mpMRI based targeted biopsy of the prostate: Is there a preferred technique?

Abstract

Part III: Outcomes of the FUTURE trial In chapter 5 the primary outcomes of the FUTURE trial are presented. Among the 665 recruited patients, 234 (35%) had PIRADS≥3 lesions on mpMRI and were randomised for subsequent mpMRI based TB (79 for FUS-TB, 78 for COG-TB, and 77 for MRI-TB). There were no significant differences in baseline characteristics or mpMRI outcomes among the groups. Overall 115 cases of prostate cancer (49%) and 78 cases of clinically significant prostate cancer (33%) (Gleason score ≥3+4 (ISUP grade ≥2)) cases were detected using TB. We demonstrated that there are no statistically significant differences in the overall detection rates of prostate cancer among three techniques of mpMRI based TB (FUS-TB 49%, COG-TB 44%, MRI-TB 55%, p=0.4). Furthermore, no significant differences have been found in the detection rates of clinically significant prostate cancer among the techniques (FUS-TB 34%, COG-TB 33%, MRI-TB 33%, p>0.9). Finally, pre-specified sub-analysis did not demonstrate statistically significant differences in (clinically significant) prostate cancer detection rates between the techniques in various subgroups of patients. The study was, however, hampered by a lower yield of PIRADS≥3 on mpMRI than predicted and thus low availability of TB, causing under-powering for the primary endpoint. Thus, these results should be considered with caution.

Chapter 6 presents a secondary analysis of the FUTURE trial, in which the yield of mpMRI based TB was compared with the yield of repeated TRUS-SB. In a FUTURE trial cohort of 152 patients that underwent both TB and SB, we demonstrated that TB detected significantly more prostate cancer than SB (47% vs 32%, p<0.001). The combination of TB and SB detected prostate cancer in 53% cases, representing a prostate cancer detection rate difference of 6% compared with TB alone. Furthermore, TB detected significantly more clinically significant prostate cancer (34% vs 16%, p<0.001) and less clinically insignificant prostate cancer (13% vs 16%, p=0.4) than SB. The combination of TB and SB detected clinically significant prostate cancer in 35% cases (representing a detection rate difference of 1% compared with TB alone) and detected clinically insignificant prostate cancer in 18% cases (representing a detection rate difference of 5% compared with TB alone). In other words, had repeated TRUS-SB been omitted in these patients, only 1% of clinically significant prostate cancer would have been missed. Simultaneously, omitting TRUS-SB in these patients would have resulted in 5% less detected clinically insignificant prostate cancer. Finally, the Gleason score concordance of radical prostatectomy (RP) and TB was higher than the Gleason score concordance of RP and SB. Therefore, the additional value of repeated TRUS-SB in patients undergoing TB in a repeat biopsy setting is limited, and should not be performed.