title: Integration of (68)Ga-PSMA-PET imaging in planning of primary definitive radiotherapy in prostate cancer: a retrospective study.
abstract: BACKGROUND
  Prostate cancer (PC) is one of the most commonly treated cancer entities with radiation therapy (RT). Risk group-adapted treatment and avoidance of unnecessary toxicities relies primarily on accurate tumor staging. Thus, the introduction of prostate-specific membrane antigen (PSMA) in diagnosis and treatment of PC is a highly interesting development in radiation oncology of urologic tumors. The present work is to evaluate the integration of (68)Ga-PSMA-PET imaging into standard radiation planning of primary definitive treatment of PC and to determine the impact of PSMA imaging on tumor staging.
  
  
  METHODS
  The data of 15 patients treated for PC between August 2013 and April 2015 were evaluated. Treatment planning included (68)Ga-PSMA-PET imaging. We analyzed whether the use of PSMA-imaging led to a change of the TNM stage and if it influenced the RT treatment approach or the target volume, due to changes in the gross tumor volume (GTV) or clinical target volume (CTV), in the final treatment plan.
  
  
  RESULTS
  In 53.3 % of the analyzed patients a change occurred in the TNM stage based on (68)Ga-PSMA-PET examination. The RT concept changed in 33.3 % of all patients, leading to relevant changes in the planning target volume. Among these, an additional irradiation of the pelvic lymph drainage due to tracer uptake in lymph nodes was performed in 25 %. Furthermore, boost volumes of PET-positive lymph nodes were added in 80 % of these cases. A down staging due to the (68)Ga-PSMA-PET examination occurred in 13.3 % of all cases.
  
  
  CONCLUSIONS
  The integration of (68)Ga-PSMA-PET-imaging into the RT treatment planning process can be useful for detailed target volume planning. The performance of a (68)Ga-PSMA-PET frequently leads to changes in the TNM stage, altering the RT treatment regimen and the target volume. A prospective trial is underway to evaluate the impact of (68)Ga-PSMA-PET based treatment planning on outcome.
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany. sabrina.dewes@mri.tum.de.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Dewes
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Kilian
authors.initials: K
authors.lastname: Schiller
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Sauter
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Eiber
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Maurer
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Jürgen E
authors.initials: JE
authors.lastname: Gschwend
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Combs
authors.affiliation: Technische Universität München (TUM), Klinik und Poliklinik für RadioOnkologie und Strahlentherapie, Ismaninger Straße 22, 81675, Munchen, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Habl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000954:Antigens, Surface / Q000378:metabolism*; D004492:Edetic Acid / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005500:Follow-Up Studies; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D043425:Glutamate Carboxypeptidase II / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000493:pharmacokinetics*; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D014018:Tissue Distribution
chemical_list: D000954:Antigens, Surface; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; D019275:Radiopharmaceuticals; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II
keywords: PSMA-PET; Prostate cancer; Radiation oncology; Radiation therapy; Treatment planning