The Complete Book of Men's Health - Part 1: Sexual Health

CANCER OF THE PROSTATE GLAND

Cancer of the prostate gland kills three times as many men as cervical cancer kills women ­ yet there is much less awareness about this common disease.

In the UK, 11,500 new cases are diagnosed every year. In the US it is the commonest diagnosed male malignancy (excluding skin cancers), with 122,000 new cases each year. It is the second most common fatal male tumour and the leading cause of cancer deaths in men over the age of 55.

It is estimated that one in every 11 white American males will develop clinically significant prostate cancer at some stage of their lives. The risk for black males is even higher, with one in every 10 eventually affected.

Autopsy studies show that an astonishing 10­30 per cent of men aged 50­60 years, and 50­70 per cent of men aged 70­80 years, show evidence of prostate cancer when glands are examined under the microscope. Most of these cancers remain silent and are never diagnosed. Their owners die with them, rather than from them.

The incidence of prostate cancer found in autopsies is identical among American, Japanese and Chinese men, but for some reason the cancer is more likely to progress to cause symptoms in Western males. The incidence of recognized disease is 26-fold lower in Chinese men and 10-fold lower among Japanese men. When Japanese men emigrate to the US, their risk of developing clinically significant prostate cancer becomes the same as for American men within two generations. This suggests an environmental factor is involved in converting hidden prostate cancers to clinically significant disease. The most likely culprit is the Western diet.

An Hereditary Disease

Cancer of the prostate gland seems to run in families. If a first-degree relative (father or brother) is affected, a man's risk of developing prostate cancer is almost three times greater than normal. If a second-degree relative (uncle or grandfather) has prostate cancer as well, a man's risk increases to six times that of a male with no affected relatives.

Symptoms of Prostate Cancer

Unfortunately there are usually no symptoms in the early stages of prostate cancer. This is because 90 per cent of tumours arise on the outside of the gland and do not obstruct urinary flow initially. Prostate cancer is slow growing and may take as long as four years to double in size. Sometimes a tumour is picked up early because of coincidental symptoms of benign prostatic hyperplasia (see BPH).

Figure 16: Prostate gland showing BPH plus tumour

At a later stage of the disease, a man might notice symptoms of obstruction similar to those of benign prostatic hyperplasia. If the disease spreads (metastasis) to other parts of the body ­ most commonly to bone ­ symptoms and signs such as the following may develop:

• tiredness

• loss of appetite

• weight loss

• bone pain

• anaemia

• blood in the urine or sperm

• swollen glands.

In the UK, only 15 per cent of treatable prostate cancers are picked up in the early stages, compared to 50 per cent in the US where annual screening methods are practised. Screening can take the form of:

• routine blood tests to measure Prostate Specific Antigen (PSA)

• routine digital rectal examinations

• routine Trans-rectal Ultrasound (TRUS) examination of the prostate gland ­ see below.

Diagnosis

In 90 per cent of cases, a cancer arises in the outer part of the prostate gland where it is felt as a small, hard lump or irregularity during a digital rectal examination. If your doctor does find a lump, try not to worry. In half of all cases referred for urgent investigation, no cancer is found ­ the lump is due to a stone or other benign enlargement. Even if cancer is present, if caught early enough it is often curable.

If cancer is suspected, several blood tests may be performed to check for anaemia and to assess kidney function. Measuring the level of a blood enzyme known as Prostatic Acid Phosphatase (PAP) is useful to indicate whether a prostate tumour has spread to form bone secondary cancers.

Prostate Specific Antigen (PSA) is a protein made only by prostate cells. If the level of PSA in the blood is above 10 ng/ml there is a 60 per cent chance that cancer of the prostate is present.

If the level is moderately raised (between 4 and 10 ng/ml) there is a 20 per cent chance of prostate cancer. This is because other conditions such as benign enlargement or even a digital rectal examination sometimes elevate the level. The only way to distinguish between them is via a biopsy.

If PSA is normal (less than 4 ng/ml) there is only a 2.5 per cent chance that a man has prostate cancer.

Other Tests

Trans-rectal Ultrasound (TRUS)

This involves inserting a lubricated finger-shaped probe into the back passage. Sound waves are passed through the prostate gland and bounce back off tissue planes to form a computer-interpreted image. Tumours often show up as abnormal echoes. Unfortunately, this is not helpful if the cancer has the same echoing qualities as the surrounding normal tissues. A proportion of tumours are therefore missed.

