The impact of primary Gleason pattern on survival following brachytherapy for Gleason score 7 prostate cancer

Abstract

15588 Background: A recent radical prostatectomy series reported lower rates of biochemical control and cause-specific survival in Gleason score 7 patients with primary Gleason pattern 4. In this study, we evaluated the impact of Gleason 4+3 versus 3+4 on cause-specific, biochemical progression-free and overall survival in patients managed with permanent prostate brachytherapy. Methods: From April 1995 to June 2003, 530 prostate cancer patients underwent brachytherapy for clinical stage T1b-T3c (2002 AJCC) prostate cancer with Gleason score 3+4 (n=300) or Gleason score 4+3 (n=230) histology. All patients underwent brachytherapy more than three years prior to analysis. The mean and median follow-up was 6.0 and 5.7 years, respectively (range 3.2–11.2 years). Of the evaluated cohort, 412 (77.7%) received supplemental XRT and 177 (33.4%) received androgen deprivation therapy. No statistical differences were discerned between the use of XRT, however, Gleason 4+3 patients were more likely (37.4% versus 30.3%, p=0.002) to receive ADT. Multiple clinical, treatment and dosimetric parameters were evaluated as predictors of cause-specific, biochemical progression-free and overall survival. Results: At 10 years, primary Gleason 3+4 versus 4+3 did not predict for cause-specific survival (96.7% versus 93.3%, p=0.506), biochemical progression-free (97.0 versus 92.9%, p=0.085) or overall survival (77.0% versus 78.0%, p=0.9333). Cox linear regression analysis demonstrated no significant predictors for cause-specific survival while pre-treatment PSA, prostate volume and clinical stage predicted for biochemical progression-free survival. Patient age, tobacco use and diabetes were the strongest predictor for overall survival. To date, 57 patients have died (25 with Gleason 4+3 and 32 with Gleason 3+4). Of the deaths, 76% were due to cardiovascular events or second malignancies. To date, 4 patients (2 in each cohort) have died of metastatic prostate cancer. Conclusions: Following brachytherapy, the primary Gleason pattern did not impact cause-specific, biochemical progression-free or overall survival in Gleason score 7 prostate cancer. Cardiovascular disease and second malignancies were responsible for 9 times more deaths than prostate cancer. No significant financial relationships to disclose.