Prostate cancer generally occurs in men beyond middle age and is uncommon in men under 45 years old.
The exact cause of prostate cancer is unknown, but in some cases it may run in families. It is becoming more common in the developed world. Men who eat a high-fat diet or who are black may have an increased risk of developing prostate cancer
Prostate cancer may arise from an imbalance of certain body chemicals, called growth factors, that control the growth and division of cells in the prostate gland. There may also be damage to the genetic material (DNA) in the prostate cells, causing uncontrolled growth of the cells.
Prostate cancer usually develops in the outer part,pf the prostate gland. Cancer often causes a change in the texture of the gland making it firmer, which may be detected by a doctor during a digital rectal examination (DRE).
Prostate cancer may also be diagnosed when prostate tissue is removed during surgery to reduce the size of an enlarged prostate, or be suspected because of an abnormal blood test (prostate-specific antigen - PSA) result.
Spread of prostate cancer to the lymph nodes, lungs and bones:
In time, cells from a prostate cancer may invade local tissues or break away and spread to other areas of the body via the bloodstream or lymphatic system.
When these cells reach a new site they may form a new cancer, referred to as a secondary tumour or metastasis. The lymph nodes and bones, as well as the lungs, are the areas most commonly affected by these secondary tumours.
The development of low back pain in association with symptoms of difficulty in passing urine may be a warning that prostate cancer is present. Most cases of back pain however are due to arthritis of the spine.
Biopsy of the prostate:
A doctor may suspect prostate cancer because of the way the prostate gland feels when he carries out a digital rectal examination (DRE) through the back passage (rectum), or because the level of prostate-specific antigen (PSA) in the blood is raised above the normal upper limit of 4 ng/ml.
It is important to remove some tiny pieces of prostate tissue so that it can be examined to check whether it really is cancer; this is called a 'biopsy'.
Several samples of prostate tissue are removed after antibiotics have been given, using a very fine needle inserted via the rectum. The tissue is then examined under a microscope to look for cancer cells.
Ultrasound is often used to 'guide' the biopsy needle. A finger-sized probe is inserted into the back passage (rectum). The probe passes inaudible sound waves through the prostate which bounce back off the tissue and produce an image of the prostate on a computer screen. The test is uncomfortable but not very painful, though a needle prick may be felt as each biopsy is performed.
After a prostatic biopsy, patients may sometimes see some blood in the urine, semen or bowel motions. Occasionally, infection may occur, in which case, further antibiotics will be necessary.
Investigations for prostate cancer :
Prostate cancer can sometimes be detected by the doctor feeling the prostate with his finger through the back passage (rectum). This is called a digital rectal examination (DRE).
Prostate-specific antigen (PSA) levels in the blood are usually much higher than normal in men with prostate cancer. The upper limit of normal for PSA is 4.0 ng/ml. Levels only slightly higher than normal are often due to benign prostatic hyperplasia (BPH). In general, the higher the PSA level, the greater the risk of cancer.
A number of X-ray and other imaging techniques may be used to check whether the cancer has spread.
Ultrasound may also be helpful in diagnosing the extent of prostate cancer. As in a biopsy, a finger-sized probe is inserted into the back passage. The probe passes inaudible sound waves through the prostate which bounce back off the tissue and produce a picture of the prostate on a computer screen.
A bone scan highlights areas of abnormal blood flow in bone, which may be due to a cancer which has spread from the prostate. An injection is given into the arm and a scan of the whole body performed several hours later.
An MRI or CT scan takes several pictures at different points throughout the body, rather like slices through a loaf of bread. These scans can produce detailed images of the prostate, which may show the extent of any cancer if it is present. MRI and CT scans can also show whether secondary tumours have formed in other tissues. You may find these tests a little claustrophobic, but they are not at all painful.
Radical prostatectomy :
If prostate cancer has not spread to other areas of the body, the entire prostate with the tumour can be removed in an operation known as a radical prostatectomy.
The procedure is carried out under a general anaesthetic and takes 2-3 hours. You will usually be able to go home within 7 days. A fairly long period of convalescence is needed after the operation, usually 6-8 weeks, and a catheter will be needed for 2-3 weeks. Patients often feel weak and tired for several months after surgery.
There is now only a small (less than 3%) risk of incontinence but about a 70% chance of impotence (impaired erections) following radical prostatectomy. Recent improvements in the technique mean that these risks are lower than they used to be.
