MRI-guided screening limits prostate cancer overdiagnosis

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,according to findings from the STHLM3-MRI trial presented at the 2021 European Association of Urology Annual Congress and simultaneously published in the New England Journal of Medicine.¹

"Our results from a large, randomized study show that modern methods for prostate cancer screening maintain the benefits of screening, while decreasing the harms substantially. This addresses the greatest barrier to the introduction of nationwide screening," study investigator Tobias Nordström, MD, PhD, associate professor of Urology at the Department of Clinical Sciences, Danderyd Hospital at Karolinska Institutet, stated in a press release.²

The STHLM3-MRI study was a prospective, randomized, trial in men aged 50 to 74 from the general population 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 1532 of 12,750 men who enrolled had a PSA ≥3 ng/mL and were randomized to the standard group (n = 603) or the MRI group (n = 929). The primary end point of the trial was the proportion of patients in the intention-to-treat population who were diagnosed with clinically significant prostate cancer, defined as (Gleason score ≥7).

The results showed that only 4% (n = 41) of the MRI group was diagnosed with clinically insignificant cancers, compared with 12% (n = 73) of the standard group. Further, 21% (n = 192) of the MRI group and 18% (n = 106) of the standard group were diagnosed with clinically significant cancer, demonstrating noninferiority for the MRI approach (P <.001).

"Refined screening methods are required to reduce overdiagnosis and overtreatment of low-risk tumors and prevent unnecessary biopsies and biopsy-related side effects," study investigator Martin Eklund, PhD, associate professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, stated in the press release.

Regarding next steps, Nordström stated, “We will soon present the second of the two main reports from the STHLM3MRI trial where we assess the role of a novel blood test as adjunct to MRI in prostate cancer screening. The future of prostate cancer diagnostics probably includes both improved blood tests and MRI. Nationwide screening for breast and cervical cancer among women has been available in the Western world for some time. We are finally able to show that men can also reduce their risk of malignant cancer through nationwide prostate-cancer screening that utilizes modern methods."

References

1. Eklund M, Jäderling F, Discacciati A, et al. MRI-Targeted or Standard Biopsy in Prostate Cancer Screening [published online ahead of print July 9, 2021]. N Engl J Med. doi: 10.1056/NEJMoa2100852.

2. MRI can cut overdiagnoses in prostate-cancer screening by half. Published online July 9, 2021. Accessed July 15, 2021. https://bit.ly/3yVp1Ba.