Novel blood test plus MRI-targeted biopsy shows promise for prostate-cancer screening

Reuters Health - 20/08/2021 - A prostate-cancer-screening strategy combining the Stockholm3 test with MRI-targeted biopsy reduced prostate cancer deaths while substantially reducing over-diagnosis, biopsy rates and MRI procedures, compared with a traditional screening approach, in the Swedish STHLM3-MRI study.

Developed at the Karolinska Institutet in Stockholm, the Stockholm3 test combines clinical information, protein measurements (including prostate-specific antigen, or PSA) and a genetic score based on single-nucleotide polymorphisms to estimate risk.

In the STHLM3-MRI study, more than 49,000 men aged 50 to 74 years were invited by mail to participate; 12,750 accepted and provided blood samples and relevant information for the Stockholm3 test.

A total of 2,293 men found to be at increased risk for prostate cancer - defined as either a PSA of 3 ng/mL or higher or a Stockholm3 score of 0.11 or higher - were randomly allocated to traditional PSA testing and systematic prostate biopsies (standard group) or the Stockholm3 test coupled with MRI-targeted biopsies (experimental group).

They compared the sensitivity of a Stockholm3 of 0.11 or higher with a PSA of 3 ng/mL or higher to detect clinically significant prostate cancer (defined as a Gleason score of 7 or higher).

The area under the receiver-operating characteristic curve for detection of clinically significant prostate cancer was 0.76 (95% confidence interval, 0.72 to 0.80) for the Stockholm3 test compared with 0.60 (95% CI, 0.54 to 0.65) for PSA.

A Stockholm3 threshold of 0.15 or higher had the same sensitivity to detect clinically significant prostate cancer when compared with a PSA of 3 ng/mL or higher, while detecting fewer low-grade tumors, fewer MRIs and fewer biopsy procedures, although these differences were not statistically significant.

"The results from this trial show that replacing PSA with the Stockholm3 test in a screening setting, in which MRI and targeted biopsies are used, decreases the number of MRIs done by 36% and biopsy procedures done by 8%, while maintaining the ability to detect clinically significant prostate cancer," report Dr. Tobias Nordstrom of Karolinska Institutet and colleagues in The Lancet Oncology.

In a comment published with the study, Dr. Caroline Moore of University College London says the STHLM3-MRI study has shown "the advantages of using Stockholm3 and MRI to identify men who need biopsy over the traditional PSA and standard biopsy approach, both in the initial screening test and the subsequent diagnostic test. Further work will be needed to assess the generalizability and cost-effectiveness of this approach."

The study did not have commercial funding. Some of the authors have pending patents related to prostate-cancer diagnosis and own shares in A3P Biomedical, which collaborates with Karolinska Institutet in developing the technology for the Stockholm3 test.

SOURCE: https://bit.ly/3ggphEd and https://bit.ly/3su6fij The Lancet Oncology, online August 12, 2021.

By Reuters Staff



Posted on 20 August 202124 August 2021