Swallowing sparing intensity modulated radiotherapy (SW-IMRT) in head and neck cancer: Clinical validation according to the model-based approach

Miranda E M C Christianen; Arjen van der Schaaf; Hans Paul van der Laan; Irma M Verdonck-de Leeuw; Patricia Doornaert; Olga Chouvalova; Roel J H M Steenbakkers; Charles René Leemans; Sjoukje F Oosting; Bernard F A M van der Laan; Jan L N Roodenburg; Ben J Slotman; Hendrik P Bijl; Johannes A Langendijk

doi:10.1016/j.radonc.2015.11.009

Swallowing sparing intensity modulated radiotherapy (SW-IMRT) in head and neck cancer: Clinical validation according to the model-based approach

Radiother Oncol. 2016 Feb;118(2):298-303. doi: 10.1016/j.radonc.2015.11.009. Epub 2015 Dec 14.

Authors

Affiliations

¹ Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
² Department of Otorhinolaryngology-Head and Neck Surgery, VU University Medical Center Amsterdam, The Netherlands.
³ Department of Radiation Oncology, VU University Medical Center Amsterdam, The Netherlands.
⁴ Department of Medical Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
⁵ Department of Otorhinolaryngology-Head and Neck Surgery, University of Groningen, University Medical Center Groningen, The Netherlands.
⁶ Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, The Netherlands.
⁷ Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands. Electronic address: j.a.langendijk@umcg.nl.

PMID: 26700602
DOI: 10.1016/j.radonc.2015.11.009

Abstract

Purpose: The aim of this study was to clinically validate a multivariable normal tissue complication probability (NTCP) model for grade 2-4 swallowing dysfunction at 6months after radiotherapy or chemoradiation (SWALM6) in head and neck cancer patients treated with swallowing sparing intensity modulated radiotherapy (SW-IMRT) and to test if SW-IMRT resulted in a reduction of the prevalence of SWALM6.

Materials and methods: The primary endpoint was SWALM6. For all 186 patients, a standard IMRT (parotid sparing) and a SW-IMRT plan (additional constraints for swallowing organs at risk) was created. The difference in NTCP for SWALM6 (ΔNTCPSWALM6=NTCPstandard-NTCPSW-IMRT) was calculated. Patients were treated with SW-IMRT. The external validation of the NTCP model was analyzed by comparing performance measures.

Results: The mean ΔNTCPSWALM6 was 4.9% (range 0.01-17.3%), with a significant lower mean predicted NTCPSW-IMRT of 22.6% (95% CI 20.2-24.9%), compared to NTCPstandard of 27.5% (95% CI 24.9-29.9%) (p<0.001). There was a perfect correspondence of NTCPSW-IMRT with the observed prevalence of SWALM6 (22.6%). The overall model performance, discrimination and 'goodness of fit' were good.

Conclusion: We externally validated the multivariable NTCP model for SWALM6 in SW-IMRT treated patients, showing reduced swallowing dysfunction by reducing the dose parameters included in this NTCP model.

Keywords: Head and neck cancer; Model based approach; Radiotherapy; Swallowing sparing IMRT.

Publication types

Research Support, Non-U.S. Gov't
Validation Study

MeSH terms

Adolescent
Aged
Cohort Studies
Deglutition / radiation effects*
Deglutition Disorders / prevention & control*
Female
Head and Neck Neoplasms / radiotherapy*
Humans
Male
Middle Aged
Models, Theoretical
Probability
Prospective Studies
Radiation Injuries / prevention & control*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Intensity-Modulated / methods*
Reproducibility of Results
Young Adult