Stockholm3 offers a promising avenue for personalised risk-based prostate cancer diagnosis
Dr Scott Eggener - The University of Chicago, Chicago, USA
The study I presented yesterday on behalf of a large team is called SEPTA which is the evaluation of a blood-based biomarker called Stockholm3 which is being used to evaluate men regarding their risk for prostate cancer. It was taken from over 2,000 men prior to a prostate biopsy and measured the operating characteristics on how well it identified grade group 2 prostate cancer or higher and also looking at whether it could be used to minimise the number of men who ultimately need a biopsy.
What was the study design?
There were over 900 men from 17 US and Canadian sites that were prospectively enrolled prior to a prostate biopsy. That was augmented with over 1,200 men with biobank blood and well-annotated clinical and pathologic criteria. In this group of men we’re very proud of the enrichment for racial and ethnic minorities. We overpopulated with folks that were Asian, Hispanic and Black to see how the test worked in those populations.
The primary endpoint was identification of grade group 2 or higher in comparison to a PSA threshold of greater than 4.0. We looked at the Stockholm3 performance when the Stockholm3 was greater than 15.
What were the results?
The results were set up to compare the relative sensitivity of Stockholm3 versus PSA. The relative sensitivity was comparable, slightly less, meaning picking up slightly less grade group 2 or higher. But, really importantly, the specificity of the test was way higher, it was over 50% specificity, meaning anywhere from 40-50% of men would not have needed to undergo a biopsy if they used the Stockholm 3 test in lieu of a standard cut point of PSA greater than 4.0.
How can this improve treatment and diagnosis?
The intent of screening in prostate cancer is to identify grade group 2 or higher and then determine management based on that. But there are still millions of men the world over who undergo biopsies that do not show cancer or show grade group 1 that we monitor. So integrating this test, which I would consider a secondary biomarker after PSA, is really attractive because it captures nearly all the men with grade group 2 or higher while simultaneously limiting the number of men that need to undergo a biopsy. So biopsies are uncomfortable, there’s a relatively low level of risk but oftentimes they do not show cancer or show the type of cancer grade group 1 that we’re not really trying to find and can unnecessarily torture men.
So it's a really attractive test. It has been used and extensively validated in Sweden and is commercially available there. Based on these results we’re hoping it will be available in the US at some point this upcoming year.
What’s next for this study?
It’s a great question. There are ongoing tests being planned to further evaluate the test characteristics and the populations and further validate and also provide additional data for clinicians and patients to hopefully support its integration and further use.