Novel blood-based algorithm outperforms PSA for prostate cancer screening
medwireNews: The Stockholm3 risk prediction tool performs at least as well as prostate-specific antigen (PSA) screening for the detection of clinically significant prostate cancer, research suggests.
Moreover, “the novel strategy of combining the Stockholm3 test and an MRI [magnetic resonance imaging]-targeted biopsy approach is associated with a 69% reduction in the rate of overdetection, while maintaining the sensitivity to detect clinically significant prostate cancer,” write Tobias Nordström (Karolinska Institutet, Stockholm, Sweden) and co-authors in The Lancet Oncology.
The findings are a result of the prospective, population-based STHLM3–MRI study, which has already shown that an MRI-guided plus standard biopsy approach is noninferior to standard biopsy for detecting clinically significant prostate cancer and reduces the detection of clinically insignificant disease.
The current analysis set out to determine whether the Stockholm3 risk prediction test, which combines clinical information, protein measurements (including PSA), and a genetic score based on single nucleotide polymorphisms, can improve the selection of men undergoing MRI.
In all, 49,118 men aged 50–74 years were invited to participate in STHLM3–MRI, 12,750 of whom were enrolled and provided blood samples. Of these, 2293 had an elevated risk for prostate cancer (PSA ≥3.0 ng/mL or Stockholm3 ≥0.11 points) and were randomly assigned to undergo biparametric MRI followed by MRI-targeted and systematic biopsy if MRI positive (n=1372) or to receive systematic prostate biopsies (n=921).
The researchers report that, among those who underwent standard systematic biopsies, screening with Stockholm3 detected clinically significant prostate cancer (Gleason score ≥3 + 4) with greater accuracy than did PSA, with areas under the receiver-operating characteristic curve of 0.76 and 0.60, respectively.
Moreover, in the group that received MRI-targeted biopsies, a Stockholm3 score of at least 0.11 points was noninferior to a PSA of at least 3.0 ng/mL for detection of clinically significant prostate cancer (22.2 vs 20.7%) and also detected a similar number of low-grade (Gleason 3+3) prostate cancers (4.9 vs 4.4%). The proportion of MRIs carried out was almost identical between the two groups (91.2 vs 91.1%) whereas the biopsy rate was slightly higher with a raised Stockholm3 score than with a raised PSA (39.2 vs 36.4%).
The investigators also found that individuals who underwent MRI-targeted biopsies rather than standard systematic biopsies had a significantly lower incidence of antibiotic prescription for infection (1.8 vs 4.4%) and a significantly lower incidence of hospital admission within 30 days of a biopsy (1.2 vs 3.4%).
When the team compared an experimental strategy that combined Stockholm3 risk assessment with MRI-targeted and systematic biopsy (n=7609) with traditional PSA-based screening and systematic biopsies (n=5134) in the entire study cohort, they found that the experimental method resulted in a significantly higher detection rate for clinically significant cancers (3.0 vs 2.1%), significantly lower detection of low-grade cancers (0.7 vs 1.4%), and also led to fewer biopsy procedures (5.3 vs 8.5%).
Nordström and colleagues say their “findings might prompt a re-evaluation of population-based prostate cancer screening in countries with high prostate cancer mortality.”
They add that combining the Stockholm3 test with an MRI-targeted biopsy approach “provides a viable option for prostate cancer screening, in which the mortality benefit of prostate cancer screening is maintained and the overdetection decreased compared with a traditional screening strategy (using PSA and systematic biopsies).”
The team notes that cost-effectiveness analyses of this novel strategy are now underway.
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