After a radical prostatectomy, if the cancer has been removed, the amount of prostate-specific antigen (PSA) in the blood falls to zero and stays unrecordably low.
A rise in the blood level of PSA after radical prostatectomy usually means that cancer tissue is still present or has recurred and that further treatment may be necessary.
Radical radiotherapy :
Radical radiotherapy is a common treatment for patients who have prostate cancer that has not yet spread to other areas of the body.
The prostate is bombarded with a beam of radioactive particles, like those released from an X-ray machine, which can kill the cancer cells.
You will normally receive radiotherapy as an outpatient. Treatment usually involves two 2-week courses of radiotherapy, with a rest period of 2 weeks in between.
Radiation treatment is not painful, but radiotherapy does have side-effects and you may experience diarrhoea, bleeding and discomfort in the back passage (rectum), painful or frequent urination, or occasionally blood in the urine. About 25-50% of patients receiving radiotherapy also become impotent (they cannot achieve an erection).
Even when radiotherapy does not kill all the cancer cells in the prostate, the treatment may still have slowed the spread of the cells to other areas of the body.
A rise in the blood level of PSA at any time after radiotherapy usually means that other treatment is necessary.
Cytoreduction followed by radiotherapy:
If prostate cancer has spread into the tissues surrounding the prostate, but there is no evidence of more distant secondary tumours, a course of 'cytoreduction' therapy, combined with radiotherapy, may be suitable.
Cytoreduction means 'shinkage of cells'. In cytoreduction therapy, the patient is treated with drugs (usually given by injection) that block the natural male hormone for about 3 months. This causes the prostate cancer to shrink ('downsizing'). Radiotherapy can then be given to kill any remaining cancer cells.
Cryosurgery :
Cryosurgery is a new technique that involves killing prostate cancer cells by freezing them.
The technique is performed under general anaesthesia and takes about 1 hour. Up to six probes are introduced through the skin into the prostate to freeze the tissue. A catheter will be necessary for a few days after the operation.
Unfortunately, the side-effects of this procedure include loss of erections. Patients also may experience pain and difficulty in passing urine, but no bleeding occurs.
This technique is still experimental and no long-term results are yet available.
Hormonal control of prostate cancer -drug therapy and surgery :
Once prostate cancer has spread to the lymph nodes, bones or lungs, a remission (temporary interruption of growth) may be achieved by depriving the cancer cells of the male hormones (androgens), which it requires to grow and spread.
The release of the male hormone testosterone by the testes is stimulated through a hormonal pathway. The hypothalamus in the brain releases a substance called LHRH, which stimulates the pituitary gland, at the base of the brain, to produce another hormone called LH. LH, in turn, stimulates the testes to release testosterone.
If the action of LHRH can be blocked, LH will no longer be produced and the testes will no longer produce testosterone. This can be done by giving a regular injection into the skin of the abdomen of a so-called LHRH analogue.
The production of testosterone can also be reduced by the surgical removal of the testes. This operation, which is permanent, is called an orchidectomy.
Following both treatment with either LHRH analogues or orchidectomy, male hormones will still be released from the adrenal glands. The action of these hormones can, however, be blocked by giving antiandrogen tablets. This combination of treatments is called 'maximum androgen blockade'.
After treatment with LHRH analogues or orchidectomy, men usually lose their sex drive and ability to develop erections, and may also suffer hot flushes as women do after the menopause.
Hormone-escaped' prostate cancer :
Prostate cancer that has spread to other areas of the body will almost always shrink if deprived of male hormone. However, most prostate cancers, after a period of response to hormone therapy, begin to grow again. This is called 'hormone escape' (relapse).
Unfortunately, no effective alternative therapy is yet available, though a number of experimental agents, such as growth factor inhibitors and anti-tumour vaccines, are currently being tested.
Patients with hormone-escaped cancer may have considerable bone pain from secondary tumours in the bones. Radiotherapy and other measures, including injections of strontium 89 (a radioisotope), may help to reduce the pain.
Help for patients with hormone-escaped cancer may be
available from the 'palliative' cancer care teams. These usually
comprise nurses and doctors who are trained to look after
patients with advanced cancers.
Prostate cancer may arise from an imbalance of certain body chemicals, called growth factors, that control the growth and division of cells in the prostate gland. There may also be damage to the genetic material (DNA) in the prostate cells, causing uncontrolled growth of the cells.
In time, cells from a prostate cancer may invade local tissues or break away and spread to other areas of the body via the bloodstream or lymphatic system.