Outcomes in patients with high- and very high-risk localized prostate cancer treated with definitive IMRT and long-term hormone therapy

Abstract

Background: The aim of this study was to evaluate the effectiveness of intensity-modulated radiation therapy in combination with long-term androgen deprivation therapy for high-risk and very high-risk localized prostate cancer while also investigating factors associated with the therapeutic effect.

Methods: Men who fulfilled criteria for the National Comprehensive Cancer Network high-risk or very high-risk localized prostate cancer and were treated with definitive intensity-modulated radiation therapy (74-78 Gy) of the prostate and the seminal vesicle combined with androgen deprivation therapy in our institution from 2007 to 2016 were identified (n = 197). In principle, patients received androgen deprivation therapy for 3-6 months before radiation, concurrently, and for 2 years after completion of intensity-modulated radiation therapy.

Results: The median follow-up period was 96 months. The 5-year and 10-year overall survival rates in the overall population were 96.9% and 89.3%, respectively. The 5-year and 10-year cumulative incidence rates of biochemical failure were 2.5% and 16.3% in the high-risk group, and 8.6% and 32.0% in the very high-risk group, respectively, indicating a significant difference between the two groups (P = 0.023). Grade Group 5 and younger age (cutoff: 70 years old) were independent predictors of recurrence (P = 0.016 and 0.017, respectively). Patients exhibiting biochemical failure within <18 months after completion of androgen deprivation therapy displayed an increased risk of cancer-specific mortality (P = 0.039) when contrasted with those who had a longer interval to biochemical failure.

Conclusions: Patients with the National Comprehensive Cancer Network very high-risk prostate cancer, particularly those with Grade Group 5 and younger age, showed worse outcomes following intensity-modulated radiation therapy and long-term androgen deprivation therapy.

Keywords: prognostic factor; prostate cancer; radiotherapy; treatment outcome.