Often, there are areas of pre-cancerous changes in the lung. Many people have the belief that this disease strikes swiftly, but this is rarely the case. It customarily develops over a period of years.



In this stage, these changes don't turn into a tumour or mass, they aren't even visible in an x-ray. This is normally the stage of the tumor that is operable, consequently curable. Unfortunately, because there are commonly no symptoms, it is normally missed.

These pre-cancerous changes normally progress to an aggressive class of cancer. As a tumor develops new blood vessels form to nurture the cancer cells. Ultimately, a tumor develops and grows big enough to see on x-rays. Once it gets to a certain stage, bits from the tumor cut loose and spread out to other areas of the body through the bloodstream or the lymphatic system. This occurrence is called metastasis.

It then has a tenancy to spread to other parts of the body before it's detected on a chest x-ray. This is predominantly why it is a life-threatening disease.

Here are the two major types;

Small Cell Lung Cancer (SCLC),

Non-Small Cell Lung Cancer (NSCLC)

Which type is recognized is reliant on how the cells appear when they are examined. However, there are also other types. Each type grows and spreads in different ways and requires different types of treatments, so it's critical that doctors get it diagnosed right.

In very rare cases, the cells may have characteristics of both types, and in this instance it is called a Mixed Small Cell/Large Cell Carcinoma (MSCLCC).

Around 13% of all lung cancers are Small Cell (SCLC), and these tend to spread widely through the body. Meaning, management for the tumor should incorporate drugs to kill the widespread disease.

Small cell (SCLC) is caused by smoking. It is very unusual for someone who has never smoked to develop small cell (SCLC).

Small Cell (SCLC) cells can replicate rapidly to form large tumors which can then spread to the patient's lymph nodes and other organs in his body such as the adrenal glands, bones, brain and liver. If this happens, the prognosis normally becomes very poor for the patient, and they can die very quickly.

About 87% of all lung cancers are Non-Small Cell (NSCLC), of which there are three main types. These types of NSCLC are characterised by the size, shape, and chemical composition of the cells that form the tumor.

* Adenocarcinoma: This cancer accounts for about 40% of all lung cancers, and is found in the external region of the lung. Individuals with Adenocarcinoma known as Bronchioloalveolar Carcinoma have a tendency to have a better outcome of successful treatment and recovery than those with any other types.

* Squamous Cell Carcinoma: is also known as Epidermoid Carcinoma. It accounts for around 25% - 30% of all lung cancers, and is associated with a history of smoking. This type is almost always found in the central chest area, near the bronchus.

* Large-Cell Undifferentiated Carcinoma: This type of cancer accounts for about 10% - 15% of lung cancers, and may emerge in any part of the lung. This type of tumor tends to grow and spread very quickly, resulting in a poor prognosis for the patient.

Other tumors can also develop in the lungs in addition to the two main types, SCLC and NSCLC.

Carcinoid tumors account for around 5% of lung tumors. Some of these tumors are non-cancerous. Generally carcinoid tumors are slow-growing tumors called Typical Carcinoid tumors. These can be successfully treated with surgery.