Lung Cancer In Focus

(CBS)  The news that ABC News anchorman Peter Jennings has been diagnosed with lung cancer puts a spotlight on the No. 1 cause of cancer death in the United States.

Jennings spoke about his diagnosis Tuesday. The Early Show medical correspondent Dr. Emily Senay reports on the disease.

More people in the U.S. die of lung cancer than of colon, breast, and prostate cancers combined.

This year, there will be about 172,570 new cases of lung cancer in the United States, and about 163,510 people will die from the disease.

It can start anywhere in the lungs, affect any part of the respiratory system and spread to other parts of the body. There are two types: small cell and non-small cell.

Lung cancer can appear in people without any known risk factors, but most lung cancers are caused by tobacco smoke. Tobacco smoke causes more than 8 in 10 cases of lung cancer. The longer a person has been smoking and the more packs per day smoked, the greater the risk.

If a person stops smoking before lung cancer develops, the lung tissue slowly returns to normal. Stopping smoking at any age lowers the risk of lung cancer. Non-smokers who inhale second-hand smoke also have a higher risk of lung cancer.

There are other known carcinogens that irritate the lungs and contribute to the risk of lung cancer.

Along with smoking, asbestos particles, radon gas, previous radiation treatment to the chest, a history of chest disease, family history of lung cancer and a poor diet low in fruits and vegetables can also raise the risk of lung cancer.

There are also a variety of other airborne chemicals, exhaust fumes and other inhaled substances, which can cause lung cancer. Air pollution may also slightly increase the risk of lung cancer.

Most lung cancers do not cause symptoms in the early stages, but if it's caught early, it's more treatable. Surgery, chemotherapy and radiation are used to treat lung cancer, often in combination, depending on the type and the stage of cancer.

Studies show that chest X-rays and checking spit or phlegm for cancer cells don't find many lung cancers early enough to improve the chances of survival, so lung cancer screening is not usually advised even for people at higher risk.

Studies using C-T scanning have shown some promise in finding early lung cancer in smokers and former smokers, but it's not yet proven that C-T scans can lower the risk of death.