THE PROMIS STUDY: DIAGNOSTIC ACCURACY OF MRI AND TRUS BIOPSY IN PROSTATE CANCER


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Louise Brown1,Hashim Ahmed2,Ahmed El-Shater Bosaily2,Gabe Rhian3,Kaplan Richard1,Yolanda Collaco-Moraes1,Katie Ward1,Richard Hindley4,Alex Freeman5,Alex Kirkham5,Robert Oldroyd6,Chris Parker7,Mark Emberton2,The PROMIS Study Group8
1MRC Clinical Trials Unit at UCL,2University College London,3University of York,4Hampshire Hospitals NHS Foundation Trust,5University College London Hospital NHS Foundation Trust,6Patient and Public Representative,7Royal Marsden Hospital,8PROMIS Collaborators

Abstract

Background

Multi-parametric magnetic resonance imaging (MP-MRI) used as a triage test might allow men to avoid unnecessary transrectal ultrasound-guided prostate biopsy (TRUS-biopsy).

Method

The PROMIS Study (ClinicalTrials.gov/NCT01292291) was a multicenter, paired-cohort, confirmatory study testing MP-MRI and TRUS-biopsy against an accurate reference test - template prostate mapping biopsy (TPM-biopsy). Men with an elevated PSA up to 15ng/ml with no prior biopsy underwent MP-MRI followed by TRUS-biopsy and TPM-biopsy. The conduct and reporting of each test was performed blind to other test results. Clinically significant cancer was defined as Gleason >/=4+3 and/or a maximum cancer core length >/=6mm.

Results

Between May 2012 and December 2015, 576 men underwent all 3 tests. On TPM-biopsy 408/576 (71%) had cancer with 230/576 (40%) being clinically significant. For MP-MRI, the sensitivity for clinically significant cancer was 93%[95%CI 88-96], specificity 41%[36-46], positive predictive value 51%[46-56] and negative predictive value 89%[83-94]. TRUS-biopsy was significantly less sensitive than MP-MRI (48%[42-55], p<0.0001). Two alternative scenarios were compared against the current practice standard of TRUS-biopsy. First, using MP-MRI as a triage test would avoid primary biopsy in 158/576 (27%), but miss 14/576 (2%) cases of clinically significant cancer. Second, if targeted biopsy based on the MP-MRI were to match the accuracy of TPM-biopsy, triage with MP-MRI would avoid biopsy in 158/576 (27%) but detect an additional 17/576 (3%) clinically significant cancers.

Conclusion

MP-MRI, as a triage test prior to first biopsy, can identify a quarter of men who might safely avoid an unnecessary biopsy and correctly identify over 90% of men with clinically significant cancer.

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