Cancer is the name which comprises a group of more than one hundred different diseases, which have in common an uncontrolled cell growth and the dissemination of abnormal cells.
In the normal body cells renew themselves in an orderly manner, enabling the harmonious repair and growth of the tissues of our body.
Cancer occurs when there is a lesion of the genetic material, in other words, of the cell DNA, causing the emergence of mutations. The next step is called «promotion», leading to an uncontrolled proliferation of abnormal cells.
In a healthy person, these cells are eliminated by the immune system. But if our body is unable to recognise and destroy them a malignant neoplasia or a cancer will occur.
Multiple factors can contribute for the emergence of a malignant disease:
- Viral infections
- Excessive exposure to solar radiation
- Exposure to certain chemical agents, hormones and radiations
- Genetic influence
These factors can act separately or in combination during several years until the disease is declared.
In many cases, if we avoid exposure to those factors, we can prevent some types of cancer. That is what happens, for instance, with lung cancer, which is directly related to smoking, and skin cancer related to chronic solar exposure.
Cancer can affect any organ. Nowadays, in Portugal, the most prevalent cancers are, in descending order of frequency, breast, prostate, lung, stomach and bladder cancers.
Most of these tumours have the capacity to infiltrate other organs or tissues and can invade the bloodstream, originating tumours away from original one – metastases -, putting the patients’ lives at risk. For instance, advanced breast cancer may affect the lungs, the liver, the bones, the brain.