NTCP reduction for advanced head and neck cancer patients using proton therapy for complete or sequential boost treatment versus photon therapy.
BACKGROUND
To determine by treatment plan comparison differences in toxicity risk reduction for patients with head and neck squamous cell carcinoma (HNSCC) from proton therapy either used for complete treatment or sequential boost treatment only.


METHODS
For 45 HNSCC patients, intensity-modulated photon (IMXT) and proton (IMPT) treatment plans were created including a dose escalation via simultaneous integrated boost with a one-step adaptation strategy after 25 fractions for sequential boost treatment. Dose accumulation was performed for pure IMXT treatment, pure IMPT treatment and for a mixed modality treatment with IMXT for the elective target followed by a sequential boost with IMPT. Treatment plan evaluation was based on modern normal tissue complication probability (NTCP) models for mucositis, xerostomia, aspiration, dysphagia, larynx edema and trismus. Individual NTCP differences between IMXT and IMPT (∆NTCPIMXT-IMPT) as well as between IMXT and the mixed modality treatment (∆NTCPIMXT-Mix) were calculated.


RESULTS
Target coverage was similar in all three scenarios. NTCP values could be reduced in all patients using IMPT treatment. However, ∆NTCPIMXT-Mix values were a factor 2-10 smaller than ∆NTCPIMXT-IMPT. Assuming a threshold of ≥ 10% NTCP reduction in xerostomia or dysphagia risk as criterion for patient assignment to IMPT, less than 15% of the patients would be selected for a proton boost, while about 50% would be assigned to pure IMPT treatment. For mucositis and trismus, ∆NTCP ≥ 10% occurred in six and four patients, respectively, with pure IMPT treatment, while no such difference was identified with the proton boost.


CONCLUSIONS
The use of IMPT generally reduces the expected toxicity risk while maintaining good tumor coverage in the examined HNSCC patients. A mixed modality treatment using IMPT solely for a sequential boost reduces the risk by 10% only in rare cases. In contrast, pure IMPT treatment may be reasonable for about half of the examined patient cohort considering the toxicities xerostomia and dysphagia, if a feasible strategy for patient anatomy changes is implemented.
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Annika
A
Jakobi
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Kristin
K
Stützer
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|b Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.
Anna
A
Bandurska-Luque
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Steffen
S
Löck
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Robert
R
Haase
c Section for Biomedical Physics, University Hospital for Radiation Oncology, Eberhard Karls Universät Tübingen , Germany.
Linda-Jacqueline
LJ
Wack
c Section for Biomedical Physics, University Hospital for Radiation Oncology, Eberhard Karls Universät Tübingen , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|e German Cancer Consortium (DKTK) , Tübingen , Germany.
David
D
Mönnich
c Section for Biomedical Physics, University Hospital for Radiation Oncology, Eberhard Karls Universät Tübingen , Germany.
Daniel
D
Thorwarth
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|f German Cancer Consortium (DKTK) , Dresden , Germany.
Damien
D
Perez
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|f German Cancer Consortium (DKTK) , Dresden , Germany.
Armin
A
Lühr
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Daniel
D
Zips
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|b Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|f German Cancer Consortium (DKTK) , Dresden , Germany.|g Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology , Dresden , Germany.
Mechthild
M
Krause
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|b Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|f German Cancer Consortium (DKTK) , Dresden , Germany.|g Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology , Dresden , Germany.
Michael
M
Baumann
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.
Rosalind
R
Perrin
a OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf , Dresden , Germany.|b Department of Radiation Oncology , Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden , Dresden , Germany.|d German Cancer Research Center (DKFZ) , Heidelberg , Germany.|f German Cancer Consortium (DKTK) , Dresden , Germany.|g Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology , Dresden , Germany.
Christian
C
Richter
D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D003680:Deglutition Disorders / Q000209:etiology; D004487:Edema / Q000209:etiology; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007818:Laryngeal Diseases / Q000209:etiology; D015233:Models, Statistical; D052016:Mucositis / Q000209:etiology; D058958:Organs at Risk; D017785:Photons / Q000009:adverse effects* / Q000627:therapeutic use; D011336:Probability; D061766:Proton Therapy / Q000009:adverse effects* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D053120:Respiratory Aspiration / Q000209:etiology; D014313:Trismus / Q000209:etiology; D014987:Xerostomia / Q000209:etiology