Questioning Medicine: Prostate Cancer Screening

Andrew Buelt, DO, and Joe Weatherly, DO, are family medicine residents in St. Petersburg, Fla. Together, they co-produce the podcast Questioning Medicine, where they deconstruct issues confronting today's clinicians. In this guest blog, Buelt gives his take on the overuse of prostate cancer screenings

Let the Prostate Be

As prostate cancer awareness month just ended, prostate cancer screening seemed a fitting subject for this week's blog.

Those who know the evidence might think this argument pits European practices against our own domestic actions. Almost like a Ryder Cup for prostate screening. However, I recently saw that almost 50% of patients admit to undergoing lubed finger insertions and blood tests, which we know to be fairly inaccurate, in the last 12 months.

In a Research Letter in JAMA Internal Medicine by Sammon et al., the fact that so many physicians are still screening for prostate cancer makes my evidence-based medicine soul cringe. In a 2012 survey, the authors found that among 114,544 respondents, 37% had undergone screening. Higher socioeconomic status nearly doubled a man's odds of being screened (odds ratio 1.91, 95% CI 2.69-3.34).

Prostate cancer screening has been placed in the no-go category by the U.S. Preventive Services Task Force and the Choosing Wisely campaign, as well as by many other major medical associations.

Even the American Urological Association, which stands to lose the most money from reduced screening, states, "Men ages 55 to 69 ... should talk with their doctors about the benefits and harms of testing ...." In my opinion, they deserve a standing ovation for speaking to the evidence and not to the money, as the American College of Obstetrics and Gynecologists has with pelvic exams.

I suppose some physicians will try to argue that rectal exams are not unpleasant or uncomfortable for the patient, as many did in the comments section of my pelvic exam post. However, if you really believe that, it's probably been a while since your last rectal exam.

The Screening Process

There are two parts to prostate screening: the digital rectal exam (DRE) and the prostate-specific antigen (PSA) blood test. Guided by evidence, here's a look at harms and benefits.

First, is the index finger so sensitive and accurate that it can really detect cancer with the DRE? A little common sense would tell us "no chance," and the evidence seems to support that.

In a study published in the Annals of Surgical Oncology by Richie et al., among 644 asymptomatic men, 241 had an abnormal DRE or elevated PSA. And of the 163 who underwent further ultrasound or biopsy, 77% were found to have normal results.

A retrospective analysis of 14 studies by Hoogendam et al. suggested that the positive predictive value of the DRE was only 28% (95% CI 0.20-0.36), meaning that out of 100 men who were diagnosed by their physician's finger, 72 did not actually have cancer. Plus, according to an analysis by Collins et al., 25% of the time when cancer was found after DRE, the biopsy located it in a different part of the prostate!

So unless your patient has a fecal impaction there is probably very little reason to perform a DRE.

What about the PSA blood test? Its accuracy is also riddled with way too many false positives and false negatives. This is one of those tests that has led to serious rates of overdiagnosis.

Only about 24% of those who undergo prostate biopsy because of elevated PSA actually have prostate cancer (Studer and Collette). The study included 162,243 men, and about 76% of those with a PSA over 3 ng/mL were false positives.

In a study published in the Journal of the National Cancer Institute, which reported the results of The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, Andriole et al. found barely any benefit with PSA screening and DRE. The cumulative mortality rates in the intervention arm were 3.7 compared to 3.4 per 10,000 person-years in the control arm.

Authors of the European Randomized Study of Screening for Prostate Cancer (ERSPC) found a 20% reduction in prostate cancer deaths with PSA. Yet, when you look at actual numbers, it paints a much different picture. The ERSPC study estimated that 1,410 men would need to undergo screening, and 48 more cases of prostate cancer would need to be treated, for one life to be saved. Meaning 48 men will possibly endure erectile dysfunction or urinary incontinence for life, for every one life saved.

When the USPSTF looked at the evidence, they found for every 1,000 men screened for 10 years, roughly 220 had a positive result. About 110 subsequently get a true diagnosis of prostate cancer, 50 get a complication from treatment, and at most one life is saved.

I'll repeat the most important part of that rant: one out of a thousand is saved! At least 50 men will have a serious complication and about 100 will have to undergo anxiety and sleepless nights for a disease they don't even have.

Just under half of those in a different study with a positive screen and negative biopsy, 40%, admitted to worrying about prostate cancer "a lot" or "some of the time." This could qualify as harmful to a man's mental health.

Better Left Unchecked

Finally, in an estimate by Draisma et al., almost 50% of those diagnosed with prostate cancer would have never developed any symptoms of disease had they been left unchecked. Too often people will argue a 10 to 12 years' increase in survival with those screened for prostate cancer.

The problem is the very small or almost nonsignificant increase in mortality. I do not care if my patient survives longer with a disease, as long as the age of mortality remains the same.

After all, the reason we treat hypertension, high cholesterol, or screen for cancer is to have people live longer; not to die at the same age.

Of course, there are physicians out there with anecdotal evidence of catching life-threatening prostate cancer in early stages during a routine DRE or PSA, and will therefore insist they are great tests, just like the pelvic exam.

What shouldn't be forgotten is all of the men who now wear a diaper, can't get an erection, or can't sleep from high anxiety.

So why even have the test available? Possibly if the patient has a positive family history. It seems to increase the patient's risk two or three times above the standard rate of incidence, according to Whittemore et al.

Thus, instead of one out of 1,000, it is 2.5 out of 1,000. At that point, it might be worth at least a conversation. It is also decent to trend the success of prostate cancer treatment. However, as a screening tool it's like swimming with a shark: rarely will it kill you, but it will likely to leave you mentally or physically scarred, feeling vulnerable, and with high anxiety.

Tomado de: Medpagetoday.com  By Andrew Buelt, DO