Biopsy

Taking a biopsy is the best way to determine whether a prostate nodule is benign or malignant. A fine needle is used to remove a small sample of tissue from the tumour (under local anaesthetic). If the needle is inserted through the back passage, you may be given antibiotics to prevent infection. Sometimes the needle is guided into the lump using ultrasound. Tissue obtained during the biopsy is then examined under a microscope to look for cancerous cells.

Body Scans

(CAT or MRI) are useful to see how far a tumour has infiltrated surrounding tissues and to check if it has spread into pelvic lymph nodes.

Isotope Bone Scan

As advanced prostate tumours commonly spread to bone, an isotope bone scan is performed once prostate cancer is diagnosed. Bone secondary cancers (secondaries) can also be seen on plain X-rays. Occasionally, the disease is only suspected at a late stage after bone pain or fracture has occurred.

Treatment

Treatment varies from patient to patient and from specialist to specialist. It depends on how advanced the cancer is and whether or not it has spread beyond the prostate gland. Once the disease has spread beyond the gland, treatment is aimed at controlling the condition rather than curing it.

Medical Treatment

Prostate cancers often shrink if their hormone environment is changed. Synthetic hormones that block testosterone (e.g. cyproterone acetate, flutamide) or that mimic a female environment (e.g. oestrogen derivatives) are used to damp down the disease. Unfortunately, female hormones can lead to male breast enlargement, and also reduce the male sex drive.

The male hormone testosterone is only made by the testicles if it receives a hormone signal from the brain. The latest hormone treatments (LHRH agonists e.g. buserelin, goserelin, leuprorelin) act directly on the brain ­ often via a nasal spray ­ to prevent this signal being given. This results in a so-called 'chemical castration' as the testicles stop producing testosterone. Unfortunately, side-effects of hot flushes, low sex drive and impotence are inevitable. A third of patients suffer a flare-up of disease symptoms in the first few weeks of treatment as testosterone levels initially go high before petering out.

Radiotherapy may be used to shrink the prostate gland, or to relieve the pain of bone secondaries. This takes the form of external beam irradiation or of radioactive iodine seeds placed in the gland itself. Radioactive bone-seeking substances (e.g. strontium) are beneficial in men with widespread bone secondaries. Unfortunately, chemotherapy with anti-cancer drugs is generally unhelpful.

Surgical Treatment

Removal of the testicles (orchidectomy) is occasionally performed in a drastic attempt to lower testosterone levels. If surgical castration is thought necessary, egg-shaped implants may be inserted in the scrotum which look and feel like the real thing.

Side-effects of the operation include hot flushes (similar to those of menopausal women), impotence, loss of libido and adverse psychological effects. Most men would prefer a chemical (hormonal) castration to a surgical one.

If the prostate tumour is small and localized, the whole gland is sometimes removed (radical prostatectomy) in the hope of curing the disease. This operation is done more frequently in the US than in the UK. A recent modification of the operation spares nerve bundles lying close to the prostate gland. This reduces the risk of sexual dysfunction and incontinence.

A new surgical procedure using a YAG laser to remove a malignant prostate gland shows promising early results.

Other treatments currently being investigated include cryotherapy (freezing the gland) and Microwave Hyperthermia.

The Future

Exciting new research has discovered substances called bolstered tumour-fighting growth factors within the prostate gland. These are natural substances produced by the prostate cells as part of the body's tumour-defence mechanism. Although treatment with these factors is a long way off, they offer an exciting possibility for manipulating prostate cancer successfully.

Another possible route to curing prostate cancer is by switching off cancer genes through gene therapy, although it will probably be at least 10 years before this treatment is available.

DIET AND PROSTATE DISEASE

The idea of eating for a healthy heart is now medically accepted ­ but the concept of eating for a healthy prostate is revolutionary.

Recent studies suggest that this is not only possible ­ but an important factor in the observed low incidence of prostate disease in certain parts of the world.

Men in China and Japan are less likely to develop prostate cancer, benign prostatic enlargement and prostatitis than Western males. This does not seem to be an inherited trait, as autopsy studies show they have just as high an incidence of hidden prostate cancer as American men. Something in the Eastern lifestyle seems to damp down prostate conditions so they do not progress into clinically significant disease.

If Eastern males move to the West, their prostate protection is lost. There is also evidence that Japanese males who do not emigrate, but who adopt a more Western diet, lose their traditional protection against prostatic disease.

One theory gaining in popularity is that the Eastern diet protects against prostate disease, while a Western-style diet is more likely to trigger prostate problems.

