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!
Since most lung cancer is diagnosed at a relatively late stage, only 10% of all lung cancer patients are eventually cured.
8 out of 10 lung cancers are due to tobacco smoke.
The American Cancer Society estimates 164,000 new cases of lung cancer are diagnosed yearly in the United States and an approximate 157,000 people die from the disease each year.
Top Image: Nephron CC BY-SA 3.0 or GFDL, via Wikimedia Commons. Micrograph of small cell carinoma of the lung.