Lung Cancer

Lung cancer is the 2nd commonest cancer in the United Kingdom (excluding non-melanoma skin cancer).  In most people it is related to cigarette smoking, although some people do get lung cancer who have never smoked.

Some facts about smoking and lung cancer
 
  • The more you smoke, the more likely you are to get lung cancer  
  • Filtered and low tar cigarettes only reduce the risk slightly  
  • As soon as you stop smoking, your risk of lung cancer starts to go down  
  • Fifteen years after you have stopped smoking, your risk of getting lung cancer is down to that of a non-smoker  
  • Passive smoking (breathing other people's cigarette smoke) does increase the risk of lung cancer, but it is still much less than if you smoke yourself

It is almost impossible to work out the risk of passive smoking to non-smokers.  We do know that the risk to passive smokers goes up the more cigarette smoke they are exposed to.  In other words, if you live with a 20+ a day smoker, your risk is higher than if you live with someone who smokes less than 20 a day.

Cigarette smoking is the main cause of lung cancer. But pipe and cigar smokers are still much more likely to get lung cancer than non-smokers. (They are also much more likely to get cancer of the mouth or lip.)

In the past lung cancer has always been more common in men than women. Now, as more women smoke, it is almost as common in women.

There are some other risk factors of lung cancer, but they are nowhere near as important a cause as smoking

  • Exposure to some chemicals  
  • Exposure to asbestos  
  • Exposure to radon gas 
  • Scarring from previous lung disease eg TB 
  • Family history of lung cancer
  • Past cancer treatment

Asbestos has been known to increase the risk of getting lung cancer for some time.  Uranium, chromium and nickel can all cause lung cancer, but this is very rare.

Radon gas is a naturally occurring radioactive gas that can seep out of the soil into buildings. This is more likely in certain parts of the country where there is a lot of granite. It is thought that radon gas in very high concentrations may cause lung cancer.

Air pollution may cause lung cancer, but this has not been proved.

Past lung disease that caused scarring in the lungs may be a risk factor for a type of lung cancer called adenocarcinoma of the lung.  Tuberculosis (TB) can cause scar tissue to form in the lungs.  But a direct link hasn't so far been proved. 


The symptoms of lung cancer can be :

  • Having a cough most of the time  
  • A change in a cough you have had for a long time  
  • Being short of breath  
  • Coughing up phlegm (sputum) with signs of blood in it  
  • An ache or pain when breathing or coughing  
  • Loss of appetite  
  • Fatigue  
  • Losing weight

Less common symptoms
There are other symptoms of lung cancer that are less common.  They are usually associated with more advanced lung cancer.  You may have :

  • A hoarse voice  
  • Difficulty swallowing  
  • Swelling of the face caused by a blockage of a main blood vessel from the head (SVCO)  
  • Swelling in the neck caused by enlarged lymph nodes  
  • Pain or discomfort under your ribs on your right side (from the liver)  
  • Shortness of breath caused by fluid around the lungs (called pleural effusion)


SVCO stands for superior vena cava obstruction.  The vena cava is a large vein that carries blood from the brain and head back to the heart.  If it is blocked, there is a build up behind the blockage causing fluid to seep out from the bloodstream and collect in the tissues of the face, causing swelling.

All of these symptoms can be caused by other diseases apart from lung cancer. So, you should always see your doctor if you are worried about any symptoms. You may have a chest infection, or other illness that is easily treatable. If you do have lung cancer, the earlier it is diagnosed, the easier it is to treat it.
 

Pancoast tumours
Doctors sometimes call lung cancer that is growing right at the top of the lung a 'pancoast tumour'.  These tumours can cause very specific symptoms.  The most common is severe shoulder pain.  They can also cause a collection of symptoms called 'Horner's syndrome'.  These are:

  • Drooping or weakness of one eyelid
  • Small pupil in that eye
  • Loss of sweating on that same side of the face

These symptoms of Horner's syndrome are caused by the tumour pressing on or damaging a nerve that runs up from the neck to that side of the face. 

