PIRADS 2 has some radiological problems. Firstly, there is only moderate agreement among readers with this version. Additionally, PIRADS 2 has limited performance in Gleason score 4+3 lesion when its volume is less than 0.5 ml. There is also some subjective descriptors incorporated into the system and the 1.5 cm cutoff between PIRADS 4 and PIRADS 5 is problematic.
Clinical problematic issues also exist with PIRADS 2. It still does not tell us when it is best to biopsy lesions, it is difficult to distinguish PIRADS 3 from PIRADS 4 in the peripheral zone (PZ), and lastly, the incorporation of PIRADS in the community urologists and radiologists is not optimistic. Clinical parameters such as PSA and other biomarkers are still not well incorporated to the PIRDAS system in the “real world” practice. Studies have actually shown that the addition of the urine prostate cancer biomarker PCA3 to PIRADS 3 lesions resulted in an increased accuracy up to 91.2%. Additionally, when incorporating PSA density to PIRADS scores, this too, caused an increase in the detection rate of clinically significant prostate cancers.
What should the future PIRADS ver. 3 include to make it better? Firstly, all descriptors should be objective and not subjective, secondly, all descriptors with constant low percentage of agreement should be removed, and thirdly, quality assurance including audits and multidisciplinary review of outcomes should be incorporated on a regular basis. Additional changes should include a much clearer difference between PIRADS 3 and 4 lesions, and validation of the cutoff lesion size of 1.5 cm must be performed. Lastly, mentored reading for the novice reader should be conducted and education must be standardized. PIRADS ver. 3 should also include more clinical parameters and incorporate PSA density and PCA 3 tests. Additionally, creation of practical nomograms incorporating radiologic variables should improve the scoring accuracy and make it easier to adopt.
In summary, both PIRADS versions to date have equivalent accuracy but version 2 has moderate inter-observer agreement. PIRADS 2 is a growing document with several problems including subjective descriptors, needing to have moderate experience to fully and accurately implement it and a hazy cutoff between PIRADS 3 and 4. PIRADS ver. 3 should be created in an attempt to solve all these issues.
Speaker(s): Thomas James Polascik, Durham (US)
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto
at the #EAU17 - March 24-28, 2017- London, England