The PSA test for prostate cancer: more harm than good?

Millions of men are tested each year for high levels of prostate-specific antigen, or PSA, which is designed to detect early signs of prostate cancer. The test is covered by insurance, so most men readily agree to it. After all, what's the harm?

Well, plenty. PSA screening, we now know, "leads to a substantial overdiagnosis of prostate tumors." Many of these cancers grow very slowly, and men with slow-growing prostate tumors may never have symptoms. However, once a man is told he has cancer, there is a a strong tendency to treat it, and treatment has serious, often harmful side effects: 20-30% of men treated with surgery and radiation will have long-term incontinence and erectile dysfunction.

There is a furious debate going on right now over the evidence for and against PSA screening. The debate started with a large-scale US study called PLCO, which found no benefit from annual PSA screening. Soon after that, the US Preventive Services Task Force recommending that most men should not get regular PSA tests.  They concluded:
"Many more men in a screened population will experience the harms of treatment than will experience the benefit.... The USPSTF concludes that there is moderate certainty that hte benefits of PSA-based screening for prostate cancer do not outweigh the harms."
The American Academy of Family Physicians agrees, and has adopted a clear recommendation:
"Don't routinely screen for prostate cancer using a prostate-specific antigen (PSA) test or digital rectal exam."
which I wrote about last November.

In contrast, the American Urological Association responsed to the USPSTF report by issuing a statement that it was "outraged and believes that the Task Force is doing men a great disservice." Prostate surgery is big business for urologists, which may have biased their reaction. However, to their credit the AUA modified its guidelines on PSA screening, which now state
"The [AUA] Panel does not recommend routine screening in men between ages 40 to 54 years at average risk."
For men ages 55 to 69, they recommend "shared decision-making," but they still insist that there is a benefit for men in this group. Their 2013 press release says "the highest quality evidence for screening benefit was in men ages 55 to 69 screened at two- to four-year intervals."

Why does the controversy continue? One reason is that a large European study, called ERSPC, reported a small benefit from PSA screening. The European study is actually a combined analysis of 7 studies in 7 countries, each of which was run a bit differently.  Five of the studies reported no benefit, and just two, from Sweden and the Netherlands, showed a benefit.

So what was going on in those two countries? Did they do screening differently, or treatment differently? Well, it seems they did. In a letter published in Uro Today on May 6, Ian Haines and George Miklos lay out an explanation: in the Swedish study, many more patients in the control group (the group that did not receive PSA screening) were treated with androgen deprivation therapy, ADT, which recent evidence indicates may increase the risk of death. Haines and Miklos published a more detailed analysis last October, accompanied by an editorial by Otis Brawley, the Chief Medical Officer of the American Cancer Society.

Brawley pointed out that
"the harms of screening have been consistently demonstrated in all screening trials to date."
He calls for "an objective panel of experts with access to all of the data" to address the controversy over the possible bias in some of the European trials. Carlsson et al. responded last month in the Journal of the National Cancer Institute, defending their methods, but Haines and Miklos fired back in the same issue, arguing that the benefits found in the European study "rests entirely on the ... Goteborg trial from a single city.

Regardlesss of the evidence from that one city, though, the evidence today is strong that until we have much better treatments for prostate cancer, routine screening with PSA tests causes more harm than good. The side effects of surgery can be life-altering and devastating. Guys: unless you have a special reason to be concerned about prostate cancer, tell your doctor "no thanks" if he offers you a PSA test at your next checkup. That's what I did.

1 comment:

  1. the logic is that some information-gathering is bad, since it might
    (and maybe in practice often does) lead to wrong decisions ?
    You'd better critisize the decision-leading-process then rather than the
    information-gathering process (IMO)

    gsgs

    ReplyDelete

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