Odd symptoms
Sometimes lung cancer cells produce hormones that get into the bloodstream. These hormones can produce strange symptoms that you may not realise are anything to do with lung cancer.  You may hear your doctor call these 'paraneoplastic symptoms' or say you have 'paraneoplastic syndrome'.  These hormone related symptoms include:

  • Pins and needles or numbness in fingers or toes 
  • Muscle weakness  
  • Drowsiness, weakness, dizziness or confusion  
  • Breast swelling in men 
  • Tendency to have blood clots (thrombosis) 

These symptoms are rarely caused by lung cancer. But they can be. So it is important you tell your doctor about any new symptoms you have noticed. They may be nothing to do with your cancer and so your mind can be put at rest. If they are, then they can treat them and help you to feel better.

 TYPES OF LUNG CANCER

There are important differences between lung cancer that started in the lungs and lung cancer that has spread to the lung.  This section is about primary lung cancer - cancer that started in the lungs. There are several different types of primary lung cancer. These are divided into two main types:
  • Small cell lung cancer  
  • Non-small cell lung cancer

There is another rare type of cancer called mesothelioma that affects the covering of the lung (the pleura).  It is often caused by exposure to asbestos. It is very different to lung cancer.   
 

Small cell lung cancer
Small cell lung cancer is so called because the cancer cells are small cells that are mostly filled with the nucleus (the control centre of cells).  Small cell lung cancer often spreads quite early on. 

Non-small cell lung cancer
There are four types of non-small cell lung cancer. These are grouped together because they behave in a similar way and respond to treatment differently to small cell lung cancer. The four types are:

  • Squamous cell carcinoma  
  • Adenocarcinoma  
  • Large cell carcinoma
  • Epidermoid carcinoma

Occasionally it is not possible to work out which type of non small cell lung cancer you have. If the cells in the biopsy are very undeveloped, it just may not be possible to tell.

Squamous cell cancer is the commonest type of lung cancer. It develops from the cells that line the airways.  The incidence of squamous cell cancer is going down in the UK.

Adenocarcinoma also develops from the cells that line the airways. But it develops from a particular type of cell that produces mucus (phlegm).  The incidence of adenocarcinoma is increasing and it may soon become more common in the UK than squamous cell lung cancer. 

Large cell lung cancer is called this because the cells look large and rounded when they are looked at under a microscope.

Epidermoid carcinomas are most common among men and the elderly. It starts in one of the larger breathing tubes and usually does not grow or spread as quickly as other types of lung cancer.

How does epidermoid carcinoma develop?
Non-small cell lung cancer is usually associated with a history of smoking, passive smoking or radon exposure. More than 87 percent of lung cancers are caused directly by smoking, while some of the remainder is caused by environmental exposure to tobacco smoke. Other risk factors for lung cancer include a family or personal history of lung cancer and exposure to cancer-causing agents in the workplace or the environment. Asbestos workers are about seven times more likely to die of lung cancer compared to the general population. Exposure to asbestos fibres is an important risk factor for lung cancer. Asbestos workers who smoke have a 50 to 90 times greater chance of getting lung cancer than that of the population in general. Radon, a radioactive gas that occurs when uranium breaks down naturally, cannot be seen, tasted, or smelled. It can become more concentrated indoors and may pose a cancer risk. Studies from populated areas in parts of the United States built over soil with natural uranium deposits have found that the risk of lung cancer may be doubled or even tripled after one has lived in a radon-contaminated residence for an extended period of time. However, when compared to the lung cancer risk associated with tobacco, the radon risk cited in the example above is very small.

What are the symptoms of epidermoid carcinoma?
Although some cancers do not have any symptoms at first, this type of cancer is diagnosed because of complaints such as a persistent cough, coughing up of blood, shortness of breath or wheezing, unexplained weight loss or loss of appetite, fatigue, difficulty swallowing, pain in the chest, shoulder or arm, recurrent pneumonia in the same place, bone pain, hoarseness, headaches, confusion or seizures and swelling of the face, neck or upper extremities.
 

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Cancer that has spread to the lungs
Secondary cancer is cancer that has spread from somewhere else in the body.  There are quite a few different cancers that can spread to the lungs, including breast cancer and bowel cancer. 

It is important to know what you are dealing with so that you can find the right information.  The choice of cancer treatment depends on where the cancer started.  When cancer spreads to the lung from the breast, the cells are breast cancer cells, not lung cancer cells.  So they respond to breast cancer treatments.   And cancer that has spread from the bowel should respond to bowel cancer treatments.

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