title: Anterior-oriented proton beams for prostate cancer: A multi-institutional experience.
abstract: BACKGROUND
  Proton beam therapy (PBT) for prostate cancer generally involves the use of two lateral beams that transverse the hips. In patients with hip replacements or a previously irradiated hip, this arrangement is contraindicated. The use of non-lateral beams is possible, but not well described. Here we report a multi-institutional experience for patients treated with at least one non-lateral proton beam for prostate cancer.
  
  
  METHODS
  Between 2010 and 2014, 20 patients with organ-confined prostate cancer and a history of hip prosthesis underwent proton therapy utilizing at least one anterior oblique beam (defined as between 10° and 85° from vertical) at one of three proton centers.
  
  
  RESULTS
  The median follow-up was 6.4 months. No patients have developed PSA failure or distant metastases. The median planning target volume (PTV) D95 was 79.2 Gy (RBE) (range 69.7-79.9). The median rectal V70 was 9.2% (2.5-15.4). The median bladder V50, V80, and mean dose were 12.4% (3.7-27.1), 3.5 cm3 (0-7.1), and 14.9 Gy (RBE) (4.6-37.8), respectively. The median contralateral femur head V45 and max dose were 0.01 cm3 (0-16.6) and 43.7 Gy (RBE) (15.6-52.5), respectively. The incidence of acute Grade 2 urinary toxicity was 40%. There were no Grade≥3 urinary toxicities. There was one patient who developed late Grade 2 rectal proctitis, with no other cases of acute or late ≥Grade 2 gastrointestinal toxicity. Grade 2 erectile dysfunction occurred in two patients (11.1%). Mild hip pain was experienced by five patients (25%). There were no cases of hip fracture.
  
  
  CONCLUSIONS
  PBT for prostate cancer utilizing anterior oblique beam trajectories is feasible with favorable dosimetry and acceptable toxicity. Further follow-up is needed to assess for long-term outcomes and toxicities.
authors.affiliation: Memorial Sloan Kettering Cancer Center and Procure Proton Therapy Center , Somerset, NJ , USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Cuaron
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Harris
authors.forename: Brian
authors.initials: B
authors.lastname: Chon
authors.forename: Henry
authors.initials: H
authors.lastname: Tsai
authors.forename: Gary
authors.initials: G
authors.lastname: Larson
authors.forename: William F
authors.initials: WF
authors.lastname: Hartsell
authors.forename: Eugen
authors.initials: E
authors.lastname: Hug
authors.forename: Oren
authors.initials: O
authors.lastname: Cahlon
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000209:etiology; D007172:Erectile Dysfunction / Q000209:etiology; D005270:Femur Head / Q000528:radiation effects*; D006621:Hip Joint; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D011349:Proctitis / Q000209:etiology; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011832:Radiation Injuries / Q000209:etiology*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000528:radiation effects*; D001743:Urinary Bladder / Q000528:radiation effects*
chemical_list: D017430:Prostate-Specific Antigen