MRI-Directed Biopsy Can Reduce Prostate Cancer Overdiagnosis

Population-based prostate cancer screening using an MRI-directed targeted biopsy in men with an elevated prostate specific antigen (PSA) level reduced the risk for overdiagnosis by half, according to a new study in New England Journal of Medicine. This reduction occurred at the cost of delayed detection of intermediate-risk tumors in a small proportion of patients.

Jonas Hugosson, MD, PhD, and colleagues of Sahlgrenska University Hospital–Sahlgrenska Academy at Gothenburg University, conducted this population-based screening study by inviting 37,887 men aged 50 to 60 to undergo regular PSA screening. Of these, about half (47%) participated in the trial.

Participants with a PSA of 3 ng/mL or greater underwent MRI of the prostate. One-third of these patients were randomly assigned to a reference group, undergoing systematic biopsy and targeted biopsy of suspicious lesions, and the remaining two-thirds were assigned to an experimental group, undergoing MRI-targeted biopsy alone.

“Targeted biopsy of suspected lesions that are shown on MRI has been suggested as a means of reducing overdiagnosis of prostate cancer; this approach has been shown to be noninferior to systematic biopsy in patients with elevated PSA,” the researchers wrote. “However, there is not a worldwide consensus as to whether systematic biopsy can be omitted.”

In the experimental group, 0.6% of the 11,986 participants were diagnosed with a clinically insignificant prostate cancer compared with 1.2% of the 5,994 participants in the reference group (relative risk=0.46; 95% CI, 0.33-0.64;P<.001). Clinically significant cancer was found in 0.9% of patients in the experimental group compared with 1.1% of those in the reference group (relative risk=0.81; 95% CI, 0.60-1.10).

Clinically significant prostate cancer detected by systematic biopsy only occurred in 10 participants in the reference group. All of these cases were intermediate in risk and were mainly low-volume disease managed with active surveillance.

By changing the diagnostic algorithm to include prebiopsy MRI in all participants with elevated PSA, the researchers showed that risk of detecting Gleason 3+3 cancers would be reduced by half. This is an important finding, the researchers wrote, “since the frequent detection of small Gleason 3+3 cancers after PSA screening is regarded as a major contributor to the high incidence of potentially harmful overdiagnosis of prostate cancer.”

Alternative screening strategies, including transperitoneal and transrectal, are currently undergoing clinical investigation.

Reference

Prostate Cancer Screening With PSA and MRI Followed by Targeted Biopsy Only