Long-term outcomes of dose-escalated intensity modulated radiation therapy alone without androgen deprivation therapy for patients with intermediate and high-risk prostate cancer.

Objective: The addition of androgen deprivation therapy (ADT) to conventional radiation therapy improves overall survival (OS) in intermediate- and high-risk prostate cancer. The benefit of ADT to added to dose-escalated radiotherapy is less clear. The aim of this study was to report disease control outcomes and to identify prognostic variables associated with favorable outcomes in patients with intermediate- and high-risk prostate cancer treated with dose-escalated radiation therapy without ADT.

Methods And Materials: From September 2001 to March 2010, 127 patients with intermediate- or high-risk prostate cancer were treated with dose-escalated radiation otherapy without ADT. Biochemical recurrence-free survival (bRFS), distant metastases-free survival (DMFS), prostate cancer-specific mortality, and OS were assessed. Univariate and multivariate analyses using Cox regression modeling were performed.

Results: The median follow-up was 6.5 years, and the 5-year estimated bRFS, DMFS, prostate cancer-specific mortality, and OS for all patients was 89%, 96.1%, 98.4%, and 96.9% respectively. On multivariate analysis, factors that predict bRFS include risk group and PSA nadir, and factors that predict DMFS include perineural invasion, risk group, and PSA nadir.

Conclusions: Patients with favorable intermediate-risk cancer could likely be treated with dose-escalated radiation therapy without ADT. Patients with high-risk and unfavorable intermediate-risk cancer, perineural invasion, and PSA nadir ≥1ng/dL had worse outcomes and likely need distinct therapeutic approaches.