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Prostate Cancer Screening May Not Be As Effective As We'd Like To Believe

Posted Apr 04 2011 8:10am
The Times They Are a-Changin' - Bob Dylan

There once was a time when prostate cancer was most often diagnosed late in the course of the disease after the patient presented complaining of back pain w/absurdly elevated prostate specific antigen (PSA) levels.  Then someone had the bright idea to screen for prostate cancer by checking PSA levels (in addition to digital rectal examinations) in asymptomatic men after arbitrarily deciding to call all levels >4ng/mL abnormal.  However, we've never really proven that this early screening makes a difference in mortality.  After all, if we cure a disease that isn't going to affect mortality, what good are we doing.

Sure, we always read about the men who die from or because of prostate cancer, such as Frank Zappa (52yo), Johnny Ramone (55yo), Jerry Orbach (69yo), Telly Savalas (70yo), Dennis Hopper (74yo), Earl Woods (74yo), and Pierre Elliott Trudeau (80yo).  And we hear even more often from those who were successfully treated, such as Robert DeNiro (now 8 years post-diagnosis), Rudy Giuliani (10 years), Roger Moore (18 years), General H. Norman Schwarzkopf (18 years), Louis Farrakhan (20 years), and Senator Bob Dole (20 years).  But have we helped them live any longer than if we'd just watched & waited?  And at cost were these men "cured" with life changing side effects, eg incontinence, erectile dysfunction, proctitis & diarrhea.

In a study just published in the British Medical Journal , the authors concluded that over 20 years of follow up, mortality did not differ between those who were screened (1,494 individuals) and those were not (7,532 controls).  Perhaps, this finding was an anomaly.  But in fact, a systematic review & meta-analysis published last September (also in the BMJ)  of 6 randomized controlled trials involving 387,286 individuals  arrived at the same conclusion:  no statistically significant effect of screening on prostate specific and all-cause mortality. Back here in the States, the ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial also came to the same conclusion in March 2009 after following 76,693 men for 7-10 years.

When you think about it, these findings are consistent with the spate of studies suggesting that active surveillance is a reasonable option in those w/localized, low grade diagnosis .  Which might explain why  a study in JNCI questioned the value of a prostate biopsy based just upon PSA velocity .  If anything, this really begs the question as to why screen at all?  Sure, maybe if you have a family history of aggressive cancer leading to death at any early age.  But for the rest of the population, are we really doing them any good?

When the facts change, I change my mind.  What do you do, sir? - John Maynard Keynes


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