Background
Men that are suspected to have prostate cancer are generally referred for a standard transrectal ultrasonography-guided prostate biopsy.
This standard biopsy method is linked to under-detection of clinically significant cancers, and over-detection of clinically insignificant cancers. The latter can lead to over-treatment of patients who do not benefit from treatment and can sometimes be adversely affected by treatment side-effects.
Recent advances in multiparametric magnetic resonance imaging (MRI) technology has led to the evaluation of this method as an alternative first-step in the diagnostic pathway for prostate cancer.
This non-invasive tool is proposed as a powerful approach for determining the presence prostate cancer, if the cancer is clinically significant or insignificant, and if considered significant allow for the targeted biopsy of abnormal lesions based on MRI data.
Importantly, it would reduce the number of men undergoing an unnecessary prostate biopsy procedure and facing associated side-effects associated with this intervention.
Aim
PRECISION (Prostate Evaluation for Clinically Important Disease: Sampling Using Image Guidance or Not?) is a multicentre, randomised clinical trial that aimed to evaluate multiparametric MRI as a risk-assessment tool to triage men suspected to have prostate cancer, for or not for, subsequent MRI-targeted biopsy.
Methods
This prospective clinical trial was conducted across 25 centres in 11 countries, recruiting 500 men (mean age 64 years) suspected of prostate cancer, based on a high prostate-specific antigen (PSA) reading or an abnormal digital rectal examination, and no previous history of a prostate biopsy.
Men were randomly assigned at a 1:1 ratio to receive MRI with or without subsequent targeted biopsy (based on MRI result), or standard ultrasonography-guided biopsy.
Subjects in the MRI group who were classified as equivocal, likely or highly likely to have prostate cancer were referred for targeted biopsy.
Diagnoses of clinically significant prostate cancer (Gleason score sum of 7 or higher) or clinically insignificant cancer (Gleason score sum of 6) were measured as primary and secondary outcomes post-biopsy.
Results
Of the patients assigned to the MRI group, more than one-quarter (28%) had an MRI result that did not indicate prostate cancer; therefore those patients did not receive a biopsy.
The remaining 72 per cent of patients had a ‘positive’ MRI result and subsequently underwent a biopsy.
Clinically significant prostate cancer was identified in a higher proportion of patients in the MRI with or without targeted biopsy group (38%; 95/252) compared to the standard biopsy group (26%; 64/248; P<0.01).
Clinically insignificant prostate cancer was identified in fewer patients in the of the MRI-targeted biopsy group (9%; 23/252) than the standard biopsy group (22%; 55/248; P<0.001).
Conclusion
MRI with or without targeted biopsy was found to be superior to standard transrectal ultrasonography-guided biopsy in the detection of clinically significant prostate cancer.
Adoption of MRI screening prior to the decision on whether or not to undergo a biopsy would improve the identification of men with clinically significant cancer who would benefit from treatment.
At the same time this approach would minimise the number of men found to have clinically insignificant cancer who go on to receive unnecessary ‘over-treatment’ of a non-life threatening cancer.
