The potential of intensity-modulated proton radiotherapy to reduce swallowing dysfunction in the treatment of head and neck cancer: A planning comparative study.
Summary of "The potential of intensity-modulated proton radiotherapy to reduce swallowing dysfunction in the treatment of head and neck cancer: A planning comparative study."
Background. Predictive models for swallowing dysfunction were developed previously and showed the potential of improved intensity-modulated radiotherapy to reduce the risk of swallowing dysfunction. Still the risk is high. The aim of this study was to determine the potential of swallowing-sparing (SW) intensity-modulated proton therapy (IMPT) in head and neck cancer (HNC) for reducing the risk of swallowing dysfunction relative to currently used photon therapy. Material and methods. Twenty-five patients with oropharyngeal (n = 21) and hypopharyngeal (n = 4) cancer received primary radiotherapy, including bilateral neck irradiation, using standard (ST) intensity-modulated photon therapy (IMRT). Prophylactic (54 Gy) and therapeutic (70 Gy) target volumes were defined. The dose to the parotid and submandibular glands was reduced as much as possible. Four additional radiotherapy plans were created for each patient: SW-IMRT, ST-IMPT, 3-beam SW-IMPT (3B-SW-IMPT) and 7-beam SW-IMPT (7B-SW-IMPT). All plans were optimized similarly, with additional attempts to spare the swallowing organs at risk (SWOARs) in the SW plans. Probabilities of swallowing dysfunction were calculated with recently developed predictive models. Results. All plans complied with standard HNC radiotherapy objectives. The mean parotid gland doses were similar for the ST and SW photon plans, but clearly lower in all IMPT plans (ipsilateral parotid gland ST-
IMRT:
46 Gy, 7B-SW-
IMPT:
29 Gy). The mean dose in the SWOARs was lowest with SW-IMPT, in particular with 7B-SW-IMPT (supraglottic larynx ST-
IMRT:
60 Gy, 7B-SW-
IMPT:
40 Gy). The observed dose reductions to the SWOARs translated into substantial overall reductions in normal tissue complication risks for different swallowing dysfunction endpoints. Compared with ST-IMRT, the risk of physician-rated grade 2-4 swallowing dysfunction was reduced on average by 8.8% (95% CI 6.5-11.1%) with SW-IMRT, and by 17.2% (95%
CI:
12.7-21.7%) with 7B-SW-IMPT. Conclusion. SWOAR-sparing with proton therapy has the potential to substantially reduce the risk of swallowing dysfunction compared to similar treatment with photons.
Affiliation
University of Groningen, University Medical Center Groningen, Department of Radiation Oncology , Groningen , The Netherlands.
Journal Details
This article was published in the following journal.
Name: Acta oncologica (Stockholm, Sweden)
ISSN: 1651-226X
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22708528
- DOI: http://dx.doi.org/10.3109/0284186X.2012.692885
Medical and Biotech [MESH] Definitions
Radiotherapy, Intensity-modulated
CONFORMAL RADIOTHERAPY that combines several intensity-modulated beams to provide improved dose homogeneity and highly conformal dose distributions.
Radiotherapy, Adjuvant
Radiotherapy given to augment some other form of treatment such as surgery or chemotherapy. Adjuvant radiotherapy is commonly used in the therapy of cancer and can be administered before or after the primary treatment.
Radiotherapy Dosage
The total amount of radiation absorbed by tissues as a result of radiotherapy.
Electron Transport Chain Complex Proteins
A complex of enzymes and PROTON PUMPS located on the inner membrane of the MITOCHONDRIA and in bacterial membranes. The protein complex provides energy in the form of an electrochemical gradient, which may be used by either MITOCHONDRIAL PROTON-TRANSLOCATING ATPASES or BACTERIAL PROTON-TRANSLOCATING ATPASES.
Proton-motive Force
Energy that is generated by the transfer of protons or electrons across an energy-transducing membrane and that can be used for chemical, osmotic, or mechanical work. Proton-motive force can be generated by a variety of phenomena including the operation of an electron transport chain, illumination of a PURPLE MEMBRANE, and the hydrolysis of ATP by a proton ATPase. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed, p171)
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