Multi-parametric magnetic resonance imaging (mp-MRI) fusion targeted biopsy detects more clinically significant prostate cancers (CSPCa) in black men using fewer cores than conventional random biopsy, researchers report.
“These results confirm that MRI/US image fusion targeted prostate biopsy is a useful tool for detecting CSPCa independently to the race,” Toshitaka Shin, MD, of Oita University in Oita, Japan, and colleagues concluded in BJU International, in press.
Black patients tend to present with more advanced prostate cancer (PCa) and have shorter survival times, but the degree to which these differences reflect socioeconomic disparities, biological factors, cultural influences, or some combination, remains unclear.
In a retrospective analysis, the investigators compared results from MRI/US fusion targeted biopsy with conventional random biopsy in 117 black and 544 white men who had pre-biopsy mp-MRI during 2012 to 2015. Radiologists graded mp-MRI findings using the 5-point Likert scale of cancer suspicion, with grade 1 suggesting a very low likelihood of cancer and grade 5 a high likelihood. CSPCa was defined as Gleason score 3+4 and higher at biopsy.
The team found no statistically significant differences in the detection of any PCa between black and white patients using targeted biopsy: 35.0% vs 34.2%. The same held true for CSPCa: 18.8% vs 21.7%, respectively. The investigators adjusted for age, PSA level, and prostate volume. They also considered the results of pre-biopsy imaging and found no substantive differences by race in the location of dominant lesions on mp-MRI and the proportion of patients with Likert grade 5 lesions
Targeted biopsy findings generally coincided with Likert scoring. Targeted biopsy of Likert grade 4-5 lesions performed better than random biopsy in detecting cancer overall (70.6% vs 37.2%) and CSPCa (52.9% vs 12.4%) in black men. The same pattern was observed for white men, according to the investigators.
“Thus, targeted biopsy should be considered for the grade 4-5 lesions,” according to Dr Shin and colleagues. “In contrast, lower scores (grade 1-2) on MRI may be useful in predicting low likelihood of high grade cancer, so targeted biopsy could potentially be avoided. Grade 3 is equivocal and biopsy indication for grade 3 needs to be evaluated in further investigation.”
Targeted fusion biopsy of grade 3 lesions identified any PCa more often in black men (47.6% vs 28.9%, but there no differences by race in detection of CSPCa. A greater proportion of grade 3 lesions in black men could be insignificant cancer, but more research is needed.
Targeted biopsy also provided longer cancer core length than random biopsy (5.0 vs 2.4 mm) and captured more cancer per core (24.9% vs 6.8%). The median number of cores for detecting one patient with CSPCa was 13.3 vs 81.9, respectively.
The investigators mentioned several noteworthy study limitations. Patients were a heterogenous mix of biopsy naïve men, men with prior negative biopsy, and men with prior positive biopsy. Patients without visible lesions on MRI were excluded. Prostate biopsy results may not be as strong as findings from radical prostatectomy specimens.
In addition, the jury is still out on the comparative utilities of the 5-point Likert scale score and the newer Prostate Imaging—Reporting and Data System version 2.
1. Shin T, Smyth TB, Ukimura O, et al. Detection of Prostate Cancer Using Magnetic Resonance Imaging/Ultrasonography Fusion Targeted Biopsy in African-American Men. BJUI. 23 January 2017. In press. DOI: 10.1111/bju.13786