What Is Lung Cancer?

Lung cancer is an uncontrolled growth of abnormal cells in one or both of the lungs.

The body is made up of different types of cells that normally divide and multiply in an orderly way. These new cells replace older cells. This process of cell birth and renewal occurs constantly in the body. Abnormal cells also periodically normally appear but are removed by natural defense mechanisms.

Cancer, also known as a malignant growth, occurs when:

• When the body's natural defenses, such as certain parts of the immune and other protective systems, cannot stop the uncontrolled cell division, cancer begins.

• These abnormal cells become greater and greater in number, and come together to form a tumor, which is a cellular growth that forms a progressively enlarging mass. Such tumors are benign unless they invade surrounding tissues and organs, in which case they are malignant.

Cancerous tumors grow out of control and can invade, replace, and destroy normal cells near the tumor. In some cases, cancer cells spread (or metastasize) to other areas of the body.

Lung cancer generally takes many years to develop even though damage to the lungs may occur shortly after a person is exposed to cancer-causing substances.

Nice To Know: About The Lungs The air we breathe is taken into the two lungs, situated within the chest. Inside the lungs, oxygen is extracted from the air and carbon dioxide, a waste product from the body, is breathed out. The lungs are cone-shaped and are made up of lobes. The right lung has three lobes and the left lung has two lobes. Inside the lungs are air tubes, called bronchi. The right and left main bronchi come off the main breathing pipe, and then split up into much smaller tubes within each lung. Those, in turn, branch into thousands of very small airways called bronchioles. The chest cavity in which the lungs sit is known as the pleural cavity. The smooth lining that surrounds and protects the lungs, enabling them to smoothly expand and contract as we breathe, is called pleura.

Different Types Of Lung Cancer

There are different types of cells in the lung, of varying size, for the different functions of the lung. This has resulted in the classification of two main types of lung cancer:

• Cancer developing from the cells of neural origin in the lung is known as small-cell lung cancer.

• Other types of cancers in the lung are known as non-small-cell lung cancer.

• Some lung cancers are a mixture of both types.

The different types of lung cancers tend to grow and spread differently and are therefore not treated in the same way.

• Non-small-cell lung cancer is the more common type, accounting for about 80% of lung cancers. It is this more common type of lung cancer that grows and spreads more slowly.

• This less common type of cancer, small-cell cancer, is the type that grows more quickly and has a greater chance of spreading to other parts of the body.

Since the more common non-small cell group of cells in the lung are themselves made up of differing kinds of cells, three distinct types of non-small cell lung cancer are recognized. They are:

• Squamous cell carcinoma, often found in the central part of the lung.

• Adenocarcinoma, often occurring in the outer part of the lung.

• Large cell carcinoma, which can occur anywhere in the lung.

People with adenocarcinoma have a more favorable outlook. However, any non-small cell cancers can begin to grow very rapidly and have an unfavorable prognosis.

In general, the choice of treatment and the chances of recovery from lung cancer following treatment will depend on the biological nature of the tumor, which, in turn, is probably related to:

• How advanced the cancer is at the time of diagnosis

• How healthy the person generally is