Any one cancer is rarely the result of a single factor. More than one cause is often involved. In addition, there are different types of cancer that affect the different cells in the body. What affects one body tissue may not necessarily affect another.

Age

As we get older, the general incidence of most types of cancer increases.  This is because a number of changes need to happen to the genes within a cell before it becomes a cancer cell  and this takes time.

It has been estimated that at least eight genetic changes are required for a cell to override all the internal and external controls regulating its behaviour. These different changes accumulate over a long period and together cause the cell to become cancerous.  Change could happen by accident when the cell is dividing or because of carcinogen damage in the form of tobacco smoke or UV radiation.

Whatever the cause, the resulting damage is then passed on to future daughter cells when the cell divides. The longer we live the more time there is to accumulate more genetic mistakes in our cells until the cell has overridden all the controls and is able to divide continuously.

Genetic make up  is cancer hereditary?
 

There have to be a number of genetic mutations within a cell  some estimate at least eight  before a cell becomes cancerous. In some cases, individuals are born with one of these genetic alterations. Whilst this does not automatically mean that person will develop cancer, the fact that they have already accrued one genetic mutation before they start off life, can increase the odds. This situation is termed a genetic predisposition.

A genetic predisposition to certain specific cancers is found in families where several close relatives on one side (for example a mother, aunt or daughter) develop the same type of cancer at a relatively early age (in their fifties or earlier).

In breast cancer, for example, research has shown that individuals in such a family may have a genetic defect in either the BRCA1 or BRCA 2 gene. This means that women in the family with a mutation in one of these genes will have a higher chance of developing breast cancer than if they did not have the mutation.

Although some breast cancers carry a genetic predisposition, the vast majority do not. Most women with breast cancer do not have a mutation in either the BRCA1 or BRCA2 gene. Less than 5% of all breast cancers are due to these two genes.

In other words, most breast cancer is not caused by a hereditary genetic mutation. This is also true of other cancers where a genetic predisposition has been described  such as colon (large bowel) cancer. The main reason why one person gets cancer and another does not is unknown.

Carcinogens

Carcinogens encourage the development of cancerous cells. They do this by attacking and damaging a cells genes  producing a genetic alteration or mutation that provides the cell with another growth advantage over its neighbouring cells.  Most of the time carcinogens are dismantled within the body before they can do any harm  but not always.

They can come from a variety of sources - some of which we know about. These include foods, our environment (such as UV radiation or tobacco smoke), or even from within our own bodies.

At the same time, compounds known as inhibitors can help to prevent the abnormal cells from growing. These too have many sources, including food. Some vitamins in plant foods are known to be inhibitors. In contrast, dietary fat is known to be a promoter that helps abnormal cells grow.

Diet

It is important to remember that a poor diet has many associated risks, including heart disease, diabetes and hypertension as well as cancer.  It can however add strain to our already overloaded body systems, leaving them open to attack by illness and disease, including cancer.

Information about the role of diet has come from many observational studies around the world, across cultures and geographical divides. It is now thought that up to a third of all cancers in Westernised countries may be related to diet.

Research has shown that a diet high in animal fat and low in fresh fruit and vegetables - in other words the diet of industrialised Western nations - can increase your overall risk of cancer. More specifically, cultures with the highest levels of fat consumption are also the ones with the highest death rates from breast and colon cancer. The lowest rates are in those groups with the lowest consumption of fats.

By contrast, in countries where diets are high in fibre (plant based) there are fewer cases of cancer. The industrialised West primarily bases its diet on animal products. These contain very little fibre and are low in animal fat  - thought to be much more harmful than vegetable fat. Accordingly, these countries have the highest rates of colon cancer.

Viruses

A very few viruses have been found to play a key role in causing certain cancers. These viruses are often found in many people in the normal healthy population, not just in the few that develop cancer. When a virus infects someone, it finds it way to a particular cell and can deliberately interfere with the cells genetic instructions to service its own needs.

03/06/2009