Date Published: 23 February 2006
Making sense of the PSA test for prostate cancer
Male relatives of prostate cancer patients need more information in order to help them understand the possible familial risk of the disease, and to decide whether or not to have a PSA* test, according to research published in the British Journal of Cancer this week.
The benefit of PSA testing as a screening tool remains uncertain. It may have value for screening first degree relatives of men with prostate cancer who are consequently at an increased risk of developing the disease ? about 10 to 15% of British men ? but this approach needs to be fully tested. However, two Cancer Research UK-funded studies at The Institute of Cancer Research have found that such a targeted screening programme would be difficult to run and may have a low uptake by relatives invited to have their PSA levels tested.
There are many unknowns about the PSA test. It can often detect problems in the prostate at an early stage, but a positive result does not always mean cancer. As such, getting the result of a PSA test can be a confusing situation that requires clear information and advice from health professionals.
The studies were designed to look at how the PSA test could be practicably used as a possible screening test for relatives of prostate cancer patients. Results showed that some patients were reluctant to involve their family members in screening. Many of the relatives who did respond to the suggestion of screening had already had a PSA test, but took part because they still felt they needed more information about prostate cancer.
The PSA test has not been shown to work as a screening test for the general population, although trials are ongoing. One concern is that a raised PSA level, while not always indicative of prostate cancer, nevertheless sometimes leads to invasive investigations that then find the situation to be normal. There is also doubt over whether screening using PSA tests would reduce prostate cancer deaths overall.
The NHS currently recommends detailed information that should be supplied to men who have requested a PSA test so they can make an informed choice. The authors of The Institute's studies conclude that further specific advice may be necessary for prostate cancer patients with first degree male relatives so they can understand familial risk factors.
Dr Jane Melia, from The Institute's Cancer Screening Evaluation Unit, funded by the Department of Health, said:
" We asked prostate cancer patients if we could invite their brothers and sons to have a PSA test but found acceptance by those invited to be fairly low. One reason for this was that many of the invited relatives had already had a test. Some patients did not agree to the request because they were reluctant to involve their relatives in screening.
_ One reason for the patients' reluctance was that not all of them had told members of their family they had cancer. Some men were concerned about the additional diagnostic tests following a positive screening result. Encouragingly, among the relatives who did take part, only a small number experienced high levels of anxiety."
A prostate cancer screening programme would increase the number of cases being diagnosed. Not all prostate cancers are aggressive, however, and other research is underway to find molecular markers that would allow the accurate assessment of how aggressive a prostate cancer is. Such markers would enable doctors to reassure some men with a positive test result, and choose the most appropriate treatment for others.
Dr Melia added:
" Our concern is that no one really knows how best to use this test. Close male relatives of prostate cancer patients form a relatively small group in the population, so setting up large-scale randomised controlled trials is not easy. While we wait for the data to accumulate, prostate cancer patients need information and support to help them understand familial risk so they and their relatives, if then told, can make a fully informed decision about the PSA test."
It has been estimated that inherited genes could account for up to ten per cent of all cases of prostate cancer. Men with a family history of prostate cancer in a first degree relative have an increased risk of developing the disease ? two to three times higher than on average.
Dr Lesley Walker, director of cancer information at Cancer Research UK, which owns the British Journal of Cancer, said:
" Cancer Research UK fully supports cancer screening programmes where they have been shown to be effective in reducing mortality. In the case of PSA, the evidence so far suggests it is useful for diagnosing and monitoring men who already have symptoms associated with prostate cancer.
_ There is an argument for thinking it could also be useful for screening men at a higher relative risk of the disease, such as close relatives of prostate cancer patients. This research is an early step towards evaluating the feasibility of such an approach."