Does MRI Improve Accuracy of Biopsy in Prostate Cancer Screening?

Increasingly, urologists are using magnetic resonance imaging (MRI) to inform decisions about biopsy in men who undergo prostate-specific antigen (PSA) screening for prostate cancer. Presumably, biopsies targeted to MRI abnormalities — rather than systematic but nontargeted biopsies — could reduce overdiagnosis of clinically insignificant cancers.

This Swedish trial involved 18,000 men (age range, 50–60) who had PSA screening. The 1200 men with PSA levels ≥3 ng/mL underwent MRI and were randomized to two groups. In one group, only MRI-detected abnormalities (seen in ≈40% of participants) were biopsied. In the other group, men underwent both MRI-targeted and standard systematic 12-core biopsies. Key findings were as follows:

• With the overall study population as the denominator, clinically insignificant prostate cancer (i.e., Gleason score, 3+3) was diagnosed significantly less frequently in the MRI-targeted group than in the targeted-plus-systematic biopsy group (0.6% vs. 1.2%). In contrast, clinically significant lesions were found in about 0.9% and 1.1% of patients in the two groups, respectively (a statistically nonsignificant difference).
• With men whose PSA was >3.0 ng/mL as the denominator, significant and insignificant cancers were found in 14% and 8% of men, respectively, in the MRI-targeted group. In contrast, significant and insignificant cancers were found in 17% and 18% of men, respectively, in the targeted-plus-systematic biopsy group.