Causes for Prostate Cancer

[lenihant]

I reading about prostate cancer, I get the impression there are two kinds of prostate cancer – one that is aggressive (fast spreading) and one that is slow (you will probably die of something else before it becomes a serious issue!). Can you please help me with the following questions?

1. I haven’t read anything that really explains the cause of prostate cancer except some cells become defective and spread. Is there a better theory?

2. I know that age, racial group, … etc. can have an effect on the probability of getting the disease. But are there any life style contributors?

3. Are there really two types of prostate cancer or are they the same disease in slightly different defective states? If the same, has anyone measured the rate at which the less aggressive group evolves into the other?

[professoreden]

Many prostate cancers are very slow growing and have a low potential to spread to metastasise. We know this from post mortem studies that show that 75% of men aged 80 or more have prostate cancer and that in most of these men there is no evidence of spread. At the other end of the spectrum, we know that 10,000 men die of prostate cancer each year in the UK, so it can be a lethal disease. These extremes of behaviour have lead to the notion that prostate cancer is either a pussycat (indolent) or a tiger (aggressive) but in reality a middle ground also exists in which men have clones or types of both cancers. These are the men in whom early diagnosis is important as they have a potentially lethal disease but if it is treated correctly and in time they can be cured.

The origin of any cancer lies with the mutation of a single cell. The immune system usually detects abnormal cells and destroys them and this process may be repeated many times a month. If multiply this cell mutation rate by the number of years that a person is alive you can see why cancer tends to be a disease that usually affects older men and women. There have simply been more mutations in these individuals and therefore more chances for the immune system to fail to eradicate a single, abnormal cell. These abnormal cells don't respond to the normal signals from the body to stop growing after a certain number of divisions. The cells carry on growing and displace/invade other cells and can pick up a blood supply if they spread to other parts of the body through the bloodstream or the lymphatic system. This process describes the development of a cancer and its local and distant spread.

Genetics certainly play a part in the risk of developing a number of cancers, including prostate cancer, as genes dictate bodily functions including those of the immune system. However, these genes are modified by environmental factors. We know this from twin and migration studies that show, for instance, that the risk of prostate cancer is low in the Far East and high in affluent countries but in men who migrate from poorer to more affluent countries the risk rises several fold. Diet (an excess of saturated fat in red meat and dairy products together with a deficiency of fruit and vegetables which contain powerful anti-oxidants) seems to be the strongest factor but exercise and obesity also play a powerful part.