ORLANDO, FL USA (UroToday.com) - Dr. Magi-Galluzzi’s group re-analyzed their radical prostatectomy (RP) cohort (127 patients with and 374 without clinical recurrence (CR)) to evaluate if GPS predicts CR after biochemical recurrence (BCR) and also to assess the impact of salvage therapies. These men had all undergone RP for T1 and T2 disease. Gene expression was measured in fixed paraffin-embedded tumor specimens by RT-PCR. GPS was assessed in the dominant Gleason pattern from RPs using the genes and algorithm from the validation study. BCR was defined as two successive PSA > 0.2 ng/ml. Analysis used Cox proportional hazards models with left truncation adjustment for the time between RP and BCR.
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They found that 185 men experienced BCR, of which 53% (98 patients) developed CR (79% metastases). They performed 3 sub-analyses: 88 men who received salvage androgen deprivation therapy (ADT) [49 CRs (56%)], 57 men who received salvage radiation (XRT) [26 CRs (46%)], and 69 men who received no salvage therapy [42 CRs (61%)]. GPS was predictive of CR in all groups in univariate (HR= 2.06, p < 0.001), and remained significant after adjusting for Gleason score (GS ≤ 7 vs GS ≥ 8) or pT stage. In univariate analysis, GPS was also predictive of CR in men within each subset: salvage ADT (HR= 2.04, p = 0.021), salvage XRT (HR=2.14, p = 0.027), and no salvage therapy (HR= 1.92, p = 0.011). The GPS components that were predictive of CR were androgen genes for ADT (p = 0.01), stromal response and androgen gene groups for XRT (p < 0.015), and cellular organization genes for men receiving no salvage therapy (p < 0.001).
The GPS (a biopsy-based gene expression assay) has been shown, by different institutions, to be a predictor of adverse pathology at the time RP. Although external validation and further studies are needed, the presented data here suggests that GPS, independent of salvage therapy, can predict risk of CR for those men who show BCR after surgery.
Presented by Cristina Magi-Galluzzi, MD, PhD at the American Urological Association (AUA) Annual Meeting - May 16 - 21, 2014 - Orlando, Florida USA
Cleveland Clinic, Cleveland, OH USA
Written by Reza Mehrazin, MD, medical writer for UroToday.com