MRI-guided targeted biopsy reduced overdiagnosis of prostate cancer

Compared to routine biopsy, MRI-guided targeted biopsy reduces the risk of overdiagnosis of prostate cancer in men with elevated levels of prostate-specific antigen, the researchers said.

Jonas Hugosson, MD, Ph.D., and his colleagues wrote in The New England Journal of Medicine that “screening for prostate cancer is plagued by a high rate of overdiagnosis” and that “the most appropriate algorithm for population screening is unknown”.

Currently, a high proportion of prostate cancer cases represent small, usually harmless tumours, the researchers said in a press release, meaning many men could be treated unnecessarily and face the risk of permanent complications.

“We need to move away from blind tissue sampling that is still standard today, and rely on MRI scanning, and thus move from diagnosis to taking samples only from men in whom the MRI imaged tumors – and then only do targeted samples in the area involved,” Hugosson said in the statement.

Hugosson and his colleagues invited nearly 38,000 men between the ages of 50 and 60 for regular prostate-specific antigen (PSA) blood tests. A total of 17,980 (47%) participated in the trial.

Participants who had a PSA level of 3 ng per milliliter or higher underwent prostate MRI. They were then divided into two groups: reference and experimental.

All participants in the reference group who also had elevated PSA levels underwent the standard strategy of systematic tissue sampling. Twelve blind tissue samples were taken from parts of the prostate, and more targeted tissue samples were taken if the MRI showed anything suspicious.

For the participants in the experimental group, the researchers performed a targeted MRI biopsy and took four targeted samples.

Although harmful cancers were found on a similar scale in both groups, the risk of finding harmless cancer was halved in the experimental group.

Of the nearly 11,986 men in the experimental group, 66, or 0.6%, were diagnosed with prostate cancer. In the reference group, 72 of 5,994 participants, or 1.2%, were diagnosed, “a difference of 0.7 percentage points (95% CI, 1.0 to 0.4; RR, 0. 46, 95% CI, 0.33 to 0.64; P < 0.001). »

For clinically significant prostate cancer, the RR in the experimental group compared to the reference group was 0.81 (95% CI, 0.60 to 1.1).

“The results of this study may pave the way for the introduction of general screening for prostate cancer,” Hugosson said in the statement. “But the assessment should also include other factors, such as cost and access to MRI scans.”

The researchers noted that about one in five clinically significant cancers went undetected in the experimental group.

They concluded that using an MRI-guided targeted biopsy instead of routine biopsy for screening and early detection in people with elevated PSA levels “halves the risk of overdiagnosis at the cost of delaying detection of intermediate-risk tumors in a small proportion of patients. ”

“This strategy dramatically reduces the number of people who need to undergo tissue removal, which is an unpleasant procedure with an associated risk of infection. In addition, the strategy halves the risk of detecting a harmless tumor, which has been the greatest obstacle to the introduction of general screening for prostate cancer,” Hugosson said in the statement.

In an accompanying editorial, Roman Gulati, MS, of the Fred Hutchinson Cancer Research Center in Seattle, wrote that “whether the trade-offs of omitting routine biopsy are acceptable must be weighed by the clinical community in the context of contemporary standards of care”.

“The history of PSA screening has shown us that difficult trade-offs between too much and too little diagnosis are inevitable,” Gulati wrote. “There is now a need to determine whether more acceptable trade-offs can be achieved with the use of variables available before diagnosis, such as triage tests or targeted MRI biopsy, or after diagnosis, such as cancer relabeling of clinically insignificant prostate. or using appropriate prudent management.

References: