The PRIME trial has demonstrated that abbreviated biparametric MRI is noninferior to multiparametric MRI for detecting clinically significant prostate cancer, potentially transforming global prostate cancer diagnosis by offering a faster, more cost-effective imaging approach. The findings, published in JAMA, could address critical access barriers that currently limit MRI availability for prostate cancer screening.
Trial Design and Patient Population
The prospective PRIME trial (NCT04571840) enrolled 490 biopsy-naïve men across 22 clinical trial sites in 12 countries. All participants had clinical suspicion of prostate cancer based on rising prostate-specific antigen (PSA) levels and/or abnormal digital rectal examination findings. The median patient age was 65 years (IQR, 59 to 70), with a median PSA level of 5.6 ng/mL (IQR, 4.4 to 8.0).
Both biparametric and multiparametric MRI scans were performed for each patient, followed by targeted biopsy with or without systematic biopsy to confirm diagnostic accuracy. The primary endpoint measured the proportion of men with clinically significant prostate cancer (Gleason grade group 2 or higher), while the secondary endpoint assessed clinically insignificant prostate cancer detection. The non-inferiority margin was set at 5%.
Comparable Detection Rates Achieved
Results showed that biparametric MRI detected clinically significant prostate cancer in 29.2% of patients compared to 29.6% with multiparametric MRI, representing a difference of −0.4 percentage points (95% CI, −1.2 to 0.4; P = .50). For clinically insignificant prostate cancer, detection rates were 9.2% with biparametric MRI versus 9.6% with multiparametric MRI (difference, −0.4; 95% CI, −1.2 to 0.4 percentage points).
Importantly, 99% of scans achieved adequate diagnostic quality according to central quality control analysis, demonstrating the reliability of the abbreviated approach when proper protocols are followed.
Addressing Global Access Barriers
"Currently around 4 million MRI scans are needed each year globally to diagnose prostate cancer. This demand is set to rise rapidly with a predicted surge in prostate cancer cases over the next 20 years," explained principal investigator Veeru Kasivisvanathan, PhD, associate professor at University College London. "Time, cost and staff availability are all limiting factors in how many scans can be offered, which makes the results of the PRIME trial particularly important."
The biparametric approach omits the gadolinium contrast sequence, enabling scans to be completed in up to half the time with fewer staff requirements and reduced costs. This efficiency gain could significantly expand access to prostate MRI, particularly important given that US data show only about one-third of biopsy-naïve men currently receive MRI before biopsy.
Clinical Implementation Considerations
For practicing urologists, the trial results indicate that biparametric MRI can be considered a new standard of care in primary diagnostic settings, provided adequate image quality is maintained and interpretation is performed by skilled radiologists. The omission of contrast did not increase diagnostic uncertainty, alter biopsy recommendations, or meaningfully affect treatment decision-making.
Quality assurance remains critical for successful implementation. In the PRIME trial, centers underwent pre-trial evaluation using the PI-QUAL scoring system, with protocol adjustments made to meet internationally recognized PI-RADS standards. Each center implementing biparametric MRI should assess its imaging quality and ensure interpretation by experienced radiologists.
Future Implications and Research
The authors noted that "provided image quality is adequate, an abbreviated biparametric MRI scan, with or without targeted biopsy, could become the new standard of care for prostate cancer diagnosis. With approximately 4 million prostate MRIs performed globally annually, adopting biparametric MRI could substantially increase scanner throughput and reduce costs worldwide."
Building on these findings, the TRANSFORM trial is set to begin later this year, representing the largest prostate cancer screening trial in 20 years. This study will determine the safest, most accurate, and most cost-effective screening approaches, with results expected to support introduction of a national screening program in the UK.
"The results from the PRIME trial, showing that a faster, cheaper, type of prostate MRI is just as good as the current standard MRI at detecting prostate cancer, [is] a hugely important step in the right direction for making MRIs more efficient," said Matthew Hobbs, PhD, director of research at Prostate Cancer UK.
