Generations of patients and doctors have been steeped in the myth that any kind of cancer should be found as soon as possible and when found, removed. The image of a gray-haired doctor on television telling the frightened patient “if only we had caught it sooner…” has convinced us all that cancer must be diagnosed ASAP.
But it turns out that diagnosing prostate cancer sooner hurts more than it helps. For the last two decades many men over 50 have been regularly screened for prostate cancer with a blood test called PSA (prostate specific antigen) despite the fact that there was never any evidence that this test saves lives.
Last October the US Preventive Services Task Force (USPSTF) reviewed the available studies about screening for prostate cancer. Their preliminary recommendation was against routine screening of men at any age for prostate cancer. (I wrote about their recommendations at the time.) This week the USPSTF after considering public responses to their recommendations released their final recommendations, which are essentially unchanged. The USPSTF recommends against PSA screening for prostate cancer as it concludes that the benefits from screening are small or nonexistent and do not exceed the known harms of screening.
How is that possible? There is no question that many more prostate cancers have been diagnosed since the advent of PSA testing and also no question that the cancers diagnosed are at a much earlier stage than those found before PSA testing was routine. How can diagnosing prostate cancer more frequently and earlier not help?
To understand that we have to understand that prostate cancer is very common but rarely harmful. Prostate cancer increases in incidence with age, and grows very slowly. Prostate cancer frequently takes a decade or longer before it causes patients any harm. So many men with prostate cancer never develop any symptoms from it and die from some other cause at a ripe old age. Unfortunately, some men develop aggressive metastatic prostate cancer which cuts their life short, but we have no accurate way to distinguish which prostate cancer will remain indolent and which will be aggressive.
A consequence of this slow-growing but very common cancer that afflicts older men is that it’s very hard to show that early detection and early treatment actually helps anyone. The studies reviewed by the USPSTF showed that the life-saving benefit of PSA screening is either nonexistent or very small. If 1,000 men are screened for a decade with PSA testing, this will lead (many years later) to between zero and one life saved from prostate cancer. But much harm will befall those thousand men because of the testing. 150 to 200 of them will undergo prostate biopsies because of an abnormal PSA. One third of the men having biopsies will experience a significant adverse symptom as a complication of their biopsy, and one or two will require hospitalization because of a biopsy complication. Many of these biopsies will turn out negative (because PSAs are so inaccurate) but some others will diagnose prostate cancer. Those patients diagnosed with prostate cancer will undergo treatment, frequently surgery, radiation, or both. Surgical complications will cause one of the men to develop a dangerous blood clot and two of the men to have heart attacks. Forty of the men will become impotent or incontinent because of their radiation or surgery. That’s a lot of harm for very little, very uncertain benefit.
The specialists who (presumably with the best of intentions) have been making a living causing all this harm were indignant. The American Urological Association was “outraged”, but perhaps their outrage will lessen when they ponder how much their members have been paid to make tens of thousands of men impotent. An editorialist in the Annals of Internal Medicine who wrote in support of the USPSTF recommendations quoted Upton Sinclair who said “It is difficult to get a man to understand something, when his salary depends on his not understanding it.”
So I will start explaining to my male patients the known harms and the unproven benefits of PSA screening. For many patients this will be a slow and difficult psychological shift. Many patients will still request the test out of habit or simply because they don’t yet believe the new recommendations. That’s fine. They’re the boss. I only give advice.
In six years I will turn 50. I tell all my patients that I’ll celebrate by undergoing a colonoscopy for colon cancer screening. I will certainly not have a PSA checked.
What we urgently need is a new test that discriminates aggressive prostate cancer from the more common harmless prostate cancer, and we need less harmful treatment options. I have six years to wait for such advances. Meanwhile, a very nice man who has been my patient for over a decade is scheduling his prostatectomy in the next few weeks. I hope he does well.
All Routine PSA Tests For Prostate Cancer Should End, Task Force Says (Shots, NPR’s health blog)
Government task force discourages routine testing for prostate cancer (Washington Post)
Men Should Skip Common Prostate Test, Panel Says (Wall Street Journal)
Screening for Prostate Cancer: U.S. Preventive Services Task Force Recommendation Statement
USPSTF author insight video
Prostate Cancer Screening: What We Know, Don’t Know, and Believe (Annals of Internal Medicine editorial)
What the U.S. Preventive Services Task Force Missed in Its Prostate Cancer Screening Recommendation (Annals of Internal Medicine editorial)
National Panel Advises Against Prostate Cancer Screening (my post last year about the USPSTF PSA recommendations)
Important legal mumbo jumbo:
Anything you read on the web should be used to supplement, not replace, your doctor’s advice. Anything that I write is no exception. I’m a doctor, but I’m not your doctor.