My second prostate related post for the week. (It's my age that lends an interest in the topic.)
It seems from this story that a single PSA test, which (as I recall) is often of limited use in working out what to do about prostate cancer that is already there, may be very useful as a predictor for advanced cancer:
A single prostate specific antigen (PSA) test taken before the age of 50 can be used to predict advanced prostate cancer in men up to 25 years in advance of a diagnosis, according to a new study published by researchers at Memorial Sloan-Kettering Cancer Center in New York and Lund University in Sweden. The findings should help physicians be able to identify men who would benefit from intensive prostate cancer screenings over their lifetime...Yet this article, which seems in need of editing, says next:
The results showed that the total PSA level was an accurate predictor of advanced cancer diagnosis in men later in life. The majority, 66 percent, of advanced cancers were seen in men whose PSA levels were in the top 20 percent (total PSA > 0.9 ng/ml). The average length of time from blood test to cancer diagnosis was 17 years.
While this data does not have any immediate implications for general prostate cancer screening guidelines...Why not? Sounds like a pretty useful thing to me.
It still leaves the problem that in the individual case you have no idea whether the person has a cancer that is going to become clinically significant in their lifetime. It seems likely that much of the treatment given for prostate cancer found on screening is unnecessary, we just don't know who needs it and who doesn't. Invasively treating someone who would never have become symptomatic is dreadful.
ReplyDeleteIt is hard to justify screening when you don't know whether you are harming or helping. That is why it is not recommended.
Geoff
I suppose it depends on what the diagnosis of "advanced" prostate cancer means. I assumed it meant the type that you would try to treat. And I assumed that having a test before 50 with a high PSA would just serve to advise the man that he would be wise to keep a regular check of his prostate as he ages, as he would appear to be at somewhat higher than average risk of getting the worse form of cancer. (Apart from having further PSA tests, I thought the digital exam would be of some use for such a man.) But I know little of prostates, apart from the fact that they seem like a design flaw.
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