Lung cancer

A 2015 study reports that respiratory cancer accounts for about 4 million deaths annually. In developing countries, researchers project an 81- to 100-percent increase in respiratory cancers due to pollution and smoking.

Many Asian countries, especially India, still use coal for cooking. Solid fuel emissions account for 17 percent of lung cancer deaths in men and 22 percent in women.

Respiratory cancers include cancers of the trachea, larynx, bronchus, and lungs.

The main causes are smoking, secondhand smoke, and environmental toxins.

But household pollutions such as fuels and mold

also contribute.

Causes

Smoking causes the majority of lung cancers — both in smokers and in people exposed to secondhand smoke. But lung cancer also occurs in people who never smoked and in those who never had prolonged exposure to secondhand smoke. In these cases, there may be no clear cause of lung cancer.

Symptoms

Lung cancer typically doesn't cause signs and symptoms in its earliest stages.

Signs and symptoms of lung cancer typically occur only when the disease is advanced.

Signs and symptoms of lung cancer may include:

A new cough that doesn't go away
Coughing up blood, even a small amount
Shortness of breath
Chest pain
Hoarseness
Losing weight without trying
Bone pain
Headache

How smoking causes lung cancer

Doctors believe smoking causes lung cancer by damaging the cells that line the lungs. When you inhale cigarette smoke, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately.

At first your body may be able to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.

Types of lung cancer

Doctors divide lung cancer into two major types based on the appearance of lung cancer cells under the microscope.

Your doctor makes treatment decisions based on which major type of lung cancer you have.

The two general types of lung cancer include:

Small cell lung cancer. Small cell lung cancer occurs almost exclusively in heavy smokers and is less common than non-small cell lung cancer.
Non-small cell lung cancer. Non-small cell lung cancer is an umbrella term for several types of lung cancers that behave in a similar way.

Risk factors

A number of factors may increase your risk of lung cancer.

Risk factors for lung cancer include:

Smoking. Your risk of lung cancer increases with the number of cigarettes you smoke each day and the number of years you have smoked. Quitting at any age can significantly lower your risk of developing lung cancer.

Exposure to secondhand smoke. Even if you don't smoke, your risk of lung cancer increases if you're exposed to secondhand smoke.

Exposure to radon gas. Radon is produced by the natural breakdown of uranium in soil, rock and water that eventually becomes part of the air you breathe. Unsafe levels of radon can accumulate in any building, including homes.

Exposure to asbestos and other carcinogens. Workplace exposure to asbestos and other substances known to cause cancer — such as arsenic, chromium and nickel — also can increase your risk of developing lung cancer, especially if you're a smoker.

Family history of lung cancer. People with a parent, sibling or child with lung cancer have an increased risk of the disease.

Lung disease. certain lung disease such as Tuberculosis increase a person's chance of developing lung cancer. The cancer tends to develop in areas of the lung that are scarred from TB.

Pollution. Research has shown a link between lung cancer and exposure to certain air pollutants, such as by-products of the combustion of diesel and other fossil fuels. However, this relationship has not been clearly

Prevention

There's no sure way to prevent lung cancer, but you can reduce your risk if you:

Don't smoke. If you've never smoked, don't start. Talk to your children about not smoking so that they can understand how to avoid this major risk factor for lung cancer. Begin conversations about the dangers of smoking with your children early so that they know how to react to peer pressure.

Stop smoking. Stop smoking now. Quitting reduces your risk of lung cancer, even if you've smoked for years. Talk to your doctor about strategies and stop-smoking aids that can help you quit. Options include nicotine replacement products, medications and support groups.

Avoid secondhand smoke. If you live or work with a smoker, urge him or her to quit. At the very least, ask him or her to smoke outside. Avoid areas where people smoke, such as bars and restaurants, and seek out smoke-free options.

Test your home for radon. Have the radon levels in your home checked, especially if you live in an area where radon is known to be a problem. High radon levels can be remedied to make your home safer.

Avoid carcinogens at work. Take precautions to protect yourself from exposure to toxic chemicals at work. Follow your employer's precautions. For instance, if you're given a face mask for protection, always wear it. Ask your doctor what more you can do to protect yourself at work. Your risk of lung damage from workplace carcinogens increases if you smoke.

Eat a diet full of fruits and vegetables. Choose a healthy diet with a variety of fruits and vegetables. Food sources of vitamins and nutrients are best. Avoid taking large doses of vitamins in pill form, as they may be harmful. For instance, researchers hoping to reduce the risk of lung cancer in heavy smokers gave them beta carotene supplements. Results showed the supplements actually increased the risk of cancer in smokers.