A retrospective study of late adverse events in proton beam therapy for prostate cancer

Abstract

The efficacy and safety of proton beam therapy (PBT) were retrospectively evaluated in 111 consecutive patients with prostate cancer who underwent definitive PBT between 2008 and 2012. Following exclusion of 18 patients due to treatment suspension, loss to follow-up, and histology, the analysis included 93 patients with a median age of 68 years (range, 49-81 years). A total of 7, 32 and 54 prostate cancer patients were classified as low-, intermediate- and high-risk, respectively, as follows: High-risk, T>/=3a or prostate-specific antigen (PSA) >/=20 ng/ml or Gleason Score >/=8; low-risk, T 2 years after PBT, and all but one were PSA failure-free. The Common Terminology Criteria for Adverse Events v.4.0 was used to evaluate late adverse events. One patient developed grade 3 non-infectious cystitis and hematuria. Grade 2 urinary frequency was observed in 1 patient, and grade 2 rectal bleeding occurred in 4 patients. Of the 4 patients with grade 2 rectal bleeding, 2 received anticoagulant therapy, but none had diabetes mellitus or another high-risk comorbidity. The median time to occurrence of an adverse event of grade >/=2 was 14 months (range, 3-41 months). Therefore, the present retrospective study revealed that PBT at 78 GyE/39 Fr was well-tolerated and achieved good tumor control in patients with prostate cancer.