On QI the other night, one of the panellists, Alan Davies, asked "Could someone please clear up once and for all the link between the moon and tides?". It's one of those phenomena that most of us sort of know but can't easily explain, rather like what it is that determines what day Easter Sunday falls on. I sometimes feel this way about prostate cancer testing. I know for example that the risks associated with treatment often outweigh the benefit. I know more men die with prostate cancer than from it. I know a man can have a normal PSA result and still have prostate cancer, just as he could have a high PSA test and not have prostate cancer. I also know that for some men, a PSA test will help find prostate cancer at an early stage before it has a chance to spread.
However, I find it very difficult to explain in a clear and concise sentence why no government in the world has a prostate cancer screening program. And I work in health promotion. It is therefore completely understandable that men should find it confusing too and explains why so many unquestioningly have an annual PSA test without any real understanding of what they're entering into.
Almost everyone accepts the notion that when it comes to cancer early detection is the best protection. Certainly for most cancers this is the case - take bowel cancer for example; if found at the earliest stage, more than 90% of cases can be cured. That's why Cancer Council is campaigning hard for a fully implemented screening program, just as we have for breast and cervical cancer. But with prostate cancer it is not so simple.
The main issue is there is currently no screening test to determine which prostate cancers are slow-growing and unlikely to cause harm, and those which are aggressive and need treatment. Such a test is the holy grail of prostate cancer research. While there is no doubt that treatment options are improving all the time, it is still the case, according to NSW data, that 77% of men who have radical surgery or radiotherapy will have long-term impotence and 12% will experience urinary and sometimes bowel incontinence. These are significant side-effects when you consider that in many cases the prostate cancer may never have developed to become life-threatening within the lifetime of the man concerned. Clear as mud?
Thankfully public health guru, Professor Simon Chapman, along with other leading experts, has decided to tackle this very topic in his new book, Let Sleeping Dogs Lie? What men should know before getting tested for prostate cancer. Like any good author Prof. Chapman has been able to articulate where many others have failed, and provides a compelling and insightful discussion of the many complex risks and benefits associated with prostate cancer testing, as well as a balanced review of the current evidence. You can download it for free here.
Cancer Council's position is to advise men to have an informed discussion with their doctor about the benefits and limitations of prostate cancer testing and treatment, taking into account their age and family history.
As for the moon and the tides, well it's something to do with the gravitational forces exerted by the sun and the moon, and the rotation of the earth. And Easter, well that all depends on the first full moon after the northern hemisphere's vernal equinox. But don't just take my word for it, as with prostate cancer testing, I'm sure there are some wonderfully clear and well-written books on these topics.
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