Thirty years ago prostate cancer was regarded as an old man's disease because it was usually diagnosed in men over 65 who had problems with the 'water works', or had advanced prostate cancer symptoms. Now it is more often diagnosed in younger men through a blood test called PSA.
In England and Wales, over 30,000 men per year are diagnosed with prostate cancer and 10,000 men per year die of the disease. We don't fully understand the causes of prostate cancer, but it is probably linked to diet and genetics. Our western diet, high in dairy, saturated fat, and calories, is associated with prostate cancer, as it is with breast and bowel cancer. Some ethnic groups, particularly Afro-Caribbean men, seem to be more susceptible. A few men seem to be at very much higher risk, related to an inherited gene mutation similar to the breast cancer genes BRCA1 or BRCA2.
Research has suggested that the drug, dutasteride, might help prevent prostate cancer but more work is needed to find out which men would benefit from it. Eating a healthy diet, low in saturated fat with plenty of fresh fruit and fresh vegetables and taking regular exercise can reduce prostate cancer risk.
In most prostate cancer cases only the prostate gland is affected and many men have no symptoms. However, 20 per cent of the men diagnosed with prostate cancer in the UK first went to their doctor complaining of severe pain and were diagnosed with prostate cancer that had already spread – often to the bones.
From middle age onwards men often have problems urinating but this is usually benign enlargement of the prostate gland. Only a few men with these problems will have prostate cancer.
If we could study, under a microscope, the prostate gland of every man over 60, most men would actually have signs of prostate cancer. Yet only a tiny minority would ever come to harm from it.
We badly need better treatments for men who have the aggressive form of the disease – the "tiger". But most men's prostate cancer is harmless – the "pussycat" - and for these men any treatment they receive is unnecessary. But, for now, there is no absolutely reliable test to distinguish between the two.
The PSA Test and consequences
A very large European trial of screening using the PSA test suggests that for every man whose cancer is cured as a result of screening, 47 more will receive unnecessary treatment. Such treatments like radiotherapy and surgery can cause very severe side effects.
The PSA (Prostate-Specific Antigen) is a protein produced by both healthy and cancerous prostate cells, which can be measured in the blood. Raised PSA levels can be a sign of prostate cancer. But,
most men with a raised PSA level do not have prostate cancer
some men with a normal PSA level do have prostate cancer
We still cannot tell whether a prostate cancer detected by PSA is a 'tiger' or a 'pussy cat'.
The pros and cons of this test should be carefully weighed up, and discussed with the GP. In general, if the PSA level is raised, the next step will usually be referral to a urologist, who will arrange for an ultrasound scan via a probe in the rectum (the back passage), and a biopsy. If the biopsy samples show prostate cancer, and provided other tests such as a MRI scan show no evidence of cancer anywhere else, there are usually three options:
1. No immediate treatment but the condition is monitored. This avoids treatment where the prostate cancer shows no signs of getting worse, and has advantages and disadvantages.
2. Surgery, or radical prostatectomy, either by an open operation, laparoscopy, or robotic surgery risking side effects of impotence and incontinence.
3. Radiotherapy, either by external beam radiotherapy (including IMRT), or using radioactive seeds implanted into the prostate (brachytherapy). The main side effects are bowel and urinary problems.
We do not know which of these options is best, and evidence suggests that the outcome is very similar. This means patients are often given the choice – which can be very hard.
If a man is prepared to accept the uncertainties around these tests and treatment of prostate cancer, then a PSA test may be the right thing to do. If not a PSA test may not be appropriate. Another urine test called PCA3 is also being investigated and results might help to reduce some of the uncertainties in the future.
For men whose cancer has advanced beyond the prostate, treatment options may be different. More information is available on the Cancer Research UK's CancerHelp website.
Professor Malcolm Mason
Cardiff University
Cancer Research UK Prostate Cancer Expert
