Dose-Escalated Stereotactic Body Radiation Therapy for Patients with Intermediate and High-Risk Prostate Cancer: Initial Dosimetry Analysis and Patient Outcomes
Menée sur 24 patients atteints d'un cancer de la prostate à risque intermédiaire ou élevé de récidive (durée médiane de suivi : 25 mois), cette étude évalue la toxicité génito-urinaire et gastro-intestinale d'une radiothérapie corporelle stéréotaxique avec escalade de doses
Résumé en anglais
Purpose : To report the short-term clinical outcomes and acute and late treatment-related genitourinary (GU) and gastrointestinal (GI) toxicities in patients with intermediate- and high-risk prostate cancer treated with dose-escalated stereotactic body radiotherapy (SBRT).
Methods and Materials : Between 2011 and 2014, 24 patients with prostate cancer were treated with SBRT to the prostate gland and proximal seminal vesicles. A high-dose avoidance zone (HDAZ) was created by a three mm expansion around the rectum, urethra, and bladder. Patients were treated to a minimum dose of 36.25 Gy in five fractions with a simultaneous dose-escalation to a dose of 50 Gy to the target volume away from the HDAZ. Acute and late GU and GI toxicity outcomes were measured according to the National Cancer Institute Common Toxicity Criteria (v4).
Results : The median follow-up was 25 months (Range: 18-45 months). Nine patients (38%) experienced an acute grade 2 GU toxicity, which was medically managed, and no patients experienced an acute Grade 2 GI toxicity. Two patients (8%) experienced late Grade 2 GU toxicity and two patients (8%) experienced late Grade 2 GI toxicity. No acute or late grade ≥ 3 GU or GI toxicities were observed. The 24-month PSA relapse-free survival outcome for all patients was 95.8% (95% CI: 75.6-99.4%) and both biochemical failures occurred in patients with high-risk disease. All patients are currently alive at the time of this analysis and continue to be followed.
Conclusions : A heterogeneous prostate SBRT planning technique with differential treatment volumes (low dose: 36.25 Gy and high-dose: 50 Gy) with a HDAZ provides a safe method of dose-escalation. Favorable rates of biochemical control and acceptably low rates of acute and long-term GU and GI toxicity can be achieved in patients with intermediate- and high-risk prostate cancer treated with SBRT.
