Lung cancer is a class of cancer that begins in the lungs. Cancer originates when cells in the body start to multiply enormously. The lungs are a pair of spongy, air-filled organ in the chest region that take in oxygen when a person inhales and release carbon dioxide when exhaling. People who adopt the habit of smoking have the high possibility of developing lung cancer. However, individuals who have never smoked can also acquire lung cancer.
Lung cancer usually does not cause any symptoms in its earliest stages. The signs and symptoms of lung cancer typically occur when the disease is advanced stage. These signs and symptoms may include:
Cancer that initially emerges in the lungs is called ‘primary lung cancer’. There are mainly two types of primary lung cancer, which are categorized by the type of cells in which cancer originates. They are:
1. Non-small cell lung cancer – This is the most common type of lung cancer. There are three subtypes of lung cells that are classified under Non-small cell lung cancer. These subtypes are as follows:
2. Small cell lung cancer – This type of lung cancer is rare. It usually tends to grow faster and spreads to other parts of the body as well. Sometimes cancers that started in another body part spread to the lungs. This is known as secondary lung cancer.
The majority of lung cancer is caused by smoking.However, lung cancer also takes place in people who never smoked and in those also who never had prolonged exposure to secondhand smoke. In such cases, there may be no clear cause of lung cancer. According to WHO, lung cancer is the leading cause of death caused by cancer.
Other factors that may increase the risk of lung cancer are:
There are a number of factors that may increase the risk of developing lung cancer. Some of these factors can be controlled, such as quitting smoking. Some factors cannot be controlled, such as family history.
Risk factors associated with lung cancer include:
Smoking: The risk of lung cancer increases as the number of cigarettes and the number of years an individual have been smoking increases. Quitting at any age can remarkably lower the risk.
Exposure to secondhand smoke: Even if a person does not smoke, the risk of lung cancer may increase if someone is exposed to secondhand smoke.
Previous radiation therapy: If an individual has undergone radiation therapy to the chest for another type of cancer, there may be an increased risk of developing lung cancer.
Exposure to radon gas: Radon gas is produced by the natural breakdown of uranium in rock, soil, and water that eventually becomes part of the air we breathe. Unusual levels of radon can accumulate in any building, workplaces, and homes.
Being exposed to asbestos and other carcinogens: Exposure to asbestos and other substances known to cause cancer such as arsenic, chromium, and nickel can increase the risk of lung cancer, especially if a person is a smoker.
Family history of lung cancer: People with close relatives such as parents or siblings with a history of lung cancer have an increased risk of the disease.
Air pollution: In cities and towns, air pollution may appear to raise the risk of lung cancer. Nonetheless, this risk is far less than the risk caused by smoking.
Lung cancer can affect more than just the lungs. Once an individual is found with a tumor within the lung, cancer cells can break off and form new tumors in nearby tissues, enter the lymphatic system or bloodstream, and reach other parts of the body. This process is defined as metastasis. Lung cancer tends to spread to the:
Initially, lung cancer affects only the lungs and respiratory system. Other symptoms may vary depending on where cancer migrates.
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