The body is made up of many types of cells. Normally these cells grow, divide, and produce more cells as needed to keep the body healthy and functioning properly.(Lung Cancer Transmission Works)

Normal cells constantly reproduce themselves throughout a person's life, but they do so in a systematic and controlled manner. Usually normal cell growth occurs, so worn out tissues can be replaced and wounds repaired.

Sometimes, however, this process goes off track and cells start to grow out of control. They form a mass, and this mass is called a tumour. Tumours can be either benign or malignant.

Cancer is an illness in which abnormal cells in organs and tissues in the body grow out of control. These cells grow and increase in prolific numbers over a period of time. Cancer cells invade and destroy the tissue surrounding them. They split away from a malignant tumour and enter the bloodstream or lymphatic system. (These are the tissues and organs that produce, store, and carry white blood cells which fight infection and other diseases).

This process is called metastasis and it is how cancer spreads from the original (primary) tumour to form new (secondary) tumours in other parts of the body.

Benign tumours are not cancerous. They can usually be removed and, in most cases, they don't come back. Cells in benign tumours do not spread to other parts of the body and most significantly, benign tumours are rarely a threat to life.

Lung Cancer-

Most lung cancer starts in the cells lining the main air passages, or bronchi. In their cancerous state, these cells lack cilia which are tiny hair like substances which normally catch and remove foreign particles inhaled into the lungs.

Mucous in the lungs which is usually cleared by bronchial cilia then becomes trapped, blocking air passages and causing respiratory problems.

There are several different types of cancer affecting the lungs; the principal cancers are described below.

The first three types of cancer start in the lining membrane of the airway in the areas more exposed to inhaled pollutants.

-Squamous cell cancer represents the leading number of lung cancers (approximately 40%-45%).

-Small cell cancers account for 15%-20% of all lung cancer. This is because it spreads rapidly from its characteristically central location.

-Large cell undifferentiated cancer is discovered in about 5%-10% of lung cancer cases.

-Adenocarcinoma usually flares up in outlying areas of the lung and accounts for 25%-30% of all lung cancers. This type of cancer can occur in non-smokers.

Bronchioloalvealar cancer arises in even more remote areas of the lung and accounts for fewer than 5% of the total number of cases of lung cancer. Bronchioloalvealar cancer can also occur in non-smokers.

-There are other rare cancers, but they represent a very small percentage (less than 5%) of the total number of cases of lung cancer diagnosed.

Lung cancer accounts for the largest percentage of cancer deaths in the western world and it has been proved many times over that cigarette smoking is directly responsible for most of those cases!

Causes of Lung Cancer-

As cigarette smoking is a major cause of lung cancer nowadays, it is important to appreciate how smoking affects and injures the lungs. This is because smoke inhalation damages the normal cleaning process by which the lung protects itself from injury.

The bronchi which conduct inhaled air to the lung tissues are lined with a single coating of cells on which lies a defensive coating of mucus.

The hair-like cilia on these cells beat in a regular rhythm to advance mucus upwards continually from the lung removing any inhaled particles which may have become trapped in the process.

The competence of this cleaning mechanism is damaged very quickly by smoke inhalation. The cilia disappear and the coating they lie in thickens in an attempt to protect the fine underlying tissues from injury. Once this damage has occurred, the lung can no longer keep itself uncontaminated.

As a result, the cancer-producing agents in cigarette smoke remain ensnared in the mucus on the surface lining of the airway. They then pass into the cells before being removed by coughing which is the only cleansing mechanism remaining.

Once they are within the body, these chemicals, and their by-products, alter the very nature of the cells in the lungs slowly and increasingly until finally cancer develops.

Most lung cancers start in the lining of the bronchi, though some cancers also begin in the trachea, bronchioles, or alveoli.

Lung cancer is thought to develop over a period of years. To start with there is probably areas of pre-cancerous changes in the lung, but these changes don't form a mass or tumour.

Unfortunately they can't be seen on an x-ray and they don't cause any symptoms. As the cancer develops, it continues to grow and forms a tumour which is then large enough to be seen on x-rays.

These pre-cancerous changes can be exposed by analysing cells in the lining of the airways of smoke-damaged lungs. Molecular abnormalities considered to be pre-cancerous have also been recognized in cells from people who are at high risk of developing lung cancer. These pre-cancerous changes usually progress to true cancer.

Copyright 2005 By Gary Martin