MRI-directed targeted biopsy reduced prostate cancer overdiagnosis

Compared with systematic biopsy, MRI-directed targeted biopsy reduces the risk of overdiagnosis of prostate cancer for men with elevated prostate-specific antigen levels, according to researchers.

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

Currently, a high proportion of prostate cancer cases represent small, typically harmless tumors, the researchers said in a press release, which means that many men could be treated unnecessarily and face the risk of permanent complications.

“We must get away from the blind sampling of tissues that’s still standard today, rely on the MRI examination, and thus switch diagnostics to taking samples only in those men in whom MRI has depicted tumors — and then only do targeted samples in the area involved,” Hugosson said in the release.

Hugosson and colleagues invited nearly 38,000 men aged 50 to 60 years to take 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 a 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 participants in the experimental group, the researchers conducted MRI-targeted biopsy and took four targeted samples.

Though 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%, received a diagnosis of prostate cancer. In the reference group, 72 of the 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 with the reference group was 0.81 (95% CI, 0.60 to 1.1).

“The results from this study can pave the way for the introduction of general screening for prostate cancer,” Hugosson said in the release. “But assessment must include also other factors, such as costs and access to MRI scans.”

The researchers noted that about one in five clinically significant cancers were missed in the experimental group.

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

“This strategy is sharply reducing the number of people who need to undergo tissue sampling, which is an unpleasant procedure with an associated risk of infection. What’s more, the strategy halves the risk of detecting a harmless tumor, which has been the biggest obstacle to introducing general screening for prostate cancer,” Hugosson said in the release.

In an accompanying editorial, Roman Gulati, MS, of the Fred Hutchinson Cancer Research Center in Seattle, wrote that “whether the trade-offs of omitting systematic biopsy are acceptable needs to 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. “A reckoning is now needed with regard to whether more acceptable trade-offs can be achieved with the use of variables that are available before diagnosis, such as triage testing or MRI-targeted biopsy, or after diagnosis, such as relabeling clinically insignificant prostate cancer or using appropriate conservative management.”

References:

• Gulati R, et al. N Engl J Med. 2022;doi:10.1056/NEJMe2214658.
• Hugosson J, et al. N Engl J Med. 2022;doi:10.1056/NEJMoa2209454.
• New prostate cancer diagnostic pathway paves way for general screening. https://www.eurekalert.org/news-releases/973800. Published Dec. 7, 2022. Accessed Dec. 9, 2022.