What is lung cancer?
Lung cancer is characterized by an uncontrolled growth of abnormal cells, which arise from the lungs. It is often cells located in the respiratory tract that are the origin of lung cancer. These abnormal cells cannot reverse back to normal and healthy cells, but instead they split up rapidly and thus form tumors of abnormal cells.
As the tumor grows larger, it gradually undermines the ability of the respiratory cells in the lungs to supply the blood with oxygen. Tumors that do not spread from the place of origin are called benign tumors.
A different kind of tumor is called a malignant tumor, which is considerably more severe and more dangerous than benign tumors. The malignant tumors are able to spread to other places in the body and often spread through the blood or lymphatic system. When cancer cells spread from their place of origin, the cancer is more difficult to treat.
There are two forms of lung cancer: primary and secondary lung cancer. The primary lung cancer has its origin in the lung tissue, while secondary lung cancer has its origin elsewhere in the body and from there it has spread to the lung tissue.
Incidence and mortality
Today, cancer is the leading cause of death, in which about every third of deaths are due to cancer. The deadliest form of cancer in the UK for both men and women is lung cancer. Figures from the British Cancer Society shows that about half of those, who have lung cancer, die in the first year after being diagnosed.
One reason that the mortality rate is this high for lung cancer, may be due to the fact that the cancer can be present for several years before any symptoms are seen. During this long period of time, the lung cancer may have spread, which complicates the treatment of the patient.
Why are people developing lung cancer?
The development of cancer is a result of cells growing uncontrollably and without dying. The naturally occurring cells in the body all have the same fate, in which they grow, split up and ultimately die. When normal cells die, it often happens by a mechanism called apoptosis or programmed cell death.
Cancer cells have changed their fate; they have the ability to avoid the programmed cell death, and are therefore able to continue growing and splitting up, whereby the tumors of the cancer cells are formed.
Lung cancer occurs when there is a change in the lung cells’ DNA, which makes it impossible for the cell to restore the damage and to undergo programmed cell death. These changes are also called mutations and can be made on the basis of a long series of incidents. Mutations associated with lung cancer are often a result of the inhalation of carcinogenic substances.
These carcinogenic substances are a group of different substances, which have a direct damaging effect on DNA, and which ultimately increase the incidence of cancer. Tobacco, asbestos and radiation are all members of the class of carcinogens.
In the context of lung cancer, tobacco smoking is of particularly interest, since 87% of the cases of lung cancer are associated with tobacco smoking. Tobacco is of course not the only reason for the development of lung cancer. The reason why smoking is getting so much attention, is because lung cancer can be severely prevented by refraining from smoking and by avoiding exposure to the smoke from cigarettes.