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
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
- 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
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.
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.