The Genetics of Cancer
One of the most important breakthroughs in cancer research came in the late 1970s when scientists discovered that all types of cancer begin with the genetic material within normal body cells becoming damaged. Every cell contains genetic information in the form of more than 90,000 pairs of genes which work together to control the activities of the cell. A cell can become cancerous when specific genes, such as those that control division, become damaged beyond repair. How and why genes become damaged is still a hot topic for research however it would seem that faulty genes are either inherited or they are caused by carcinogens (cancer-causing agents), for example sunlight and cigarette smoke.
Our body cells are continually exposed to carcinogens however in the majority of cases cancer doesn’t develop. There are a number of reasons why this is so, for example:
Cells can normally repair their own damaged genes so that they continue to function properly. More than one gene has to be damaged in order for cancer to develop.
The body’s immune system can normally kill any cancer cells before they get the chance to multiply and form a tumour.
The Causes of Cancer
Although most cancers appear to be caused by several factors, including genetic/inherited ones, a main environmental cause can often be identified for a particular cancer i.e. smoking cigarettes is commonly associated with lung cancer.
Approximately 35% of stomach cancer and prostate cancer cases are related to diets of unhealthy foods with little or no fresh fruit and vegetables. 30% of lung, breast, colon, cervical and throat cancers are related to tobacco products such as cigarettes and cigars. 10% of skin cancer cases are related to the sun and UV rays. 7% of lymphoma, leukaemia, bone cancer and liver cancer cases are related to viruses such as Epstein Barr, HIV, Hepatitis C etc. Pesticides and chemicals, or occupational factors figure into 4% or mouth, throat, stomach and lymphoma cancer cases. Approx 3% of stomach, colon and liver cancer have been linked to excessive consumption of alchohol.
Aging and Cancer
Cancer is most common among older people, largely because their cells have had more time to accumulate genetic damage, but also because the body’s defences against cancer, particularly the cells and proteins of the immune system, gradually become less efficient with age. In addition a cancer that began earlier in life may not be diagnosed until old age because it can take years for some types of cancer, most noticeably prostate cancer, to grow large enough to produce noticeable symptoms.
Because life expectancy has increased dramatically over the last 50 years it means that cancer is now one of the most common causes of death in the developed world, second only to coronary heart disease.
Cancer treatment today
For over 2000 years, doctors have attempted to cure cancer by surgically removing visible tumours. For some localised cancers radiotherapy is very effective and this treatment is often combined with surgery with the aim of achieving a cure. Treatment with anti-cancer drugs, known as chemotherapy, may be used instead of or in combination with surgery to destroy cancers that have unfortunately already spread around the body.
New therapies for the treatment of cancer that are currently being assessed include inactivating the damaged genes so that they no longer send messages to the cell, and boosting the body’s natural immune system so that it has the ability to destroy any cancerous cells. These therapies are still in the experimental phase however both the American Cancer Society and the National Cancer Institute of the UK, i.e. Cancer Research, are working towards making them viable treatment options for future generation.
About the Author:
By: Andrew Daigle