Prostate brachytherapy, either alone or in combination with external beam radiation, is associated with longer overall survival in men with favorable pathologic Group 4 (Gleason score 8) prostate cancer.

PURPOSE

Conventional prostate cancer risk stratification results in considerable heterogeneity within each prognostic group. Men with pathologic grade Group 4 (Gleason score 8) but otherwise low-risk features have been identified as a favorable subset of high-risk prostate cancer. Given recent randomized data supporting improved cancer outcome with brachytherapy in intermediate- and high-risk prostate cancer, we sought to evaluate brachytherapy utilization and overall survival (OS) for these patients.

METHODS AND MATERIALS

We queried the National Cancer Database for clinical T1c-T2a N0 M0 prostate cancer with prostate-specific antigen <10 ng/mL and Gleason score 8 adenocarcinoma on biopsy. All patients received androgen deprivation therapy and either external beam radiation therapy (EBRT) alone, brachytherapy alone, or a combination of EBRT with brachytherapy boost (brachytherapy + EBRT). Kaplan-Meier OS estimates as well as univariate and multivariate Cox proportional hazards regression analyses were performed. Propensity score-matched analyses were performed to further control for baseline confounders.

RESULTS

Four thousand four hundred ninety-six patients were identified with a median followup of 62.5 months (range, 2.3-119.8). Median age was 72 years (range, 41-90+). Utilization of brachytherapy decreased from 2004 to 2009. The odds ratio for brachytherapy by year (continuous variable) was 0.86 (p < 0.001). Five-year OS was 84%, 88%, and 89% for the EBRT alone, brachytherapy alone, and brachytherapy + EBRT groups, respectively. On multivariate analysis, higher median income, low comorbidity score, and treatment with brachytherapy alone (hazard ratio, 0.66; p = 0.005) or brachytherapy + EBRT (hazard ratio, 0.70; p = 0.001) remained associated with longer OS. Propensity score matching confirmed longer OS associated with either brachytherapy regimen.

CONCLUSIONS

Of those men with World Health Organization pathologic grade Group 4 (Gleason score 8) prostate cancer and otherwise favorable prognostic features treated with androgen deprivation therapy and radiation therapy, longer OS was achieved when prostate brachytherapy was included, whether used alone or in combination with supplemental EBRT. In spite of these excellent outcomes, prostate brachytherapy utilization is declining in the United States.