Women and Lung Cancer

When most women think of cancer, they think of breast cancer or ovarian cancer. Increased awareness of these two diseases has led women to seek treatment earlier and has saved lives.

Another cancer, however, deserves the same attention. Over the last 20 years, according to the American Lung Association (ALA), more women have died each year from lung cancer than breast cancer. Before 1987, breast cancer was the leading cause of cancer death in women. The Centers for Disease Control and Prevention ranks lung and bronchus cancers as the second leading cause of death for women, behind heart disease.

When both men and women are included, lung cancer kills more people than colon, breast and prostate cancers combined, making it the leading cause of cancer death, according to the American Cancer Society (ACS). The average age for people diagnosed with lung cancer is 65. It does not usually occur in someone under age 45, but it can, especially in heavy smokers.

Breathing lessons

The two lungs bring air in and out of the body, taking in oxygen when you inhale and getting rid of carbon dioxide when you exhale. The air enters the lungs through the windpipe, or trachea. Once in the lungs, the windpipe divides into tubes called bronchi, which further divide into smaller branches called bronchioles. At the end of the bronchioles are tiny sacs known as alveoli. There, oxygen passes into the bloodstream for use by the body, and carbon dioxide is passed into the alveoli to be exhaled through the lungs.

Most lung cancers start in the lining of the bronchi, according to the ACS. Other sites for lung cancer are the trachea, bronchioles, and alveoli. Lung cancers develop slowly, beginning with precancerous changes. These changes can't be seen on an X-ray (no mass or tumor), and they cause no symptoms. Researchers know about the changes, however, because they have studied cells in the lining of the airways damaged by smoke.

Genetic mutations occur when the genetic material responsible for producing cells is damaged. Tobacco smoke and other carcinogens cause these mutations. Lung cancer is the uncontrolled growth of abnormal cells in the lungs, most often starting in the lining of the bronchi. But it can also start in the trachea, bronchioles, or alveoli. Reproducing quickly, these damaged cells form tumors, which may block air passages in the lungs and prevent their normal functioning. Often, in a process called metastasis, cancer cells break away and spread to other parts of the body.

Lung cancers are divided into two main groups: non-small-cell lung cancers and small cell lung cancers. If a lung cancer has characteristics of both, it is called a mixed small cell/large cell carcinoma.

According to the ACS, about 10 to 15 percent of all lung cancers are small-cell cancers. "Small cell" refers to size and appearance of the cancer cells, says the ACS. It is less common than non-small cell. These cancer cells grow quickly and form large tumors and spread to other organs like the liver, bone, adrenal glands, and brain. These cancers are associated with smoking in most cases.

Non-small cell cancers make up the rest of lung cancers. It is more common than small cell lung cancer, and it generally grows and spreads more slowly. It is further divided into three subgroups:

• Squamous cell carcinoma, the most common type of lung cancer linked to smoking

• Adenocarcinoma, which accounts for about 40 percent of lung cancers

• Large-cell undifferentiated carcinoma, which can spread rapidly

Legacy of smoking

The American Lung Association estimates that smoking is directly responsible for 87 percent of all lung cancer cases in the United States each year. The longer someone smokes and the more cigarettes he or she smokes, the greater the risk.

If you stop smoking before a cancer develops, your damaged lung tissue gradually starts to recover, says the ACS. If you remain smoke-free for 10 years, your risk of developing lung cancer falls to 50 percent of what it would have been had you continued to smoke.

Lung cancer takes many years to develop, and it is difficult to diagnose in its early stages. Unfortunately, not enough lung cancers are found before they have spread. Because lung cancer statistics reflect smoking patterns of the past, there will be some decrease in its occurrence in the near future; smoking rates have declined over the last 30 to 40 years. But the incidence of smoking among teenagers does not bode well for the future.

Other causes

Other risk factors for lung cancer include exposure to secondhand smoke, exposure to asbestos and other workplace carcinogens (chemicals such as arsenic, vinyl chloride, nickel chromates, coal products, mustard gas, and chloromethyl ethers; and fuels such as gasoline and diesel exhaust), perhaps a diet low in fruits and vegetables, genetic predisposition (it seems only with some other environmental agent), and marijuana smoking.