Prostate News

In Defense of Prostate Cancer Screening

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Davies is writing in response to “More Health Care Is Better Health Care: Medical Myth Or Reality?” by Robert Pearl,  Chief Executive, Permanente Medical Group and a Forbes contributor.

Have you ever asked your plastic surgeon advice on prostate cancer screening? Or the utility of an annual physical exam? Or how to treat that nagging back pain? Of course you haven’t and why would you? Still the CEO of the Permanente Medical Group, the physician group part of Kaiser Permante, Dr. Pearl (a respected plastic and reconstructive surgeon) feels comfortably equipped to comment on these issues and has in his recent Forbes column. As a doctor who specializes in the treatment of prostate cancer patients, I have to object.

“Unfortunately, in most cases, doctors can’t differentiate between cancer that will become harmful and cancer that won’t,” Pearl wrote. “So, when tests suggest the presence of prostate cancer, most men pursue treatment.”

That statement is wrong. The data on prostate cancer screening actually indicate that, when done right, prostate cancer screening does save men’s lives. And prostate cancer is probably the most studied carcinoma in the world when it comes to stratifying patients by the risk of their disease. New diagnostic tests, some of them based on genetics, will allow us to do this in an even better way.

Of course, Pearl isn’t alone in besmirching prostate cancer screening. His essay parrots the findings of the increasingly powerful (and controversial) U.S. Preventative Services Task Force (USPSTF), a group convened by the government that tries to evaluate which treatments and procedures are supported by evidence and which are not. Notably, this group made its decision without an academic urologist, oncologist, or radiation oncologist. It says prostate cancer screening is not warranted based on two big clinical trials; the European Randomized Study of Screening for Prostate Cancer (ERSPC) and the Prostate, Lung, Colorectal, and Ovarian Cancer Study (PLCO). Unfortunately, definitive conclusions were made on incomplete data. For instance, the USPSTF relied on the 9yr outcome data from the ERSPC which is not even close to its pre-specified main follow-up time (the later results showed significant reduction in prostate cancer mortality in the 11 year follow-up data)

The USPSTF is guilty of the sin of omission. It never considered the important work of Dr. Ruth Etzioni at the Fred Hutchinson Cancer Research Center who has used retrospective data to create models that show the large impact screening has had on prostate cancer mortality in the United States. This exact type of complicated statistical modeling was used in the USPSTF breast cancer recommendations. And the USPSTF did not take into account basic prostate cancer epidemiology. Between the years 1994 and 2005 the prostate cancer mortality rates in the US fell about 4% a year and the rates are still declining (for now). There is no plausible explanation for this except for screening. Accordingly there has also been a 40% decrease in the rates of prostate cancer metastasis since screening began – again there is no plausible explanation for this except for screening.

This is a fact: We can differentiate between harmful tumors and slow growing tumors, which means many men can safely not be treated. Hundreds of thousands of men who have slow growing prostate cancers are monitored and not treated here in the US and worldwide. It has been painful to see many urologists reject active surveillance of prostate cancer and treat many men inappropriately. In fact I would posit that as a group we have contributed to the PSA screening conundrum precisely because we failed to promote active surveillance of slow growing prostate cancer tumors.

Our ability to follow slow growing tumors is a product of decades of careful epidemiologic research into the natural history of the disease. Carefully constructed prediction calculators have been made by our leading researchers (called the Partin Tables or CAPRA scores) that can help counsel our patients on their risks of the disease affecting them over time.

I don’t mean to suggest that Pearl and the USPTSF don’t have a point. Many urologists do over-treat low grade prostate cancer tumors in elderly men (or over use androgen deprivation), and this is shameful. I truly believe there will be a day that insurance companies (and medicare) should not pay for treating 80 year olds with low grade, low volume prostate cancer. This is a complicated, fraught, and challenging topic. But I think many critics of screening go much too far without even acknowledging the limitations of the data at hand. To do so is dangerous, intellectually dishonest, and – in my opinion – might shorten the longevity of American men. We need screening, and we can make it better.

 Benjamin Davies is an Associate Professor in the Department of Urology at the University of Pittsburgh School of Medicine. You can follow him on Twitter TWTR +0.49% at @daviesbj.