. Other studies have shown conflicting results, but it could be that women’s lungs are not as resistant to lung cancer as men’s are.
2. Women may be more at risk for cancerous cell changes: Several studies have found that women may be more vulnerable to changes that can occur in cells as a result of being exposed to cigarette smoke.
3. Women may be more vulnerable to growth factors: Certain growth factors in the body can help stimulate cancer cell growth. Studies have found a higher rate of certain growth factors in women smokers than men. Researchers also noted in these studies that females developed lung cancer with significantly less exposure to tobacco than did males.
4. Women may develop lung cancer with lower exposures to cigarette smoke: Several studies have found that women seem to develop lung cancer at lower exposures to cigarette smoke than men. In addition to the study mentioned above, another study found that women with fewer pack-years of smoking and who were younger in age still had higher levels of early cancerous changes in the lungs than men did.
5. Women may not be able to repair DNA as well as men: The body tries to repair any damage cigarette smoke does to the DNA, but some studies have found that women have a lower capacity for repairing DNA than men.

There are some other possibilities. Some studies have found a small increased risk of lung cancer in women taking hormone replacement therapy, suggesting that hormones may play a small part in some cases. Others have found that human papillomavirus (HPV) infection (which can cause cervical cancer) may also increase risk of lung cancer in women.

We need more studies, though, before we can be sure of any of these connections. The one thing that seems to stand out from what we know so far is this: women may be more vulnerable to the negative effects of smoking, secondhand smoke, and environmental toxins than men are.

Women Respond Better to Treatment

Though the study results above are a little scary, the consolation is that so far, research indicates that once women are diagnosed, they typically respond better to treatment than men do—regardless of the severity of their cancer.

A 2003 study, for instance, analyzed records from over 228,000 lung cancer patients and found that survival was better for women for all stages of the disease. Other studies have found similar results. Women typically do well after surgery and radiotherapy, and even have prolonged survival rates with chemotherapy in advanced stages of lung cancer.

How to Protect Yourself—and Watch for Symptoms

Considering all the above, it’s wise for women to watch out for their lungs. Start with the following:

• If you smoke, do everything you can to quit. A 2013 study found that smokers who quit by the age of 40 gained back nine of the ten years life expectancy they lost by smoking in the first place. Those who stopped between 45 and 54 gained back six years, and those who quit between 55 and 64 gained four years.
• Avoid secondhand smoke. Make your home a smoke-free zone, and try to avoid exposure when you’re out and about.
• Check your home for radon gas.
• Follow proper safety procedures at work and ask about any potential exposure to carcinogens.
• Eat a healthy diet full of fruits and veggies—these have healthy antioxidants that can protect your cells against cancerous changes.
• Exercise regularly—it’s one of the best anti-cancer activities you can do!

In addition, be on the lookout for these symptoms:

• A strange cough that doesn’t go away
• A change in your “smoker’s cough” that feels different
• Coughing up blood
• Chest pain and wheezing
• Shortness of breath
• Unexplained fatigue
• Unexplained weight loss