What are the Causes of Cancer
By: Cancer Research UK
Natural Way to Heal Your Cancer. Click Here to Know More.
Weak immune system
Anything that damages the genes in our cells can ultimately cause cancer, but a number of genes in the same cell need to be damaged before a cell becomes cancerous.
The vast majority of cancers are caused by DNA damage that accumulates over a person's lifetime ('sporadic' cancer). Cancers that are directly caused by genetic faults inherited from a parent are rare. For example, for every 20 cases of breast cancer, only one will be caused by an inherited mutation.
Things that can damage DNA include chemicals such as those in cigarette smoke, and radiation like ultraviolet (UV) light. People who have an unhealthy diet also seem to be more likely to develop cancer, although quite how a bad diet is linked to cancer risk is still a mystery. There are even some viruses are linked to cancer.
Carcinogens
Ultraviolet light from the sun can damage your cells and lead to cancer.During the course of a day, we are continually exposed to things that damage our DNA. This damage needs to be repaired by the DNA repair proteins found in each of our cells. Things that damage DNA are called carcinogens, and they include:
* Tobacco
* Car exhaust fumes
* The sun
* Natural and man-made radiation
* Asbestos
Many of these things cause damage because they react with the molecules in our cells to form free radicals. Free radicals are highly damaging molecules, and can wreak havoc on the sensitive machinery inside a cell. Cancer Research UK is funding research into understanding exactly how these carcinogens damage or DNA.
Lifestyle issues
But it is a mistake to believe that exposure to carcinogens is the only cause of cancer. In almost all cases, carcinogens are contributing factors, but there is a whole host of other factors at work. For example, tobacco smoke is a powerful carcinogen, but not all smokers get lung cancer, and some people with lung cancer have not been exposed to tobacco smoke.
Eating a diet high in processed meat can increase your risk of bowel cancer.Although our bodies are continually exposed to carcinogens, there are many things we can do to try to minimise our chances of cancer.
Obviously, giving up smoking will dramatically reduce our chances of developing many cancers. So will limiting our exposure to strong sunlight by, for example, staying in the shade, wearing sensible clothes and high-factor suncream.
But there are other things we can do too.There is a large amount of evidence to suggest that eating a healthy, balanced diet reduces our risk of cancer. We don't fully understand what factors in the diet are responsible for this, but we are helping to fund a massive research project (EPIC) to understand why.
Inheritance and familial cancer
Doctors recommend that we eat at least five portions of fresh fruit and vegetables every day, eat plenty of fibre and starch, and avoid excessive alcohol, fatty foods and red and processed meat.
Some studies indicate that regular physical activity can also protect us against some types of cancer. For example, lack of exercise has been shown to increase a person's likelihood of colorectal (bowel) cancer, whereas maintaining a healthy bodyweight reduces post-menopausal women's' risk of breast cancer.
There is a much more detailed information about lifestyle and cancer risk in the ’Healthy living’ section of this website.
Some people are born with a fault in one of their genes. This does not mean that they will ever actually develop cancer, but it does mean that fewer other things need to go wrong with the rest of their DNA for disease to develop. Doctors say that these people are statistically more likely to get cancer, and that they have a genetic predisposition to the disease.
Other risk factors
For example, women who are born with a mutation in one of their BRCA genes have a much greater chance of developing breast and ovarian cancer than women who do not. If there is a strong history of these cancers on one side of a woman's family, it is possible to have a genetic test to determine if she is a carrier of the gene.
People who are carriers of mutations in one of their BRCA genes can be offered extra screening to pick up any breast tumours early, before they become difficult to treat. Such tests are always carried out with total confidentiality.
People who suffer from certain inherited genetic conditions, such as Familial Adenomatous Polyposis, are much more likely to develop certain types of cancer compared to other people.
You can find out more about the chances of getting cancer in the 'Understanding risk' section of 'Cancer and research'.
There are many other factors that affect a person's chances of developing cancer. The most important ones are listed below. Age
Your risk of developing cancer increases as you get older.Age is an important risk factor for cancer. This is because the longer we live, the greater the number of potentially cancer-causing mutations in our DNA. This is why the disease is so much more common in older people - nearly two-thirds of all cases of cancer diagnosed in the UK occur in people over 65 years old.
Viruses
An electron microscope image of viruses (small black circles) replicating inside a cell (large white area).Some viruses are linked to certain types of cancer. This does not mean that these cancers spread from person to person like an infection, and does not mean that everyone infected with these viruses will develop cancer.
The following viruses are linked to cancer:
* the Human papilloma virus (HPV) is the major cause of cervical cancer
* the Hepatitis B and C viruses can cause primary liver cancer
* the Human T-cell leukaemia virus can cause leukaemia
* the Epstein-Barr virus (EBV) can occasionally cause some types of childhood cancers, carcinomas and lymphomas. Exactly how it does this, and under which circumstances, is not well understood.
* the Human immunodeficiency virus is linked to several cancers as it weakens the immune system (see below)
People who have problems with their immune system are at higher risk of developing cancer, probably because they are less able to combat infections by viruses that are linked to cancer (see above). This group includes people who:
Thanks to CancerReasearch UK: http://www.info.cancerresearchuk.org/cancerandresearch/learnaboutcancer/whatcausescancer
* have had an organ transplant and are taking drugs to suppress their immune system
* have HIV/AIDS
* are born with one of several rare genetic diseases that affect the immune system.
