Where is the prostate gland?
The prostate is a chestnut-sized gland that is only present in men. It lies just below the bladder and fits around the urethra like a collar. The urethra is the tube through which urine and semen pass out of the body.

Figure 1: The prostate

What is the prostate?
The prostate is made up of smooth muscle and glandular tissue. It can be divided into three zones:

• the central zone
• the transition zone
• the peripheral zone.

The peripheral zone is located at the back of the prostate, and can be easily felt (palpated) by your doctor via the back passage (rectum). This, by chance, is the very part of the prostate that is most susceptible to both prostate cancer and prostatitis. Indeed, about four-fifths of prostate cancers originally develop in the peripheral zone.

The transition zone lies between the central and peripheral zones and is the area where benign prostatic hyperplasia (BPH) develops and progresses to cause obstruction to urinary flow.

The prostate is part of the male reproductive system and manufactures an important liquefying component of semen. The sperm, which are produced in the testicles, are stored just behind the prostate in the seminal vesicles. Here, and at the time of ejaculation, the sperm are in a gelatinous medium. At orgasm and ejaculation, the prostate and the seminal vesicles contract, and this mixes their respective contents. The fluid in the prostate contains large amounts of a substance known as prostate-specific antigen (PSA), which liquefies the previously gelatinous sperm mixture, allowing the sperm to move freely in search of an ovum to fertilize. These secretions of the prostate also help nourish the sperm and aid fertility.

Figure 2: Seminal vesicles

How the prostate develops
In newborn boys the prostate is about the size of a pea and it grows very slowly until puberty. Then there is a dramatic growth spurt and the prostate can double in size in 6 to 12 months. After that, growth slows, then stops. The prostate stays about the same walnut-size until a man reaches his 40s, when it increases again.

This is because the growth and function of the prostate are ruled by the interaction of various hormones - primarily the male sex hormone, testosterone. In the prostate, testosterone is converted to dihydrotestosterone (DHT), a more active form. DHT is responsible for the growth of the prostate. The conversion of testosterone to DHT is controlled by an enzyme known as 5 alpha reductase. In older men this hormonal regulation tends to break down, and, as a result, the prostate gets bigger.

Testosterone is also responsible for the development and function of the reproductive organs and other male characteristics, such as your voice breaking at puberty.

What can go wrong?
The most common sign that you have started to develop a problem is difficulty in passing urine. This is because changes in the prostate can cause a narrowing of the urethra, the tube inside the penis through which urine passes from the bladder.

• BPH: Non-cancerous enlargement of the prostate The gradual enlargement of the prostate gland in middle-aged men can cause problems by constricting the urethra and interfering with urination. BPH is most common in men over 50. About half of all men will have BPH by the age of 60, rising to eight out of 10 in their 80s.
• Prostate cancer: This is rare before middle age, with very few cases occurring in men under 50. Half of all cases occur in men aged under 75, half in men who are over 75. Overall, the average lifetime risk of getting prostate cancer is about one in 12. Most prostate cancers are slow growing and many can be treated effectively, especially if caught early.
• Prostatitis: Inflammation or infection of the prostate This can affect men at any age of their adult life, but is not a life-threatening condition. Prostatitis can either be bacterial or nonbacterial. As the names suggest, bacterial prostatitis is caused by bacteria, whereas with nonbacterial prostatitis, no bacteria are present. Prostatitis may be acute (i.e. it comes on suddenly and usually lasts only a short time) or chronic (i.e. the symptoms persist or flare-up repeatedly over a period of time).

All three prostate diseases � prostate cancer, BPH and prostatitis � tend to cause a greater impact on a sufferer�s quality of life than is necessary. That the conditions often reach a relatively advanced stage before men seek medical help is the result of men�s laissez faire attitude to lower urinary tract symptoms, embarrassment about discussing this area of their anatomy with their doctor, and their general reluctance to undergo regular health checks.

In fact, prostate diseases eloquently illustrate the �stitch in time� principle. A �window of curability� exists for prostate cancer, but once a man�s PSA level exceeds 20 ng/ml, neither surgery nor radiotherapy is likely to be ultimately successful. With BPH, several studies have confirmed that there is a level of secondary damage to the bladder caused by obstruction at which complete recovery becomes unlikely. And if prostatitis becomes chronic, then repeated and prolonged courses of treatment are often needed.

Men�s attitude towards their health has traditionally been "if it ain�t broke, don�t fix it". This needs to be replaced with "if you look after your body (and particularly your prostate) it tends not to break". Regular prostate checks allow detection of disease at a stage when it generally can be resolved, while preventive strategies may reduce the risks of disease developing in the first place.

Problems with urinating are the most common symptoms of prostate disease. Visit your doctor if you experience one of the following:

• A weak, sometimes intermittent flow of urine
• Difficulty starting to urinate
• A need to urinate frequently
• A need to urinate urgently (that is, you don�t feel able to put it off)
• Having to go to the toilet several times during the night (for a period of time)
• A feeling that your bladder is not completely empty after you have finished urinating
• Pain or burning when passing urine
• Blood in your urine.