Causes of lung cancer
Cigarette smoking is the most significant cause of lung cancer. Research as far back as the 1950s clearly established this relationship. Cigarette smoke contains more than 4000 chemicals, many of which have been identified as causing cancer.

A person who smokes more than 1 pack of cigarettes per day has a risk of developing lung cancer 20-25 times greater than someone who has never smoked. About 85 per cent of lung cancers occur in a smoker or former smoker.

Passive smoking, or side-stream smoke, presents another risk for lung cancer. A person living with a smoker has twice the risk of lung cancer of someone not regularly exposed to smoke.

Air pollution from motor vehicles, factories, and other sources may increase the risk.

Asbestos exposure increases the risk of lung cancer by 9 times.

Lung diseases such as tuberculosis (TB) and chronic obstructive pulmonary disease (COPD) also create a risk for lung cancer. A person with COPD has a 4-6 times greater risk of lung cancer even when the effect of cigarette smoking is excluded.

Symptoms of lung cancer
One fourth of all people with lung cancer have no symptoms when their cancer is diagnosed while the other three fourths of people develop some symptoms. These cancers are usually identified incidentally when a chest x-ray is done for another reason.

Symptoms of primary lung cancers include cough, coughing up blood, chest pain, and shortness of breath.

A new cough in a smoker or former smoker should raise concern for lung cancer. A cough that does not go away or gets worse over time should be evaluated by the doctors.

Coughing up of blood (hemoptysis) occurs in a significant number of people who have lung cancer. Any amount of coughed-up blood should cause alarm.

Chest pain is a symptom in about one fourth of the people with lung cancer. The pain is dull, aching, and persistent and may involve other structures surrounding your lung.

Shortness of breath usually results from a blockage in part of your lung, collection of fluid around your lung (pleural effusion), or the spread of tumor through the lungs.

Wheezing or hoarseness may signal blockage or inflammation in the lungs that may go along with cancer.

Repeated respiratory infections, such as bronchitis or pneumonia, can be a sign of lung cancer.

When to seek medical care
See the doctor as soon as possible if you develop any of the following:

*Any symptom of lung cancer
*New cough or change in an existing cough
*Hemoptysis - Flecks of blood in your sputum when you cough
*Unexplained weight loss
*Unexplained persistent fatigue
*Unexplained deep aches or pains

Go immediately to the nearest hospital if any of the following occurs:

*Coughing up a large amount of blood
*Sudden shortness of breath
*Sudden weakness
*Sudden vision problems
*Persistent chest pain

Remember that not all abnormalities are cancers, however.

Treatment of lung cancer
The best treatment of lung cancer depends on the type of the tumor or cancer. It also depends on tumor stage. Your general physical condition will also be taken into account. The most widely used therapies for lung cancer are surgery, chemotherapy, and radiation therapy.

Many lung cancers come back within the first 2 years after treatment. You should undergo regular testing so that any recurrence can be identified as early as possible. You should be checked every 3-4 months for the first 2 years and every 6-12 months thereafter.

Prevention
Lung cancer remains a highly preventable disease because 85 per cent of lung cancers occur in smokers or former smokers. The best way to prevent lung cancer is not to smoke.

Cigarette smoking is highly addictive, and quitting often proves to be difficult.