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Women and LC Deaths Not good news

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May 03. 2006 11:15AM

Deaths from lung cancer increase in women


Tribune Correspondent

It's a sad fact of life that it often seems to take a celebrity patient to get the rest of us to sit up and take notice of certain diseases, especially diseases in which the patient's own behavior has contributed to the risk.

Lung cancer is a case in point. Even though it is by far the deadliest of cancers, when it comes to pink-ribbon-style efforts to raise money for research and public awareness, lung cancer lags behind other cancers.

The lack of advocacy work on behalf of lung cancer patients can be attributed to the stigma of smoking. Because smoking is implicated in more than 85 percent of lung cancer cases, people tend to think smokers have only themselves to blame.

But then how do we come to terms with the death from lung cancer last March of Dana Reeve, the widow of Christopher Reeve, who was a lifelong nonsmoker?

Her death, in particular, raises some questions about lung cancer in women. Should women be concerned about developing the disease? Are women more at risk whether they smoke or not? What are the differences in lung cancer between men and women? We know that nobody deserves lung cancer, but is no one truly immune?

There is a growing interest in understanding differences in the way major diseases affect men and women. Researchers have recognized, for example, that women who have heart attacks may not suffer the crushing pain that men experience, and that women are more prone than men to autoimmune diseases like lupus and multiple sclerosis.

Women and men share the same risk factors for lung cancer, the greatest of which is exposure to tobacco smoke, but there the similarities end. According to Dr. Gary Fromm, a pulmonary critical care specialist at Memorial Hospital in South Bend, even though women have never smoked in the same numbers as men, they account for nearly half of new lung cancer cases, and the gender gap is rapidly closing. In the past 80 years, he says, the rate of lung cancer deaths in men has decreased significantly, while at the same time it has jumped 600 percent among women.

These disparities exist because even though women began smoking later than men, smoking in women increased even after its dangers became known. Many women believe that smoking helps them control their weight, and women have a harder time quitting than men do. And, Fromm adds, now that baby boomers are in their 60s, when most diagnoses are made, we are seeing a fourfold increase in lung cancer cases in women. Predictions are that the numbers won't plateau until 2010. But this is a plateau that we may not be able to remain on for long because tobacco use continues to rise among high school girls.

The gender gap

According to research reported by the National Cancer Institute of the National Institutes of Health, compared with men, women who smoke develop lung cancer earlier and with less smoke exposure. But study results are inconclusive and conflicting about whether women are actually more susceptible to the effects of smoking. A problem with these studies is that it's difficult to factor in the effects of secondhand smoke, or other circumstances such as how deeply a person inhales, or how much of the cigarette is smoked.

What we do know is that lung cancer is not biologically identical in men and women. Dr. Robin Zon, an oncologist with Michiana Hematology and Oncology in South Bend, says that the most common type of lung cancer in women is adenocarcinoma; in men, it is squamous cell carcinoma. Women compose more than two-thirds of nonsmokers with lung cancer, and most of them have adenocarcinoma. Also, women smokers are more likely than men smokers to develop small cell lung cancer, a form of the disease that spreads fast and has the poorest prognosis.

Multiple studies have shown that women who smoke have higher rates of genetic damage in lung tumors than their male counterparts as well as less capacity to repair it. Some of the differences in the development of lung cancer may be the result of genetic or hormonal factors, maybe even a combination of both.

Looking to genetics

The role that genetics plays in the risk for lung cancer will grow as scientists continue to discover genetic factors involved in cancer development. For example, a gene called GRPR, or gastric-releasing peptide receptor, is linked to abnormal growth of lung cells and is much more active in women, both smokers and nonsmokers, than it is in men.

An abnormal version of the epidermal growth factor receptor (EGFR) protein is found in abundance on the surface of lung cancers. These mutations, more common in nonsmokers and in women, cause lung cancer patients with these abnormalities to respond better to the newer, targeted cancer therapies such as Iressa and Tarceva.

In another study comparing smokers who had surgery for lung cancer, women were three times as likely as men to carry a genetic mutation that appears to make tumors more aggressive and that may spur cancer growth in response to hormones, especially estrogen.

Many researchers believe that the female reproductive hormone estrogen, that has well-known links to breast cancer, may fuel cancer cell growth or interact with genes that boost the effects of carcinogens. Very early studies have shown that early menopause, which causes a drop in estrogen levels, has been linked with a lower risk of lung cancer; and a recent study of 500 women with lung cancer in the Journal of Clinical Oncology found that those women who had used postmenopausal hormone replacement therapy had significantly lower survival rates than those who hadn't.

Early detection crucial

Zon says that if lung cancer is caught early and hasn't spread, the first step of treatment is surgery to remove the cancer along with some of the surrounding healthy tissue. But about half of the 170,000 new cases of lung cancer diagnosed each year are not surgical candidates because the cancer has already spread within the chest or to other organs. Many older patients have poor lung function or other conditions that preclude surgery, and even in younger patients, symptoms may not appear until the disease is at a stage where surgery is unlikely to help.

Although lung cancer treatment has not undergone the same kind of treatment revolution that's taken place in managing breast cancer, there are the beginnings of change in the way doctors approach the disease. Chemotherapy is now given after surgery because it's been shown to reduce recurrence by around 10 percent. Targeted therapies such as Iressa and Tarceva are being used earlier and more often in women, especially nonsmokers, because they seem to respond better than men. Another recent therapy is Avastin, which helps stop the growth of blood vessels that feed the cancer, a process called angiogenesis. Avastin combined with standard chemotherapy has been shown to prolong survival in lung cancer patients.

If the good news is that female lung cancer patients tend to survive longer, the bad news is that the overall survival rates are still dismal. The overall five-year survival rate for all types of lung cancer patients is only 15 percent, but it's 50 percent in those who are treated before the cancer spreads outside the lungs.

Early detection is crucial in preventing lung cancer death, but there is no equivalent of mammography or colonoscopy for this early detection. Chest X-rays don't find tiny lung cancers, and the use of computed tomography (CT) as a screening tool hasn't been shown to reduce lung cancer mortality. The National Cancer Institute started a large screening trial in 2005 that compares spiral CT (which rotates around the patient to scan the chest) with standard chest X-rays in both men and women. Until results from that trial are known in 2010, the jury is still out on screening measures for lung cancer.

There are things we can do, however, to reduce our risk for lung cancer. We can keep our homes, cars, work environments, and, indeed, even our communities smoke-free. And because you don't have to be a smoker to develop lung cancer, be aware of the symptoms and see your doctor if they persist.

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