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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: derekb.lowe@gmail.com Twitter: Dereklowe

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March 12, 2010

The PSA Test for Prostate Cancer: Useless

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Posted by Derek

The discoverer of the prostate-specific antigen (Richard Ablin) has a most interesting Op-Ed in the New York Times. He's pointing out what people should already know: that using PSA as a screen for prostate cancer is not only useless, but actually harmful.

The numbers just aren't there, and Ablin is right to call it a "hugely expensive public health disaster". Some readers will recall the discussion here of a potential Alzheimer's test, which illustrates some of the problems that diagnostic screens can have. But that was for a case where a test seemed as if it might be fairly accurate (just not accurate enough). In the case of PSA, the link between the test and the disease hardly exists at all, at least for the general population. The test appears to have very little use in detecting prostate cancer, and early detection itself is notoriously unreliable as a predictor of outcomes in this disease.

The last time I had blood work done, I made a point of telling the nurse that she could check the PSA box if she wanted to, but I would pay no attention to the results. (I'd already come across Donald Berry's views on the test, and he's someone whose word I trust on biostatistics). I'd urge other male readers to do the same.

Comments (22) + TrackBacks (0) | Category: Biological News | Cancer


COMMENTS

1. dearieme on March 12, 2010 11:58 AM writes...

Everyone who has read Gerd Gigerenzer's book on Risk already knew that PSA testing was dud. GG is also interesting on breast screening.

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2. PharmaHeretic on March 12, 2010 12:57 PM writes...

The worst part is that biopsy or treatment for prostate cancer often causes more problems than the disease. In most men, especially over 65, treating only if absolutely necessary (very aggressive forms) is a far better option.

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3. Bob in FWB on March 12, 2010 1:33 PM writes...

I'd feel much better if they decided the digital exam didn't do any good!

My grandfather (on my dad's side) had, and I believe died of, prostate caner, so I think that puts me into the "get the test, maybe" category. But a 3.8% detection rate? And even *that* was better than the digital exam? I'll need to discuss with my doc the next time I'm there, but it kinda sounds like "if you're not showing symptoms, you're OK."

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4. Bob in FWB on March 12, 2010 1:36 PM writes...

As a follow-up, I did have both the digital and blood test when I hit 40. Both were OK, but now I'm wondering if there's any point, in the absence of symptoms, to re-doing either of them in the future.

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5. emjeff on March 12, 2010 2:35 PM writes...

I won't do either unless I'm having some issues (I'm 46). Why subject yourself to the worry and possible problems from medical procedures?

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6. retread on March 12, 2010 7:23 PM writes...

This retired MD agrees with Derek and, of course, the originator of the test, and has never had one. The evidence that it did any good was never there.

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7. Don B. on March 12, 2010 9:00 PM writes...

I have had a number of friends/colleagues that worked on large scale organic chemistry. When their PSA valus shot up, the prostates were removed & were malignant inside the cspsule. Some have passed away from old age but many are still alive. If you shuffle papers at C & EN you are probably not at risk.

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8. Anonymous BMS Researcher on March 12, 2010 10:27 PM writes...

The fundamental problem with a screening test is that unless the condition is quite common, even a modest false-positive rate will mean false positives will outnumber true positives. One can do a Bayesian analysis, or one can just use simple arithmetic: prevalence times sensitivity equals true positives, while (1-minus-prevalence) times specificity equals false positives.

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9. befuddled on March 13, 2010 12:37 PM writes...

@#2, PH:
But how do you know if you have a benign or aggressive form of cancer until you've had a biopsy at the very least. Sure, for many men "watchful waiting" is the best option even if they have cancer, but for which men and for how long?

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10. Emmett on March 13, 2010 11:32 PM writes...

Seeme to me like the health professional and Professor Richard Aldrin is worried about the cost of a simple blood test. How much does a blood test cost compared to cancer?

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11. Retread on March 14, 2010 10:20 AM writes...

Emmett: Quite right that the originator and yrs truly are concerned about cost, but the cost we're worried about isn't financial. It's the cost of permanent side effects (impotence, incontinence, mishaps due to general anesthesia, surgery etc. etc. ) due to diagnostic maneuvers the PSA test causes to be done. We know these will happen and that they have happened.

These costs must be balanced against the reduction in mortality from the disease (which has never been shown to my satisfaction, explaining why I never had the test).

Contrast PSA to the Pap smear which has virtually eliminated deaths from cancer of the cervix.

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12. pergurd on March 14, 2010 8:02 PM writes...

PSA is only designed to determine size of the gland, not what is causing it. That said, the PSA does have value in helping the practitioner determine size and thereby assisting with the bph diagnosis.

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13. Steven M Rauscher on March 16, 2010 8:25 AM writes...

I had a physical yesterday morning and asked my doctor his opinion on the PSA controversy. He had an interesting perspective. He doesn't advocate PSA screening for men over 65. (I'm 56 by the way). However, he does advocate it for men in the 50-65 age range.

He is more sanguine about the incidence of ED and incontinence in men undergoing prostatectomies. He believes the statistics include the results of both the good surgeons and the mediocre and horrible surgeons. He believes that the ED and incontinence rates are much lower with the best surgeons.

So he believes that if you are age 50-65 and you are fortunate to live in an area where you can get access to one of the better surgeons, PSA screening makes sense.

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14. retread on March 16, 2010 9:11 AM writes...

#13 Yes, but as a layman how are you going to differentiate the "good surgeons' from the "mediocre and horrible surgeons". No problem for me, being an MD. After practicing a while in a given area you find these things out very quickly. Some of the worst MDs have the most devoted clientele. Also, even the best have complications.

