The impact of primary Gleason grade on biochemical outcome following brachytherapy for hormone-naive Gleason score 7 prostate cancer.

PURPOSE Although the perception exists that biochemical outcome in patients with a Gleason score of 7 with dominant pattern 4 histology is inferior to that of patients with a Gleason score of 7 with a primary Gleason grade of 3, conflicting conclusions have been reported for radical prostatectomy and brachytherapy. In this study, we evaluate the effect of the dominant histologic pattern in Gleason score 7 prostate cancer on biochemical progression-free survival after brachytherapy. MATERIAL AND METHODS Between April 1995 and October 2001, 273 consecutive patients underwent permanent interstitial brachytherapy without androgen deprivation therapy for clinical T1c-T3a NxM0 (2002 American Joint Committee on Cancer) prostate cancer. No patient underwent seminal vesicle biopsy or pathological lymph node staging. All patients underwent brachytherapy more than 3 years before analysis. Biochemical progression-free survival was defined by a prostate specific antigen (PSA) cut point < or = 0.4 ng/mL after nadir or by the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definition. The median follow-up was 4.7 years. Clinical, treatment, and dosimetric parameters evaluated for biochemical progression-free survival included primary Gleason grade; clinical T stage; pretreatment PSA level; risk group; percent positive biopsy results; perineural invasion; patient age; isotope; supplemental external-beam radiation therapy; prostate volume; brachytherapy planning volume; percent of the target volume receiving 100%, 150%, and 200% of the prescribed dose (V100/150/200); minimum percent of the prescribed dose covering 90% of the target volume (D90); tobacco consumption; hypertension; and diabetes. RESULTS For the entire cohort, the actuarial 8-year biochemical progression-free survival rate was 94.5% and 94.8% using a PSA cut point < or = 0.4 ng/mL after nadir and the ASTRO consensus definition, respectively. For biochemically disease free patients, the median posttreatment PSA level was < 0.1 ng/mL. When the group was stratified by the dominant histologic pattern, no statistical difference in outcome was noted for any of the evaluated parameters. In forward conditional Cox regression analysis, pretreatment PSA level and percent positive biopsy results were statistically significant predictors of biochemical outcome. CONCLUSIONS In hormone-naive patients with a Gleason score of 7, prostate brachytherapy results in a high probability of 8-year biochemical progression-free survival and is independent of Gleason 3 + 4 versus 4 + 3 histology.