medwireNews: A population-based, screening-by-invitation trial has demonstrated that a combined MRI-guided plus standard biopsy approach is noninferior to standard biopsy with regard to the detection of clinically significant prostate cancer in men with increased prostate-specific antigen (PSA) levels.
The MRI-based approach was also associated with “markedly reduced incidences of unnecessary biopsy and diagnosis of clinically insignificant cancer,” which “address key barriers impeding implementation of population-based screening for prostate cancer,” write the researchers in The New England Journal of Medicine.
They continue: “The reduced biopsy rate and potential downstream savings that result from less overtreatment offer potential cost savings that may offset the additional costs of MRI.”
Martin Eklund (Karolinska Institutet, Stockholm, Sweden) and co-investigators invited 49,118 male residents of Stockholm county aged 50–74 years to participate in the STHLM3–MRI trial, 12,750 of whom consented to screening.
In all, 1532 men had an elevated PSA level of at least 3 ng/mL and 929 of these men were randomly assigned to undergo an MRI followed by a targeted biopsy of up to three clinically significant lesions, as indicated by a score of 3–5 on the Prostate Imaging Reporting and Data System. This was immediately followed by a standard 10–12 core ultrasound-guided biopsy. The remaining 603 men with elevated PSA had a standard biopsy alone.
In the intention-to-treat analysis, 21% of men screened by the MRI-based approach were diagnosed with clinically significant prostate cancer, defined as a Gleason score of at least 3+4, as were 18% of those who had a standard biopsy, equating to a between-group difference of 3 percentage points.
“Since the lower boundary of the two-sided 95% confidence interval was greater than −4 percentage points, the experimental strategy was deemed noninferior to the standard strategy for detecting clinically significant cancer,” say Eklund and colleagues.
The MRI-based approach was also associated with a significantly lower rate of diagnosis of clinically insignificant prostate cancer (4 vs 12%) or benign disease (11 vs 43%) than the standard approach.
And as men in the MRI group were spared biopsies in the absence of clinically significant lesions on MRI, except if they had a high-risk Stockholm3 test score (≥25%), the proportion of men undergoing biopsies was also lower in the MRI than control group, at 36% versus 73%, report the study authors.
“When normalized to a population of 10,000 men 50 to 74 years of age in which those with elevated PSA levels […] are referred for biopsy, the combined biopsy approach in men with positive MRI scans would result in 409 fewer men undergoing biopsy, 366 fewer biopsies with benign findings, and 88 fewer clinically insignificant cancers detected than with the standard biopsy approach,” they summarize.
“These numbers represent 48%, 73%, and 62% lower incidences, respectively, with the use of MRI and the combined biopsy approach.”
Eklund et al note, however, that if the additional standard biopsy had been omitted in the MRI group, 30 clinically significant cancers would have been missed, the rate of detection would have dropped to 17%, and the criterion for noninferiority would no longer be met.
“Our results therefore support the use of standard biopsy in addition to targeted biopsy for men who have positive MRI results, an observation that is in line with previous findings,” they write.
These findings were simultaneously presented at the 36th Annual European Association of Urology Congress.
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N Engl J Med 2021; doi:10.1056/NEJMoa2100852
EAU 2021; 8–12 July