Prostate Ca surveillance study has global implications

A new study revealing 91% of very low-risk and 74% of low-risk prostate cancer patients in Sweden choose active surveillance should be a benchmark for the use of the management strategy in the U.S. and elsewhere in the world, according to study authors.

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The fact that such high percentages of prostate cancer patients in all of Sweden are being managed with active surveillance is a huge step forward in reducing prostate cancer overtreatment, according to the study’s lead author, Stacy Loeb, MD, MSc, of New York University Langone Medical Center, New York.

An international team, led by researchers at NYU Langone Medical Center, analyzed data from Sweden’s National Prostate Cancer Register (NPCR) from 2009 through 2014. The NPCR is one of the only national databases in the world with data on 98% of prostate cancers diagnosed in Sweden and extensive links to other nationwide databases. During the study period, 32,518 men were diagnosed with favorable-risk prostate cancer, including nearly 4,700 with very low-risk cancer.

The authors, who published their findings online in JAMA Oncology (Oct. 20, 2016), found that active surveillance increased among Swedish male prostate cancer patients of all ages. Among men with very low-risk cancer, 57% chose active surveillance in 2009 versus 91% in 2014. And while 40% of Swedish men with low-risk cancer chose active surveillance in 2009, 74% chose the option 5 years later. The biggest increase in active surveillance occurred from 2011 and after. 

In a subset of men ages 50 to 59 years, 88% with very-low-risk and 68% with low-risk disease chose active surveillance in 2014. That’s compared to 19% use of active surveillance among those with intermediate-risk disease, representing 17,115 men in the study.

There is no question that active surveillance is also becoming more popular in the U.S. But the most recent numbers demonstrate that most low-risk patients are still getting radical treatment, and that this varies tremendously among practices, Dr. Loeb tells Urology Times.

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“From the perspective of a U.S. urologist, I think the results are very surprising, since the rates of active surveillance are so much lower in the United States,” Dr. Loeb said. “One U.S. study using a registry called CaPSURE reported that 40% of low-risk patients were managed with active surveillance in 2013. However, another recent U.S. study using the National Cancer Database reported much lower rates.”

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Prostate cancer screening reduces metastatic disease and prostate cancer death, but continues to be controversial due to the downstream harms of overdiagnosis of low-risk cancers and subsequent overtreatment with potential side effects.

“In 2012, the United States Preventive Services Task Force recommended against prostate cancer screening, having concluded that the harms outweigh the benefits. However, the main harms that they identified are downstream side effects from prostate cancer treatment, rather than the PSA test itself, which is a simple blood test,” Dr. Loeb said. “The best way to preserve the benefits of screening while reducing harms is to continue early detection of life-threatening cases in time for curative therapy, while avoiding overtreatment of low-risk disease.”

One recent study used a mathematical model to demonstrate that screening is beneficial when low-risk disease is managed with active surveillance, according to Dr. Loeb.

One challenge is to accurately track use of active surveillance in America. U.S. prostate cancer researchers do not have a data source comparable to the Swedish registry, which accounts for virtually every man with prostate cancer in Sweden and includes extremely detailed clinical information, according to Dr. Loeb.

“For example, many U.S. studies do not have enough details to distinguish active surveillance from watchful waiting, or to separate very low-risk versus low-risk prostate cancers,” she said.

In the meantime, Dr. Loeb said the authors of this study hope the findings will encourage American men diagnosed with low-risk prostate cancer to consider active surveillance. This is on the heels of the large ProtecT study that showed no difference in death rates a decade after diagnosis between those who chose active surveillance and those who chose immediate treatment, according to Dr. Loeb.

The next step, she said, is to continue research into the best ways to monitor patients who choose active surveillance.

“In the past, active surveillance involved repeating prostate biopsies as often as once per year. Now, we have several new biomarkers and better imaging, which are noninvasive and will hopefully reduce the number of repeated biopsies,” Dr. Loeb said. “Our research group has a grant to study what is the optimal testing protocol during active surveillance, and also to design new digital resources to help educate and support patients during the surveillance process.”

The Swedish Research Council, Swedish Cancer Society, Laura and Isaac Perlmutter Cancer Center, and Louis Feil Charitable Lead Trust provided funding for this study.

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