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Original article
peer-reviewed

A Dosimetric Comparison of Primary Chemoradiation Versus Postoperative Radiation for Locally Advanced Oropharyngeal Cancer



Abstract

Introduction

Advanced-stage oropharyngeal cancer can be treated with primary chemoradiation (CRT) or primary surgery with adjuvant radiotherapy, both with similar survival outcomes. Though primary CRT prescribes a higher dose, adjuvant radiation requires irradiating the surgical bed, which may increase the high dose planned target volume (PTV). We hypothesize that the integral dose to the neck and dose to critical structures will be lower with primary CRT than adjuvant radiotherapy.

Methods

We selected the last 18 patients who underwent surgery and adjuvant radiotherapy at one institution between July 2015 and August 2016 with American Joint Committee on Cancer (AJCC) stage III or IVA oropharyngeal squamous cell cancer. Primary CRT treatment plans were created on the patients’ preoperative computed tomography (CT) scans and prescribed 70 Gy in 33 fractions, while postoperative plans were prescribed 60 Gy in 30 fractions. The radiation doses received by organs at risk for each primary CRT plan were compared to the corresponding adjuvant radiation plan.

Results

 Primary CRT plans had significantly smaller high dose PTV than adjuvant radiation plans (187.3 cc (95% CI 134.9-239.7) and 466.3 cc (95% CI 356.7-575.9), p<0.0001). The neck integral dose was lower in 14 of 18 plans using primary CRT, although this was not statistically significant (p=0.5375). The primary CRT plans had lower mean doses to ipsilateral (31.8 Gy (95% CI 27.5-36.0) vs 39.3 Gy (95% CI 35.4-43.1), p=0.0009)) and contralateral parotid glands (22.5 Gy (95% CI 22.1-22.8) vs 27.6 Gy (95% CI 23.4-31.8), p=0.0238) and larynx (20.7 Gy (95% CI 19.3-22.2) vs 40.2 Gy (95% CI 30.8-46.6), p<0.0001).

Conclusion

Primary CRT offered a decreased neck integral dose, though it was statistically insignificant. Primary CRT plans reduce mean dose to larynx and parotid glands in comparison to postoperative radiation, which may result in lower toxicities. Clinical trials comparing primary CRT and primary surgery are warranted to compare patient toxicities.



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Original article
peer-reviewed

A Dosimetric Comparison of Primary Chemoradiation Versus Postoperative Radiation for Locally Advanced Oropharyngeal Cancer


Author Information

Stanley K. Woo

Department of Oncology, University of Alberta

Chad Freeman

Department of Oncology, University of Alberta

Brock J. Debenham Corresponding Author

Department of Oncology, University of Alberta


Ethics Statement and Conflict of Interest Disclosures

Human subjects: Consent was obtained by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Acknowledgements

We would like to thank Naomi Parker, Brian Chwyl, Kim Rans, Andree Desrochers, and Laura Grose for their help with this project.


Original article
peer-reviewed

A Dosimetric Comparison of Primary Chemoradiation Versus Postoperative Radiation for Locally Advanced Oropharyngeal Cancer


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Original article
peer-reviewed

A Dosimetric Comparison of Primary Chemoradiation Versus Postoperative Radiation for Locally Advanced Oropharyngeal Cancer

Stanley K. Woo">Stanley K. Woo, Chad Freeman">Chad Freeman, Brock J. Debenham">Brock J. Debenham

  • Author Information
    Stanley K. Woo

    Department of Oncology, University of Alberta

    Chad Freeman

    Department of Oncology, University of Alberta

    Brock J. Debenham Corresponding Author

    Department of Oncology, University of Alberta


    Ethics Statement and Conflict of Interest Disclosures

    Human subjects: Consent was obtained by all participants in this study. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

    Acknowledgements

    We would like to thank Naomi Parker, Brian Chwyl, Kim Rans, Andree Desrochers, and Laura Grose for their help with this project.


    Article Information

    Published: November 17, 2017

    DOI

    10.7759/cureus.1858

    Cite this article as:

    Woo S K, Freeman C, Debenham B J (November 17, 2017) A Dosimetric Comparison of Primary Chemoradiation Versus Postoperative Radiation for Locally Advanced Oropharyngeal Cancer. Cureus 9(11): e1858. doi:10.7759/cureus.1858

    Publication history

    Received by Cureus: October 31, 2017
    Peer review began: November 08, 2017
    Peer review concluded: November 14, 2017
    Published: November 17, 2017

    Copyright

    © Copyright 2017
    Woo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 3.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    License

    This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Introduction

Advanced-stage oropharyngeal cancer can be treated with primary chemoradiation (CRT) or primary surgery with adjuvant radiotherapy, both with similar survival outcomes. Though primary CRT prescribes a higher dose, adjuvant radiation requires irradiating the surgical bed, which may increase the high dose planned target volume (PTV). We hypothesize that the integral dose to the neck and dose to critical structures will be lower with primary CRT than adjuvant radiotherapy.

Methods

We selected the last 18 patients who underwent surgery and adjuvant radiotherapy at one institution between July 2015 and August 2016 with American Joint Committee on Cancer (AJCC) stage III or IVA oropharyngeal squamous cell cancer. Primary CRT treatment plans were created on the patients’ preoperative computed tomography (CT) scans and prescribed 70 Gy in 33 fractions, while postoperative plans were prescribed 60 Gy in 30 fractions. The radiation doses received by organs at risk for each primary CRT plan were compared to the corresponding adjuvant radiation plan.

Results

 Primary CRT plans had significantly smaller high dose PTV than adjuvant radiation plans (187.3 cc (95% CI 134.9-239.7) and 466.3 cc (95% CI 356.7-575.9), p<0.0001). The neck integral dose was lower in 14 of 18 plans using primary CRT, although this was not statistically significant (p=0.5375). The primary CRT plans had lower mean doses to ipsilateral (31.8 Gy (95% CI 27.5-36.0) vs 39.3 Gy (95% CI 35.4-43.1), p=0.0009)) and contralateral parotid glands (22.5 Gy (95% CI 22.1-22.8) vs 27.6 Gy (95% CI 23.4-31.8), p=0.0238) and larynx (20.7 Gy (95% CI 19.3-22.2) vs 40.2 Gy (95% CI 30.8-46.6), p<0.0001).

Conclusion

Primary CRT offered a decreased neck integral dose, though it was statistically insignificant. Primary CRT plans reduce mean dose to larynx and parotid glands in comparison to postoperative radiation, which may result in lower toxicities. Clinical trials comparing primary CRT and primary surgery are warranted to compare patient toxicities.



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Stanley K. Woo

Department of Oncology, University of Alberta

Chad Freeman

Department of Oncology, University of Alberta

Brock J. Debenham, Assistant Professor, M.D., F.R.C.P.C.

Department of Oncology, University of Alberta

For correspondence:
debenham@ualberta.ca

Stanley K. Woo

Department of Oncology, University of Alberta

Chad Freeman

Department of Oncology, University of Alberta

Brock J. Debenham, Assistant Professor, M.D., F.R.C.P.C.

Department of Oncology, University of Alberta

For correspondence:
debenham@ualberta.ca