The mere mention of it is enough to make most men cringe. But if, as the Institute for Cancer Research warns, prostate cancer overtakes lung cancer as the leading cause of cancer in men within the next three years, many more men will have to submit to the notorious rectal exam in order to save their lives.

Most don't even know were the prostate is located until it starts to cause problems. The organ is about the size of a walnut and is located underneath the bladder in front of the rectum. The gland makes a fluid that is part of semen, which carries sperm.

According to Everyman: Action Against Male Cancer over 21,000 men will be diagnosed with prostate cancer in the UK every year (18,000 according to the NHS). Despite this, there is plenty of good news. The cancer is extremely rare in men under 50 years of age, with 75 per cent of cases occurring in men over the age 65. It also tends to be a slow growing cancer, and as long as it stays contained within the prostate gland, it should be quite treatable. According to Cancerbacup one third of men over the age of 50 have some cancer cells in their prostate, and almost all men over the age of 80 have a small area of prostate cancer. Even so, more men will die with it, than from it, as the University of Pennsylvania in the USA's Cancer Center puts it. Many men will not even realise they have the cancer for many years, since they will not necessarily experience any symptoms.

No-one knows for sure what causes prostate cancer. There is a genetic component for some sufferers - men with a brother or father who developed prostate cancer have a three to five times higher risk of getting it. Two prostate cancer genes have been reported, and, according to Everyman, may be responsible for around 10 per cent of familial cases. Afro-Carribean men tend to develop the cancer slightly earlier. Diet also seems to play a role. While the incidence of prostate cancer in Asia is low, Asians raised in America acquire that country's risk. It seems as if a diet high in animal fats and milk products may increase your risk of developing the cancer, while eating green vegetables may help protect against it.

The rise in the incidence of prostate cancer is probably largely due to the fact that the population as a whole is aging, and many men will now live well beyond 65. More people are also being tested for it, meaning more people are diagnosed. According to the NHS, deaths from lung cancer are decreasing, meaning deaths from prostate cancer will take over as the biggest killer among males.

So why are 10,000 men dying every year of a cancer seemingly so benign? According to the Prostate Cancer Charity, Britain has some of the worst five-year survival rates in Europe. And this is where the bad news comes into play.

The single biggest problem is not that prostate cancer is aggressive, but that there is no single, definitive test for it. Data has to be collected from different tests in order to make a diagnosis. It is also very hard to differentiate between the slow-growing and aggressive forms of prostate cancer, as well as some benign or non-cancerous prostate conditions. To make matters worse, the symptoms of many prostate conditions (including cancer) are unfortunately quite similar [see box].

Prostate cancer can go undetected for years. As the cancer grows, the prostate enlarges, and this squeezes the urethra (urinary tract) which runs through the gland. So the first symptoms of cancer are often problems with urinating. However, men over the age of 50 often suffer from a non-cancerous enlargement of the prostate called benign prostatic hyperplasia (BHP) or hypertrophy, which may cause the same problem. As Cancerbacup points out, most enlargements of the prostate are not cancer.

If you are experiencing symptoms, your doctor will probably suggest two tests. One is a blood test, called the Prostate Specific Antigen (PSA) test. The other is a physical test - the infamous digital rectal examination or DRE.

Unfortunately the PSA test is not a test for cancer. It is a blood test which measures the level of a protein only produced by the prostate gland, and generally speaking, the larger the prostate, the higher the reading. However, many factors, including conditions other than cancer (for example, inflammation of the prostate), vigorous exercise and age can raise a man's PSA level. The PSA test will give the doctor an indication, rather than a diagnosis. If a man's PSA level is raised, the doctor might suggest a DRE.

The DRE requires a doctor to literally feel the prostate gland via a man's rectum. Doctors call the test low-tech; patients probably call it uncomfortable and embarrassing. This test is also not conclusive, because the cancer has to be both present and large enough for the doctor to feel irregularities in the prostate.

There are other tests, such as ultrasound scans, which can be used. Ultimately only a biopsy will provide a definitive diagnosis. And if patients thought the DRE was uncomfortable, a biopsy is done by inserting a lubricated ultrasound probe into a man's rectum and passing a needle through it. This test is uncomfortable and could lead to infection.

Currently the NHS does not screen for prostate cancer as extensively as it does for breast cancer. There is no NHS PSA testing programme. The reason given is that the PSA test is not specific enough, and that there is no conclusive evidence that screening would reduce the death rate for prostate cancer.

This is a very different approach from the one taken in America. In the United States, prostate cancer is also currently the second leading cause of cancer death in men after lung cancer. Just over 30,000 will die of the disease in 2002 - compared to Britain's death rate of over 10,000 per year and the difference in the countries' populations, this seems to be a powerful argument for the testing, at the very least, of at-risk groups.

The American Cancer Society (ACS) recommends that doctors offer the PSA test yearly to men over the age of 50, and to Afro-Caribbean men and others at high risk from the age of 45, although the ACS also notes that the test is not conclusive. According to the ACS, over 80 per cent of prostate cancers are discovered in the local stage (in the USA) and the five-year survival rate for patients at this stage is 100 per cent. The American Society for Clinical Oncology found that America is probably overtesting, and that 98 per cent of men with a very low PSA level at their first test could safely be tested every five years instead of every year.

The NHS and the ACS do agree on one thing: even when cancer is diagnosed, treatment may not be an option. This may sound heretical, but often the side-effects of treatment - among others impotence and incontinence - can be worse than the symptoms of the cancer. The ACS believes men whose life expectancy is less than ten years, due to age or another condition, would probably not benefit from from screening and treatment. Since prostate cancer tends to be slow-growing, they would be more likely to die of something else.

If the cancer is completely contained within the prostate gland, it may not be necessary to receive any treatment. This method of "treatment" is called watchful waiting and regular blood tests and check-ups are used to determine if the cancer is growing. If the cancer starts to grow, it should respond well to more active treatments such as surgery, hormonal therapy or radiotherapy.

If the cancer is growing, but is still completely contained within the prostate, surgery is probably the standard treatment. This requires the removal of the whole prostate gland, which should then get rid of all of the cancer in one go. If the cancer has spread, your doctor will probably recommend chemotherapy, hormonal therapy or radiation therapy or a combination of these. Chemotherapy is the use of medicines or drugs to stop the growth of cancer. Hormonal therapy involves reducing the production of male hormones in the body - since prostate cancer is an exclusively male cancer, the reduction of male hormones slows down the growth of the cancer. Patients may be given a monthly injection, or, in extreme cases, their testicles can be surgically removed. Radiotherapy can be either standard external beam therapy, or via radioactive implants, which can deliver a much higher dose of radiation close to the cancer.

Due to the location of the prostate gland, the nerves which stimulate erections and help with urinary control are easily damaged by all the above-mentioned therapies. As stated earlier, the major disadvantages of these treatments are incontinence and impotence. In many cases these complications are just temporary, but they can be permanent. Even so, post-treatment impotence is treatable. Given these problems patient and doctor should decide together whether treatment is worthwhile.

If men were better informed about their personal risk factors, and generally educated abouth the condition, they would be able to make better choices. Simply being a man and growing older are the greatest risk factors. Being Afro-Caribbean (the death rate for black men is twice as high as white men), having a family history of the disease, and eating a high-fat diet can significantly increase your risk of prostate cancer. Developing a better test for the cancer should also be a priority. In the meantime, even though the NHS does not offer PSA screening test generally, you should ask for one if you are worried.