In a Swedish population-based noninferiority trial (STHLM3-MRI) reported in The New England Journal of Medicine, Eklund et al found magnetic resonance imaging (MRI)-targeted biopsy was noninferior to standard biopsy in detecting clinically significant cancers in men with elevated prostate-specific antigen (PSA) levels.
As stated by the investigators, “High rates of overdiagnosis are a critical barrier to organized prostate cancer screening. MRI with targeted biopsy has shown the potential to address this challenge, but the implications of its use in the context of organized prostate cancer screening are unknown.”
Study Details
In the trial, 49,118 men from Stockholm County aged 50 to 74 years were invited by mail to undergo screening, with 12,750 consenting and providing blood samples. Of these, 1,532 with PSA levels ≥ 3 ng/mL were randomly assigned 2:3 between February 2018 and March 2020 to undergo standard biopsy (n = 603) or MRI with targeted and standard biopsy if MRI results were suggestive of prostate cancer (n = 929). The primary outcome measure was the proportion of men with a diagnosis of clinically significant cancer, defined as Gleason score ≥ 7, in the intention-to-treat population. Noninferiority in the MRI-directed biopsy group was achieved if the lower bound of the two-sided 95% confidence interval (CI) was > −4%.
Key Findings
Clinically significant cancer was diagnosed in 192 (21%) of 929 men in the MRI-directed biopsy group vs 106 (18%) of 603 in the standard-biopsy group (difference = 3%, 95% CI = −1% to 7%, P < .001 for noninferiority).
Clinically insignificant cancer, defined as a Gleason score of 6, was diagnosed in 41 patients in the MRI-directed group vs 73 (12%) in the standard-biopsy group (difference = −8%, 95% CI = −11% to −5%).
Biopsy findings were benign in 105 patients (11%) in the MRI-directed group vs 259 (43%) in the standard-biopsy group (difference = −32%, 95% CI = −36% to −27%).
Infections after biopsy that were treated with antibiotics occurred in 2% vs 4% of patients (difference = −2%, 95% CI = −4% to 0.1%). Hospitalization occurred for 1% vs 3% (difference = −1%, 95% CI = −3% to 0.1%). No deaths were reported in either group.
The investigators concluded, “MRI with targeted and standard biopsy in men with MRI results suggestive of prostate cancer was noninferior to standard biopsy for detecting clinically significant prostate cancer in a population-based screening-by-invitation trial and resulted in less detection of clinically insignificant cancer.”
Disclosure: The study was funded by the Swedish Research Council and others. For full disclosures of the study authors, visit nejm.org.
