Linac-based stereotactic body radiation therapy for low and intermediate-risk prostate cancer: Long-term results and factors predictive for outcome and toxicity

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Abstract

INTRODUCTION: Stereotactic body radiation therapy (SBRT) is considered an effective and safe treatment in patients with low- and intermediate-risk prostate cancer (PC). However, due to a lack of long-term follow-up and late toxicity data, this treatment is not universally accepted. The present study aimed to evaluate outcome and early and late toxicity in a cohort of patients with low- and intermediate-risk PC treated prospectively with linear accelerator (linac)-based SBRT.

PATIENTS AND METHODS: Patients with low- or intermediate-risk (NCCN criteria) PC were included. All patients received linac-based SBRT to 35 Gy in 5 fractions delivered on alternate days. Endpoints were toxicity, biochemical relapse-free survival (BRFS), metastatic progression-free survival (mPFS), and overall survival (OS).

RESULTS: From 2012 to 2018, 178 patients were treated. Median baseline prostate-specific antigen (iPSA) was 6.37 ng/ml (range 1.78-20). Previous transurethral resection of the prostate (TURP) was present in 23 (12.9%) patients. Median follow-up was 58.9 months (range 9.7-89.9). BRFS rates at 1, 3, and 5 years were 98.3 (95% confidence interval, CI, 94.7-99.4%), 94.4 (95%CI 89.4-97), and 91.6% (95%CI 85.4-95.2), respectively. In univariate analysis, performance status (PS), iPSA, and nadir PSA (nPSA) were correlated with BRFS. In multivariable analysis iPSA and nPSA remained significant. BRFS rates at 5 years were 94.9% (95%CI 86.8-98) for International Society of Urological Pathology (ISUP) grade group 1, 93.2% (95%CI 80.5-97.7) for ISUP group 2, and 74.8% (95%CI 47.1-89.5) for ISUP group 3. At 1, 3, and 5 years, mPFS rates were 98.8 (95%CI 95.5-99.7), 96.2 (95%CI 91.9-98.3), and 92.9% (95%CI 87.2-96.2), respectively; OS rates were 100, 97.2 (95%CI 92.9-98.9), and 95.1% (95%CI 90-97.6), respectively. One (0.56%) case of grade 3 acute genitourinary (GU), one case of acute gastrointestinal (GI), and one case of grade 3 late GU toxicity were observed. GI toxicity positively correlated with prostate volume.

CONCLUSION: At long-term follow-up, linac-based SBRT continues to be a valid option for the management localized PC. Biochemical control remains high at 5 years, albeit with some concerns regarding the optimal schedule for unfavorable intermediate-risk PC. Considering the excellent prognosis, patient selection is crucial for prevention of severe late toxicity.

Original languageEnglish
Pages (from-to)608-616
Number of pages9
JournalStrahlentherapie und Onkologie
Volume196
Issue number7
DOIs
Publication statusPublished - Jul 2020

Keywords

  • Adenocarcinoma/blood
  • Aged
  • Aged, 80 and over
  • Combined Modality Therapy
  • Dose Fractionation, Radiation
  • Gastrointestinal Diseases/etiology
  • High-Intensity Focused Ultrasound Ablation
  • Humans
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Organ Size
  • Particle Accelerators
  • Progression-Free Survival
  • Prostate-Specific Antigen/blood
  • Prostatic Neoplasms/blood
  • Radiosurgery/adverse effects
  • Risk Factors
  • Transurethral Resection of Prostate
  • Treatment Outcome
  • Tumor Burden
  • Urination Disorders/etiology

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