Lung Cancer

Lung cancer is one of the most common cancers in the UK with about 38,000 new cases diagnosed each year in the UK. Lung Cancer is difficult to treat and it remains the most common cause of death from cancer in both men and women. The good news is that 90% of lung cancer cases can be prevented by not to smoke or stop smoking.

The Lungs

There are two lungs, one on either side of the chest. Air goes into the lungs via the windpipe (trachea) which divides into a series of branching airways called bronchi. Air goes from the airways into millions of tiny air sacs (alveoli). Oxygen from the air is passed into the bloodstream through the thin walls of the alveoli.

What is Lung cancer?

Normally, our body tightly controls the production of new cells in such way that the number of new ones is similar to the one that dies. Lung cancer develops when certain cells inside the lung escape from body’s control and start dividing and growing in an uncontrolled manner. These abnormal cells, also called cancer cells, gradually form a lump (or a tumour) called primary lung cancer.

Lung cancer may grow locally and damages the tissue around it and/or spread (or metastasises) to the lymph nodes between the two lungs or other organs like liver, bone, brain or bones. Primary lung cancer is different from secondary lung cancer. This is important to know because treatment is different. Secondary lung cancers (or lung metastases) are tumours which have spread to the lung from another cancer somewhere else in the body. This is because all blood flows through the lungs and may contain tumour cells from any other part of the body.

What causes lung cancer? (Risk Factors)

A cancerous tumour starts from one abnormal cell. Cells become abnormal either because they are exposed to harmful factors like smoking or because their genes are altered. Certain risk factors increase the chance of certain cancers forming:


Smoking is a major risk factor and is the main cause of lung cancer. Chemicals in tobacco smoke are carcinogens. Therefore, they can damage cells and lead to cancer developing. Smoking causes about 9 in 10 cases of lung cancer. The risk of lung cancer depends on:

  • the number of smoked cigarettes everyday
  • length of time a person has smoked.

After about fifteen years of stopping smoking, that person’s risk of developing lung cancer is similar to that of a non-smoker.

Other factors

Non-smokers have a low risk of developing lung cancer. However, people who are regularly exposed to other people’s smoke have a small increased risk. People who work with certain substances have an increased risk, especially if they also smoke. These substances include radioactive materials, asbestos, nickel and chromium. People who live in areas where there is a high level of background radiation from radon have a small increased risk. Moreover, Air pollution may be a small risk too.