Why the Scandinavian prostate cancer study doesn’t translate to the U.S.

by Richard Hoffman, MD, MPH, FACP

Lots of news coverage about a Scandinavian prostate cancer study.  Here’s a guest post on the study from Richard M. Hoffman, MD, MPH, Professor of Medicine at the University of New Mexico School of Medicine, and Staff Physician in the New Mexico VA Health Care System.  He has done story reviews and written blog posts on this site in the past. He has worked to develop shared decision making tools for prostate cancer screening and treatment of localized prostate cancer.

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This week the 23-year follow up data from the Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) was published in the New England Journal of Medicine.  The landmark SPCG-4 study was the first to show that men with localized cancers (confined to the prostate) had a survival benefit if they underwent radical prostatectomy surgery compared to watchful waiting (no active treatment).  Study results, first published in 2002, have consistently shown that the surgical group had a lower risk for dying from prostate cancer and developing metastatic disease than the watchful waiting group, and the most recent report also showed a lower risk for death from any cause.

For me, the study raises 2 important issues relevant to prostate cancer in the United States.  The first point is that PSA screening became widespread in the US in the early 1990s—a decade before the first SPCG-4 publication.   Perversely, the American way was to expend considerable resources to promote screening efforts to find cancers…before knowing whether these cancers could be successfully treated.  The second point is that the SPCG-4 results are not readily translatable to US practice.  Only 5% of the study cohort had cancers detected by screening PSA—the rest either had symptoms and/or a palpable tumor.  In the US, a substantial proportion of men with PSA-detected cancers have microscopic disease—which may never cause problems during a man’s lifetime.  The US Prostate Cancer Versus Observation Trial (PIVOT) also evaluated surgery vs. watchful waiting.  However, PIVOT, which mostly enrolled men with PSA-detected cancers, found no benefit for surgery.   Post-hoc analyses suggested that only the small proportion of men with higher-risk cancers (based on PSA and the microscopic appearance of the cancer) seemed to have a survival benefit.  This suggests that most men with PSA-detected cancers—the great majority of whom undergo aggressive treatment–will experience only the potential harms of treatment without any expectation of experiencing a prostate-cancer survival benefit.

Although the U.S. Preventive Services Task Force has advised against performing PSA testing, hundreds of thousands of men are still being diagnosed each year with prostate cancer.  These men need to be aware that early detection and aggressive treatment might not be good for their health, particularly for men with low-risk microscopic cancers.  These men should consider strategies such as active surveillance (AS).  With AS, men are closely monitored and offered aggressive treatment only if there is evidence that cancer is progressing—which we now know from the SPCG-4 and PIVOT trials is when treatment is most likely to be beneficial.

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Publisher’s note:

A web search turns up some really unhelpful and misleading headlines on this study, such as:

Stories in the Boston Globe, CNN.com, the Associated Press and the Los Angeles Times each included at least some semblance of caveats or independent assessment of the findings, although the latter’s headline – “Surgery reduced risk of death by 44% in men with prostate cancer” – simply wasn’t helpful.

Some headlines – like the Globe’s “Study fuels prostate cancer debate” – followed the mammography-trial-du-jour framing of “conflicting, confusing” results.  Read beyond the headlines and you’ll see why that’s unhelpful for public comprehension.

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Comments (5)

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David Miller

March 6, 2014 at 10:20 am

Define a “low risk” cancer for me. Define “low-risk microscopic cancer” if that indeed is a separate term.

Also, would it be better for a guy to find out he has prostate cancer before or after it became metastatic?

    Gary Schwitzer

    March 6, 2014 at 2:21 pm

    The American Urological Association defines low-risk prostate cancer as:

    Low risk: PSA “10 ng/mL and a Gleason score of 6 or less and clinical stage T1c or T2a

    A National Cancer Institute article states:

    The Johns Hopkins definition of very-low-risk prostate cancer is similar to the National Comprehensive Cancer Network definition. For the study in JCO, very-low-risk was defined as:

    Clinical stage T1c (no palpable disease, biopsy recommended based on abnormal PSA)
    Gleason score of 6 or less
    PSA density (ratio of PSA level to prostate gland size) of 0.15 ng/mL or less
    Two or fewer biopsy cores in which cancer is present, and less than 50 percent cancer present in any involved core

    A simple web search will lead you to much discussion about stratifying risk for prostate cancer.