MRI screening PROMISes reduction of unnecessary prostate biopsies
medwireNews: Using multi-parametric magnetic resonance imaging (MP-MRI) to triage men with a clinical suspicion of prostate cancer could reduce unnecessary biopsies and improve the detection of clinically significant cancer, suggest PROMIS trial findings.
The study evaluated the diagnostic accuracy of MP-MRI and transrectal ultrasound-guided prostate biopsy (TRUS-biopsy), the procedure generally used in men who present with elevated prostate-specific antigen (PSA) levels. The researchers used transperineal template prostate mapping biopsy (TPM-biopsy) as the reference test because it is “able to accurately characterise disease status in men at risk by sampling the entire prostate every 5 mm.”
A total of 576 biopsy-naïve men with PSA levels no higher than 15 ng/mL underwent 1.5 Tesla MP-MRI, followed by both TRUS- and TPM-biopsy, where each test was conducted without knowing the results of the other tests.
TPM-biopsy showed the presence of cancer in 71% of participants, with 40% harboring clinically significant disease, defined as a Gleason score of at least 4 + 3 or a maximum cancer core length of 6 mm or longer.
MP-MRI was significantly more sensitive than TRUS-biopsy for detecting clinically important cancer, at 93% versus 48%, and also had a significantly higher negative predictive value, at 89% and 74%, respectively.
The authors comment: “The high negative predictive value is reassuring in that a negative MP-MRI result implies a high probability of no clinically significant cancer.”
However, the procedure had a significantly lower specificity and positive predictive value than TRUS-biopsy, at 41% versus 96% and 51% versus 90%, respectively, indicating that “a biopsy, with the needles deployed based on the MP-MRI findings, is still needed in those men with a suspicious MP-MRI,” the team writes.
Hashim Ahmed, from University College London in the UK, and co-investigators estimate that using MP-MRI to conduct an initial screen could help 27% of men avoid a primary biopsy and lead to 5% fewer diagnoses of clinically insignificant cancer.
And if MP-MRI were used to guide subsequent TRUS-biopsies, “up to 18% more cases of clinically significant cancer might be detected compared with the standard pathway of TRUS-biopsy for all,” they add.
During the course of the study, 88% of participants reported a side effect, while 6% experienced a serious adverse event, including eight cases of sepsis secondary to urinary tract infection and 58 cases of urinary retention.
Ahmed et al conclude in The Lancet: “Cost-effectiveness analyses of the PROMIS data are underway and will be reported elsewhere, but the primary outcome data provide a strong argument for recommending MP-MRI to all men with an elevated serum PSA before biopsy.”
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