THE PROMIS STUDY: DIAGNOSTIC ACCURACY OF MRI AND TRUS BIOPSY IN PROSTATE CANCER
Session type: Oral
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).
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.
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.
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.