title: Irradiation with protons for the individualized treatment of patients with locally advanced rectal cancer: a planning study with clinical implications.
abstract: OBJECTIVE
  Ongoing clinical trials aim to improve local control and overall survival rates by intensification of therapy regimen for patients with locally advanced rectal cancer. It is well known that whenever treatment is intensified, risk of therapy-related toxicity rises. An irradiation with protons could possibly present an approach to solve this dilemma by lowering the exposure to the organs-at-risk (OAR) without compromising tumor response.
  
  
  METHODS
  Twenty five consecutive patients were treated from 04/2009 to 5/2010. For all patients, four different treatment plans including protons, RapidArc, IMRT and 3D-conformal-technique were retrospectively calculated and analyzed according to dosimetric aspects.
  
  
  RESULTS
  Detailed DVH-analyses revealed that protons clearly reduced the dose to the OAR and entire normal tissue when compared to other techniques. Furthermore, the conformity index was significantly better and target volumes were covered consistent with the ICRU guidelines.
  
  
  CONCLUSIONS
  Planning results suggest that treatment with protons can improve the therapeutic tolerance for the irradiation of rectal cancer, particularly for patients scheduled for an irradiation with an intensified chemotherapy regimen and identified to be at high risk for acute therapy-related toxicity. However, clinical experiences and long-term observation are needed to assess tumor response and related toxicity rates.
authors: Department of Radiotherapy and Radiooncology, University Medical Center, Göttingen, Germany. hendrik.wolff@med.uni-goettingen.de
authors: Hendrik Andreas
authors: HA
authors: Wolff
authors: Daniela Melanie
authors: DM
authors: Wagner
authors: Lena-Christin
authors: LC
authors: Conradi
authors: Steffen
authors: S
authors: Hennies
authors: Michael
authors: M
authors: Ghadimi
authors: Clemens Friedrich
authors: CF
authors: Hess
authors: Hans
authors: H
authors: Christiansen
mesh_terms: D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000528:radiation effects; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D057285:Precision Medicine; D061766:Proton Therapy; D011836:Radiation Tolerance; D011874:Radiometry; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D012189:Retrospective Studies; D013737:Testis / Q000528:radiation effects; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000528:radiation effects; D011522:Protons
chemical_list: D011522:Protons