BACKGROUND: Data on the efficacy and safety of screening for prostate cancer with magnetic resonance imaging (MRI) are needed from studies of follow-up screening.

METHODS: In a population-based trial that started in 2015, we invited men who were 50 to 60 years of age to undergo prostate-specific antigen (PSA) screening. Men with a PSA level of 3 ng per milliliter or higher underwent MRI of the prostate. Men were randomly assigned to the systematic biopsy group, in which they underwent systematic biopsy and, if suspicious lesions were found on MRI, targeted biopsy, or the MRI-targeted biopsy group, in which they underwent MRI-targeted biopsy only. At each visit, men were invited for repeat screening 2, 4, or 8 years later, depending on the PSA level. The primary outcome was detection of clinically insignificant (International Society of Urological Pathology [ISUP] grade 1) prostate cancer; detection of clinically significant (ISUP grade =2) cancer was a secondary outcome, and detection of clinically advanced or high-risk (metastatic or ISUP grade 4 or 5) cancer was also assessed.

RESULTS: After a median follow-up of 3.9 years (approximately 26,000 person-years in each group), prostate cancer had been detected in 185 of the 6575 men (2.8%) in the MRI-targeted biopsy group and 298 of the 6578 men (4.5%) in the systematic biopsy group. The relative risk of detecting clinically insignificant cancer in the MRI-targeted biopsy group as compared with the systematic biopsy group was 0.43 (95% confidence interval [CI], 0.32 to 0.57; P<0.001) and was lower at repeat rounds of screening than in the first round (relative risk, 0.25 vs. 0.49); the relative risk of a diagnosis of clinically significant prostate cancer was 0.84 (95% CI, 0.66 to 1.07). The number of advanced or high-risk cancers detected (by screening or as interval cancer) was 15 in the MRI-targeted biopsy group and 23 in the systematic biopsy group (relative risk, 0.65; 95% CI, 0.34 to 1.24). Five severe adverse events occurred (three in the systematic biopsy group and two in the MRI-targeted biopsy group).

CONCLUSIONS: In this trial, omitting biopsy in patients with negative MRI results eliminated more than half of diagnoses of clinically insignificant prostate cancer, and the associated risk of having incurable cancer diagnosed at screening or as interval cancer was very low. (Funded by Karin and Christer Johansson's Foundation and others; GÖTEBORG-2 ISRCTN registry number, ISRCTN94604465.).

Family Medicine (FM)/General Practice (GP) rater

These findings are important. Over-diagnosis in screening can add more costs and risks. A 'negative' MRI without biopsy still detects the most important cancers, but reduces the risk of finding very low grade malignancies. This research is part of the evidence to support new guidelines for improved prostate cancer screening programs.