External beam radiotherapy for stage T1/T2 prostate cancer: how does it stack up?

Area of Science:

• Oncology
• Radiation Oncology
• Urologic Oncology

Background:

• External beam radiation therapy (EBRT) is a primary treatment for localized prostate cancer.
• Optimizing radiation dose is crucial for maximizing treatment efficacy and minimizing side effects.
• Comparing EBRT outcomes to surgery (prostatectomy) and brachytherapy (iodine-125 implants) is essential for treatment selection.

Purpose of the Study:

• To evaluate the impact of radiation dose on treatment response in Stage T1/T2 prostate cancer.
• To compare clinical and biochemical control rates of EBRT with radical prostatectomy and iodine-125 seed implants.
• To identify optimal radiation dosing strategies for improved prostate cancer management.

Main Methods:

• A cohort of 643 patients with Stage T1/T2 prostate cancer treated with EBRT (1987-1995) was analyzed.
• Patients received isocenter doses ranging from 60 to 78 Gy (mean 67 Gy) without neoadjuvant/adjuvant androgen ablation.
• The primary endpoint was freedom from relapse or rising prostate-specific antigen (PSA) levels, with a median follow-up of 43 months.

Main Results:

• Patients receiving higher radiation doses (>67 Gy) demonstrated a significantly better 4-year freedom from failure rate (87%) compared to those receiving lower doses (≤67 Gy, 67%; P <0.0001).
• Multivariate analysis confirmed that isocenter dose was an independent predictor of outcome, alongside Gleason score and pretreatment PSA.
• Higher radiation doses were associated with superior biochemical and clinical control.

Conclusions:

• External beam radiation therapy doses exceeding 67 Gy yield very high freedom from failure rates in prostate cancer.
• These outcomes are competitive with published results from radical prostatectomy and iodine-125 seed implant series.
• Further long-term follow-up is warranted to confirm the sustained efficacy of higher radiation doses.