Dietary Plant Oestrogens

The traditional Japanese diet is low in fat, especially saturated fat, and consists of rice, soy products (e.g. soybeans, soymeal, tofu) and fish together with legumes, grains and cruciferous plants. The latter include exotic members of the cabbage and turnip families (e.g. kohlrabi; Chinese leaves). These are all rich in weak plant hormones (isoflavonoids, phytoestrogens) that are released during digestion ­ probably through bacterial fermentation in the intestinal tract ­ and absorbed into the circulation. These are thought to interact with natural male hormones to protect against benign prostatic hyperplasia, prostatitis and even prostate cancer.

This theory is strengthened by recent findings that blood levels of dietary oestrogens are up to 110 times higher in Eastern races compared to inhabitants of the West.

There seems to be a paradox, however. Environmental oestrogens from other sources (e.g. PCBs, dioxins, traces of female HRT and oral contraceptive Pills in drinking water, bovine oestrogens in pregnant cows' milk) are currently implicated in the increased incidence of prostate cancer and the rapidly falling sperm counts observed in Western males (see environmental oestrogens and sperm).

How can environmental oestrogens protect Japanese men against prostate cancer yet seem to cause it in the West?

The answer seems to be that plant oestrogens (unlike synthetic environmental ones) are sufficiently similar to natural human oestrogens to trigger the production of a protein called Sex Hormone Binding Globulin (SHBG). This protein mops up the dietary oestrogens, as well as endogenous male hormones. Once hormones are bound to SHBG they are effectively inactivated. This reduces the prostate gland's overall exposure to hormones and therefore lowers the risk of prostate problems.

The plant oestrogens may also have a direct effect on male hormone production and metabolism, plus an effect on tumour cell growth.

Dietary Antioxidants

Eastern males eat many more yellow, orange, red and green vegetables (such as red, yellow and green peppers, broccoli, spinach, etc.) than Western males. These are high in the antioxidant vitamins E, C and betacarotene. By mopping up dangerous free radicals formed within the body during the normal processes of metabolism, they reduce the risk of coronary heart disease and cancer.

As in politics, a free radical is a highly unstable entity that races round picking fights and causing damage.

The molecular version carries a negative charge. It desperately tries to neutralize this by colliding with cell components and stealing a positive charge or off-loading its own negative one.

Each body cell is bombarded with an estimated 100,000 oxidation reactions every day ­ the number is twice as high in smokers.

If molecular DNA is damaged through these oxidations, errors can occur in gene sequences, or cancer-causing genes may be switched on. This increases the risk of all types of cancer, including that of the prostate gland.

A diet high in antioxidant vitamins and minerals protects against cancer (and coronary heart disease) by donating or accepting an unpaired electron to neutralize the free radical's negative charge before it can damage the cells.

Eastern males naturally obtain much higher amounts of these important antioxidant vitamins than Western males.

The National Cancer Institute (US) recommends a daily intake of at least 6 mg of betacarotene to decrease the risk of cancer. An intake of 15 mg per day is desirable ­ but this is only achievable by taking food supplements as well as paying attention to diet. Some experts in the UK also suggest we take daily dietary supplements of 150 mg vitamin C and 30­40 mg vitamin E.

Fibre

Vegetables are high in insoluble dietary fibre which stays in the intestinal tract and absorbs excess male hormones excreted in the bile. This helps flush them through the bowels so they are not reabsorbed to cause an imbalance.

Zinc

Vegetables are also rich in zinc, an important mineral for prostate health. Zinc forms part of an enzyme which switches on certain genes in response to hormone triggers and controls the sensitivity of prostate tissues to sex hormones. Intakes of at least 10 mg zinc per day are needed to maintain prostate health. (See Chapter 20 for a list of foods that are rich in zinc.)

Dietary Saturated Fat

Latest research shows that men who follow a typical Western diet high in animal (saturated) fat have an increased risk of prostate cancer.

The more fat a man eats, the higher his risk of developing advanced prostate cancer. Saturated fat from red meat, mayonnaise, creamy salad dressings and butter seems to be most dangerous. There is no increased risk from any other dairy products such as milk or cheese.

Red meat is the food with the strongest positive link to advanced prostate disease. The researchers went so far as to recommend that males lower their intake of red meat if they want to reduce their risk of prostate cancer.

Instead, obtain essential fatty acids vital for prostate health such as linolenic and linoleic acids. Natural sources of these include nuts (e.g. walnuts) and seeds (e.g. pumpkin, sunflower; linseed). The WHO suggests that everyone should eat at least 30 g of nuts/seeds per day.