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A new Oxford led university study has shown that the greater the levels of Insulin-like Growth Factor-1 (IGF-1) the greater the chances of developing prostrate cancer. Researchers looked at the data of blood samples of 3700 men with prostrate cancer and 5200 men without it, and found higher levels of IFG-1 in the cancer group. Dr Lesley Walker from Cancer Research UK stated ‘there are no clear data on modifiable risk factors’ and also suggests that this work could be helpful in developing drugs (I assume to lower IGF-1 in the blood stream). 

The theory behind IGF promoting cancer goes like this. Cells get energy by binding IGF-1 to the cells IGF-1 receptors, and this causes available glucose in the bloodstream to be directed to that cell. This glucose is the main energy source of cells. Cancer cells have been shown, compared to normal cells, to have an extremely large number of IGF-1 receptors on their surface, thus gaining far more energy or glucose in order to promote growth. This is because cancer cells grow by ‘fermentation’ or anaerobically and thus require far more energy than normal aerobic cells. It has been shown that when tumors are transplanted into mice that have been genetically engineered not to produce IGF-1 the tumor growth is retarded if not eliminated altogether. Effectively the cancer cells are starved of energy (glucose) that is needed for growth and division. If IGF is then injected into the mice the tumors begin to grow. Thus it seems that IGF-1 is vitally important in providing the large amounts of energy that the cancer cells require. 

In the bloodstream, virtually all insulin-like growth factors are attached to small proteins (binding proteins) that carry them around the blood vessels.  When attached to these binding proteins the IGF’s are too large to pass through the walls of the blood vessels in order to get to the cells where the IGF can be used. At any moment, only a small percentage of IGF is left unbound in the circulation to stimulate the growth of cells (including cancer cells). These binding proteins are another mechanism that the body uses to regulate hormonal signals and growth factors. However, insulin depresses the concentration of these IGF-binding proteins. So after a large carbohydrate meal, plenty of glucose enters into your bloodstream causing insulin levels to rise and results in these binding proteins been taken out of circulation. As a consequence, this increases the amount of unbound IGF that can then go and supply potential cancer cells with much needed energy.  

Perhaps one of the ‘risk factors’ that should be mentioned is diets that are high in carbohydrates, result in elevated levels of insulin, which can then, through its various control mechanisms, promote cancer growth. This may help explain why in diabetics there is a much higher chance of developing cancer. Higher insulin levels result in more unbound IGF which can then go and feed cancer cells. Surly, this would be worth mentioning when you consider that in the UK, where this study is done, prostrate cancer is the second highest cancer to kill men.

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