MRI screening for prostate cancer prevents many unnecessary biopsies

Reuters Health - 09/07/2021 - Going straight to biopsy after a high PSA reading exposes more cases of clinically insignificant cancer than first using MRI to see if a biopsy is warranted, doctors behind a large Swedish study of 1,532 men are reporting.

The experiment with men age 50 to 74 with PSA levels of at least 3 ng/mL found that when biopsy was done automatically, 18% of the cases were judged to be clinically-significant cancer. When MRI was accompanied by targeted and standard biopsies, the rate was 21% (P<0.001 for noninferiority).

But the rates of clinically insignificant cancers were just 4% with MRI versus 12% with conventional diagnostic care.

"Detection of clinically insignificant tumors and benign findings on biopsy were lower (by 64% and 74% respectively)" with the MRI technique instead of the standard strategy, said the research team, led by Martin Eklund of the Karolinska Institute in Stockholm.

"These results were achieved without compromising detection rates of clinically significant cancers," they said.

The findings of the STHLM3-MRI study, published online by The New England Journal of Medicine and presented at the 36th Annual European Association of Urology Congress, reinforce the idea that men who have a positive MRI test should receive both a targeted biopsy and a standard biopsy.

With a targeted biopsy alone, "detection of 1.7 clinically significant cancers would be delayed for each clinically insignificant cancer avoided," Dr. Eklund and his colleagues said.

The study is part of an attempt to reduce the overdiagnosis of prostate cancer when screening is undertaken.

In the study, 929 men living in Stockholm County, Sweden, were given standard biopsies and 603 were assigned to the experimental group, where testing began with an MRI.

For every 10,000 men in that age group with PSA levels of at least 3, "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," the team concluded.

That, in turn, may cover the added cost of the MRI scans, they said.

A patient was considered to have clinically significant prostate cancer if they had a diagnosis of cancer with a Gleason score of 3+4 or greater.

"The experimental strategy was deemed noninferior to the standard strategy for detecting clinically significant cancer," the researcher said. When the group did a per-protocol analysis, the rates were almost identical - 23% in the experimental group and 24% in the standard biopsy group.

Benign biopsy findings were seen in 11% of the experimental group versus 43% in the standard treatment group.

The rates of infection after the biopsies were 2% in the MRI group and 4% with the conventional regimen, but that difference was not statistically significant.

Hospitalization rates were 1% and 3% respectively.

"Although the MRI-targeted biopsy approach appears to offer important improvements to standard biopsy in the STHLM3-MRI population, longer follow-up would be needed to estimate the effect on mortality," the Eklund team said.

SOURCE: https://bit.ly/3ASFQyK The New England Journal of Medicine, online July 9, 2021.

By Reuters Staff



Posted on 9 July 202119 July 2021