Absence of evidence is not evidence of absence, but what data we have on PSA is unimpressive, and not worth the small but definite risks associated with diagnostic maneuvers.

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15. DavidE on March 16, 2010 11:24 AM writes...

So at 41, when I started having issues, pain in my leg what would have had me do? Without the results of a PSA test my GP would have conducted more more tests (more expensive as well), in order to properly diagnose my Stage IV PCa.

It's not the test that is being over used, it is what that is being done owth the results of the test. Not everyone should jump right into treatment.

It's not OVER testing, it's over TREATMENT that is the issue.

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16. Claude Merrin MD on March 22, 2010 10:45 AM writes...

Dr Richard Ablin is not the discoverer of Psa.Psa was discovere by Dr Ming Chu at Roswell Park cancer institute.

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17. Jack on April 8, 2010 11:54 PM writes...

Interesting to read all the comments. I am 68 yrs old. I live in London England. My medical care is totaly free. I had my PSA checked free every year for the last ten years. It slowly built up from 4.5 to 6.7 a year ago. My last Psa test three months ago was 9.5. So they sent me for an MRI scan. It showed a small dark area. So I was given a targeted twelve needle biopsy. One sample was positive wih a gleason 3/4. Over the last few weeks I have had the first of several interviews with different specialists specialising in the differing solutions ie: keyhole surgery removal; straight surgical removal; HIFU; Watchful waiting etc. The final choice will be mine. Incidentaqlly three weeks ago, after diagnosis I radically changed my diet. After the first ten days my PSA had dropped to 7.6. I don't doubt that the original suspect area is still there. But all the medics I have seen, agree that if I do nothing at all, I will probably still be around after another ten years and maybe longer. What makes my situation more relaxed is the ease of access I have to all the surgical specialists who might end up doing the work on me. Again, all totaly free. Plus knowing whatever surgical solution I choose, will also be totaly free. Here in the UK the people dealing with the prostate problem are not your local doctor, or a colleague of his. Your doctor can only send you for a PSA test. Usually the local hospital. Once a condition is suspected, one is in the hands of total professionals at the nearest hospital that has specialists who are doing their particular job every day. And again, all totaly free. Prostate cancer is a serious problem for guys. And I can only sympathise with you guys in the USA having to worry about the cost and choice of doctor on top of it. But I would recommend staying on top of any suspected problem by getting all the information you can from the best possible source. It's only then that one can make an intelligent informed choice.

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18. Grape on May 13, 2010 2:24 PM writes...

I had a free PSA test done in the "Man Van" which is funded by private Donations. I'm in Canada and it costs me $27 for a PSA test (we have universal 'free' healthcare too). I saw on a website (Everydayhealth.com) that a guy should not ejaculate 48 hrs before a PSA test - this does not make sense to me - wouldn't the blood PSA level logically be lower if you just ejaculated? I reason that you just got rid of a bunch of PSA in the semen, the body is busy replenishing it, the prostate or semen gland would be picking it up out of the blood, thereby lowering the amount in the blood?

"Ejaculation can cause your PSA to rise briefly, so you should abstain from sexual activity for at least 48 hours before having your PSA level tested."

Anyway, my test resulted in 0.72 ug/l; I am 46 and this is well below the 2.5 ug/l upper limit they specified, and I had ejaculated an hour before the test. I asked the nurse and she said it didn't matter. I guess I'll live to see another day...

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19. WardB on June 14, 2010 4:44 PM writes...

I agree with DavidE.
This is all ludicrous. None of these comments seem to be comming from people who have had to face serious cancer. I have a close friend who's dad died from prostate cancer.
I am 60 years old and a year ago (May 10) I had a physical and my physician ordered a PSA test without informing me. It came back 75.9. I had biopsies and they came back with a Gleason score of 9. Scans and more biopsies show it had progressed to lymph nodes up my back. Of course I am on treatment (no surgery). One year later I had a another physical by the same doctor. He said correctly that if we had not performed that PSA I would be dead today.
People this is not about the PSA test or screening it's about doctors not being informed of proper procedures when a PSA implies the possibility of cancer. I am an engineer and I find medical practitioners most disturbingly uncoordinated and unprepared but I am very pleased I had the doctor that I did one year ago.

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20. Jay on July 7, 2010 10:57 AM writes...

I have a question for Jack in comment #17. He said- "Incidentally three weeks ago, after diagnosis I radically changed my diet. After the first ten days my PSA had dropped to 7.6."

I would like to ask him what exactly did he change in his diet that made the difference in PSA levels?

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21. Daniel on December 14, 2010 1:44 PM writes...

Interesting comments. I'm a 50 year old. Just had a physical for a new job. A psa. was not required but the Doc. said I should get that and a colonostomy because I've hit the 50 year mark. I'm curious as to why I/we become anxious when we go to the Docs. or for tests? I feel like I'd rather go after the Taliban in Wiziristan. Can anyone relate???
Any tips for handling this medical stuff???
I pray and think of my loved ones but I still feel so damn tense. Well God bless you all. Take good care of yourselves and Merry Christmas.

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22. V W on October 11, 2011 7:55 AM writes...

What is the correlation ratio between PSA and biopsy? One expert comment today says they are highly correlated. If true, it seems smart to get the PSA test regularly. Why would you pass up a simple, convenient, inexpensive test that can indicate whether you should get a "no fun at all," expensive biopsy? The answer, I think, lies in the correlation ratio: are high /rising PSA's correlated with biopsy results? I believe they are; prove me wrong.

To those who want to know what happens to those of us who get treated: surgery at age 66 allowed me to teach four more years in two more countries. At 74, I am enjoying our family, working in my shop, and tramping the rivers. I know men who opted for radiation. Both surgery and radiation are much better than just a decade ago.

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