PSA featured throughout JAMA Letters

If you want to capture the pulse of American medicine, open the Journal of the American Medical Association (JAMA). This month JAMA featured four Letters to the Editor with a sharp focus on prostate cancer-specific antigen (PSA) and prostate cancer. Last week I argued now is the time to dichotomize prostate cancer. JAMA understands we are approaching critical mass.

Here's the central Letter: Recommendations on Use of Prostate-Specific Antigen for Prostate Cancer Screening. [1]

Here are the three responses: [2] [3] [4]

These Letters raise two issues I see throughout publications on PSA screening and prostate cancer. The first issue is opponents to widespread PSA screening routinely ignore PSA permutations and kinetics. In the Central Letter, Dr. Marc Garnick writes:

Quote:
Unfortunately, a noninvasive screening biomarker for prostate cancer that identifies those who will benefit from treatment does not yet exist. [1]

Dr. Garnick is absolutely correct, but his statement suggests PSA is the quintessential element in prostate cancer risk identification. Like every other cancer screen in medicine, a single test cannot prove cancer. To prove cancer, physicians need tissue (a biopsy). PSA is meant to help determine which patients are at high risk for prostate cancer. I cannot think of a single blood test, for any cancer, that identifies cancer and identifies cancer particularly amenable to treatment. Medicine just isn't this good.

Perhaps primary care physicians don't routinely collect free PSA or calculate percent free PSA. They probably don't calculate PSA density, PSA velocity, or PSA doubling time. Urologists use all of these in conjunction with PSA to stratify prostate cancer risk.

The second issue is a philosophical disagreement about medical decision-making and physician-patient dynamics.

Garnick writes:

Quote:
[. . .] the [United States Preventive Services Task Force's] evidence-based recommendations should be welcomed by men who will be spared unnecessary harm from treatment for PSA screen–detected prostate cancer. [1]

(Again, PSA screening doesn't detect prostate cancer.) When do we ignore patient autonomy? The decision to screen and biopsy for prostate cancer should be shared decisions between a patient and his physician. Physician have a responsibility to educate and advise patients about their health. In the end, the decision to collect PSA or undergo biopsy belongs to the patient. The primary care physicians, statisticians, and epidemiologists of the USPSTF disagree; they firmly believe the evidence against prostate cancer screening is so fundamentally sound it wholly negates a conversation between a man and his urologist.

Just because a screening exam reveals an elevated PSA doesn't mean a patient must be immediately referred to a urologist. And if a patient is referred to a urologist for elevated PSA, the urologist will repeat PSA testing and review PSA permutations (like percent free PSA) and kinetics before submitting a patient to biopsy. If the patient decides he wants to undergo biopsy, the urologist treads with a healthy respect for potential complications. Urologists are well informed of the risks of prostate biopsy (epidemiologists aren't the ones answering early-morning emergency room pages for patient fevers after biopsy).

What's at stake is bigger than a screening test for prostate cancer. Hiding beneath the core PSA debate is a quiet assault on shared decision-making in the exam room.

References

  1. JAMA 2012;307(13):1372. doi:10.1001/jama.2012.396
  2. JAMA 2012;307(13):1372-1373.doi:10.1001/jama.2012.397
  3. JAMA 2012;307(13):1373.doi:10.1001/jama.2012.398
  4. JAMA 2012;307(13):1373-1374.doi:10.1001/jama.2012.399

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Bayne pic Christopher Bayne is a urology resident at The George Washington University. He keeps a blog called Urinalysis and Tweets at @CBayneMD.

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