PURPOSE

To investigate whether expression signatures from Grade Group 1 (GG1) biopsy cores can detect the presence of higher-grade cancer elsewhere in the prostate.

MATERIALS AND METHODS

We enrolled 205 men with low to favorable intermediate-risk prostate cancer undergoing active surveillance on a prospective protocol. All participants underwent MRI and confirmatory biopsy at enrollment, followed by annual biopsies for 3 more years. Select cores were sent for Decipher genomic classifier (DGC) testing, and derived Genomic Prostate Score (dGPS) and Cell Cycle Progression (dCCP) signatures were obtained. We compared genomic scores from GG1 biopsy cores with vs without coexisting GG2 and GG3 or higher cancer (GG2+ and GG3+, respectively). We repeated this comparison using only the highest-volume GG1 core from each biopsy, which is the current standard of care.

RESULTS

Genomic profiling was successful in 141 of 205 patients (324 GG1 cores). There were no significant differences in DGC, dCCP, or dGPS scores between GG1 cores with vs without coexisting GG2+ cancer elsewhere. This remained true, when using the largest volume GG1 core from each biopsy. dGPS was higher among GG1 cores with coexisting GG3+ cancer compared with those without (0.24 vs 0.10, = .012); however, there was no difference between the groups on DGC or dCCP scores.

CONCLUSIONS

Genomic classifiers in GG1 cores did not predict coexisting GG2+ cancer, while dGPS signatures showed some promise in detecting GG3+ cancer elsewhere in the gland. None of the signatures showed a difference between groups when using the highest volume GG1 core, which is the standard practice for genomic classifiers.