Head and Neck Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_34_2785 - Investigation of the three-dimensional dose distribution of mandibular areas of origin of advanced osteoradionecrosis in oropharyngeal cancer patients receiving IMRT

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Investigation of the three-dimensional dose distribution of mandibular areas of origin of advanced osteoradionecrosis in oropharyngeal cancer patients receiving IMRT
A. S. Mohamed1,2, K. A. Al Feghali3, S. P. Ng2, H. Elhalawani3, K. A. Hutcheson2, M. S. Chambers2, J. Phan4, J. Kraeima5, H. Glas5, M. Witjes5, G. B. Gunn2, A. S. Garden2, D. I. Rosenthal2, S. J. Frank2, W. H. Morrison2, C. D. Fuller6, and S. Lai2; 1Clinical Oncology and Nuclear Medicine Department, Alexandria University, Alexandria, Egypt, 2The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, 4Dept. of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 5University of Groningen, Groningen, Netherlands, 6University of Texas Graduate School of Biomedical Sciences, Houston, TX

Purpose/Objective(s): Recent data demonstrated that a wide range of two-dimensional dose-volume parameters in the intermediate and high dose beam-path are associated with the development of osteoradionecrosis (ORN) in patients with oropharyngeal carcinoma (OPC) treated with intensity-modulated radiation therapy (IMRT). We aim to validate these findings by determining the three-dimensional (3-D) spatial dose distribution of the mandibular area of ORN origin.

Materials/Methods: Subsequent to institutional review board (IRB) approval, we identified patients with grade IV ORN requiring major surgery among patients with OPC treated with IMRT between 2002 and 2013. The initial computed tomography (CT) scans documenting the diagnosis of ORN were identified. The mandibular areas affected with ORN were manually segmented for all patients to create 3-D ORN volume of interest (ORN-VOI). Planning CTs and dose grids were subsequently retrieved. ORN-depicting CT scans were then co-registered to planning CT scans using a validated commercial image registration software (Velocity AI 3.0.1, Atlanta, GA). Finally, ORN-VOIs were mapped to planning CT scans, and dose grid then dosimetric parameters were extracted for each VOI.

Results: Among 1500 patients reviewed, twenty-five patients (1.7%) with grade IV ORN were identified. Median follow-up was 76 months (range 24-183) and median time to development of ORN was 22 months (range 5-132). Median age at diagnosis was 61 years (range 47-72), and 84% were men. The site of tumor origin was base of tongue, tonsil, and posterior pharyngeal wall in 12, 12, and 1 patient(s), respectively. Median radiation prescription dose was 70 Gy in 33 fractions. Only two patients developed ORN contralateral to the tumor site. The average of minimum dose to ORN-VOIs (i.e. the isodose line that covers 100% of the ORN volume) was 54.3 Gy. The first, second, third, and fourth quartile minimum dose distribution for ORN-VOI ranged from 32.4-46.7, 46.7-54.6, 54.6-64.6, and 64.6-68.5 Gy, respectively. The averages of mean and maximum doses to ORN VOIs were 66.3 Gy (range 54-75) and 72.5 Gy (range 64-78), respectively.

Conclusion: The mandibular areas of origin of advanced ORN in OPC patients treated with IMRT received at least 55 Gy in approximately half of the examined cohort. However, lower doses, in the intermediate dose range (32-55 Gy), were also associated with mandibular ORN. Our findings suggest that the intermediate dose beam-path results in long-term bone toxicity for OPC survivors.

Author Disclosure: A.S. Mohamed: Research Grant; NIH/NIDCR. K.A. Al Feghali: None. S. Ng: Employee; The University of Texas MD Anderson Cancer Center. H. Elhalawani: None. K.A. Hutcheson: None. J. Phan: None. J. Kraeima: None. M. Witjes: None. G.B. Gunn: Associate Medical Director; MD Anderson Cancer Center - Proton Therapy. A.S. Garden: None. S.J. Frank: Research Grant; C4 Imaging, ELEKTA, U19. Founder and Director; C4 Imaging. Honoraria; ELEKTA, Varian Medican Systems, Inc. Advisory Board; Varian Medican Systems, Inc. Stock; C4 Imaging. Royalty; C4 Imaging. Patent/License Fees/Copyright; C4 Imaging. Chairman; American Brachytherapy Society. Director; C4 Imaging. Director-at-large; North America Skull Base Society. W.H. Morrison: Advisory Board; Regeneron. Stock; Merck, Baxter, Johnson and Johnson. Member; NCCN Nonmelanoma Skin and Merkel Cell Committees. C.D. Fuller: Research Grant; National Institutes of Health, National Science Foundation, Elekta AB. Grant funding; Elekta AB. Honoraria; