Novel blood test enhances prostate cancer screening

Combining the Stockholm3 blood test with MRI-guided prostate biopsy reduced the number of MRIs performed and lowered overdetection, while not sacrificing the capacity to identify clinically significant tumors, according to findings from the STHLM3-MRI study published in the Lancet Oncology.^1,2

Previously shared findings from the STHLM-3MRI study showed that prostate cancer screening with MRI-guided biopsy reduced the detection of clinically insignificant prostate cancer versus use of standard biopsy alone, while also demonstrating noninferiority for detecting clinically significant disease. The new data published in Lancet Oncology show that adding the Stockholm3 test further enhances the positive effect of using MRI-guided biopsy.

“Overall, our studies show that we have identified the tools needed to be able to carry out effective and safe screening for prostate cancer. After many years of debate and research, it feels fantastic to be able to present knowledge that can improve healthcare for men,” study author Tobias Nordström, MD, associate professor of urology at the Department of Clinical Sciences, Danderyd Hospital at Karolinska Institutet, stated in a press release.

The STHLM3-MRI study (NCT03377881) was a prospective, randomized trial in men aged 50 to 74 from the general population who were invited by mail to participate. Blood samples from enrolled patients were then submitted for PSA analysis as well as an assessment by the Stockholm3 blood-test, which was developed by researchers at Karolinska Institutet. Men with PSA levels ≥3 ng/mL were then randomized in a 2:3 ratio to receive standard biopsy or undergo MRI, with targeted and standard biopsy if the MRI results indicated prostate cancer.

Overall, between Feb 5, 2018, and March 4, 2020, 12,750 men enrolled and provided blood specimens. Of these men, 2993 had elevated risk and were randomized to the experimental arm (n = 1372) or the standard arm (n = 921). The data findings published in the Lancet Oncology were for 2 comparisons made by the researchers: Stockholm3 versus PSA in the experimental arm, and PSA plus standard biopsy versus Stockholm3 plus MRI-targeted and systematic biopsy in the overall study population.

The findings showed that, “The area under the receiver-operating characteristic curve for detection of clinically significant prostate cancer was 0.76 for Stockholm3 and 0.60 for PSA,” the authors wrote. Among patients in the experimental arm, a Stockholm3 score of ≥11% was shown to be noninferior to a PSA level of ≥3 ng/mL regarding detection of clinically significant prostate cancer (227 vs 192, respectively) and low-grade prostate cancer (50 vs 41). Stockholm3 was also associated with more MRIs and biopsies. Among patients with Stockholm3 score of ≥15%, Stockholm3 had the same sensitivity as PSA level ≥3 ng/mL, and also resulted in fewer MRIs (545 vs 846) and fewer biopsies (311 vs 338).

Combining a Stockholm3 score of ≥11% with MRI-targeted and systematic biopsies led to a higher detection of clinically significant cancers versus PSA and systemic biopsies (227 vs 106, respectively), reduced detection of low-grade tumors (50 vs 73, respectively), and led to fewer biopsies overall.

“The availability of MRI in healthcare will be a limiting factor. We now show that a novel blood test as adjunct to MRI can reduce the number of MRIs performed by a third. Compared with traditional screening, overdiagnosis is reduced by as much as 69 percent. At the same time, the number of biopsies is halved, while we can find just as many clinically significant tumors,” study author Martin Eklund, PhD, associate professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, stated in the press release.

References

1. New blood test improves prostate cancer screening. Published online August 12, 2021. Accessed August 18, 2021. https://bit.ly/3yV49KS.

2. Nordström T, Discacciati A, Bergman M, et al. Prostate cancer screening using a combination of risk-prediction, MRI, and targeted prostate biopsies (STHLM3-MRI): a prospective, population-based, randomised, open-label, non-inferiority trial [published online ahead of print August 12, 2021]. Lancet Oncol. 2021 doi: 10.1016/S1470-2045(21)00348-X