The occurrence of lung cancer in women more than doubled between the early 1970s and the early 1990s. During the same period, the death rate for lung cancer in women almost tripled.

The bottom line? Lung cancer surpasses breast cancer as the most common cause of cancer death among women.

Smoking causes more than 80 percent of lung cancer cases in women, according to the American Cancer Society. Cigarette smoke contains more than 4,000 chemicals, 69 of which are known to cause cancer. Some of the chemicals smokers inhale include ammonia (used to clean toilets), cyanide (used to kill rats), formaldehyde (a disinfectant used to preserve tissue and organ samples) and acetylene (the fuel used in torches). Cigarette smoke also contains the poisonous gases nitrogen oxide and carbon monoxide.

Given that information, it isn‘t hard to imagine that inhaling cigarette smoke would damage the lungs, which bring oxygen into the body and take out carbon dioxide (a waste product of the body‘s cells). Irritants in cigarette smoke damage the microscopic hairs (called cilia) that remove unwanted substances from the lungs. They also upset the normal balance of enzymes in the lungs, making smokers more vulnerable to respiratory diseases.

Although almost everyone who develops lung cancer is either a current or former smoker, only about 10 percent of smokers develop lung cancer. Why such a small percentage?

Experts have several theories.

• An individual smoker‘s risk of developing lung cancer may be affected by genetic factors.

• Smokers may die of other causes also related to smoking, most notably heart disease, before lung cancer has a chance to develop.

• Differences in smoking behavior may affect risk. (For example, smoking while drinking alcoholic beverages is thought to further increase cancer risk.)

• Chance. There may be no way to predict which smokers will develop lung cancer. It may be simply a matter of luck.

Lung cancers can be divided into two types: small cell and non-small cell. Cancer cells of each type grow and spread in different ways and are treated differently. Small-cell lung cancers are usually found in current or former smokers. Non-small-cell lung cancers most commonly occur in prior smokers, people who have been exposed to passive smoke or people who have been exposed to radon.

Standard treatments for lung cancer include chemotherapy (using drugs to kill cancer cells), radiation therapy (using high-dose X-rays or other high-energy rays to kill cancer cells and shrink tumors) and surgery (removal of cancerous tissue). Which option is used for a particular lung cancer patient depends on several variables, including the cancer‘s type and stage (whether it has spread to other parts of the body), the tumor size and the patient‘s symptoms and general health.

Most commonly, small-cell lung cancer is treated with chemotherapy, which can kill cancer cells outside the lungs, including cancer cells that have spread to the brain. Radiation may be used to reduce uncomfortable symptoms caused by tumors in the lungs or elsewhere in the body, such as the brain, bones or spine. Patients with non-small-cell lung cancer usually are treated with surgery or radiation therapy. Chemotherapy may be used in some patients. The five-year survival rate for people with lung cancer is about 13 percent. Many factors, such as stage at diagnosis, age and prior health, affect this rate.

For women who smoke, the message is clear: your cigarettes or your health.