This group analyzed clinical outcomes for patients treated with dose-escalated radiation therapy (RT) based upon the presence or absence of GG5 within the biopsy specimens. 79 men treated for localized prostate cancer with definitive external beam RT to at least 75 Gy were identified as having GG5 and thus assessed for outcomes. Specifically they evaluated the impact of GG5 as well as pre-treatment and treatment related factors on freedom from biochemical failure (FFBF), freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival (OS).
The median follow-up in the patient cohort was 64 months. At biopsy, 89% of the entire database of 718 patients had no GG5, while 11% (79 men) had GG5. There was no difference in age, co-morbid illness, clinical T-stage, PSA, or the use or duration of androgen deprivation therapy between GS8 without GG5 and GS8-10 with GG5. The presence of GG5 predicted lower FFM (p<0.002, HR: 3.4), CSS (p<0.0001, HR: 12.9), and OS (p<0.0001, HR: 3.6) when compared to GS8 (without GG5). 10-year FFM, CSS, and OS were 89%, 98%, and 57%, respectively for those with Gleason 8 prostate cancer without GG5 as compared to 61%, 55%, and 31%, respectively for those with GG5. Both FFM and CSS were strongly influenced by androgen deprivation therapy use concurrent with RT. On multivariate analysis GG5 was the strongest prognostic factor for all clinical end-points. However, in the discussion session it was pointed out that whether the GG5 was the primary or secondary Gleason pattern was not differentiated.
Presented by Aaron Sabolch at the 2011 Genitourinary Cancers Symposium, Oral Abstract Session A: Prostate Cancer - February 17-19, 2011 - Orlando World Center Marriott, Orlando, Florida USA