International Journal of Particle Therapy (Oct 2021)

Long-term Clinical Outcomes in Favorable Risk Prostate Cancer Patients Receiving Proton Beam Therapy

  • Alicia Bao, BS,
  • Andrew R. Barsky, MD,
  • Russell Maxwell, MD,
  • Justin E. Bekelman, MD,
  • Stefan Both, PhD,
  • John P. Christodouleas, MD, MPH,
  • Curtiland Deville, Jr, MD,
  • Penny Fang, MD,
  • Zelig A. Tochner, MD,
  • Neha Vapiwala, MD

DOI
https://doi.org/10.14338/IJPT-21-00016
Journal volume & issue
Vol. 8, no. 4
pp. 14 – 24

Abstract

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Purpose: Long-term data regarding the disease control outcomes of proton beam therapy (PBT) for patients with favorable risk intact prostate cancer (PC) are limited. Herein, we report our institution's long-term disease control outcomes in PC patients with clinically localized disease who received PBT as primary treatment. Methods: One hundred sixty-six favorable risk PC patients who received definitive PBT to the prostate gland at our institution from 2010 to 2012 were retrospectively assessed. The outcomes studied were biochemical failure-free survival (BFFS), biochemical failure, local failure, regional failure, distant failure, PC-specific survival, and overall survival. Patterns of failure were also analyzed. Multivariate Cox proportional hazards modeling was used to estimate independent predictors of BFFS. Results: The median length of follow-up was 8.3 years (range, 1.2–10.5 years). The majority of patients had low-risk disease (58%, n = 96), with a median age of 64 years at the onset of treatment. Of 166 treated men, 13 (7.8%), 8 (4.8%), 2 (1.2%) patient(s) experienced biochemical failure, local failure, regional failure, respectively. Regional failure was seen in an obturator lymph node in 1 patient and the external iliac lymph nodes in the other. None of the patients experienced distant failure. There were 5 (3.0%) deaths, none of which were due to PC. The 5- and 8-year BFFS rate were 97% and 92%, respectively. None of the clinical disease characteristics or treatment-related factors assessed were associated with BFFS on multivariate Cox proportional hazards modeling (all P >.05). Conclusion: Disease control rates reported in our assessment of PBT were similar to those reported in previous clinically localized intact PC analyses, which used intensity-modulated radiotherapy, three-dimensional conformal radiotherapy, or radical prostatectomy as definitive therapy. In addition, BFFS rates were similar, if not improved, to previous PBT studies.

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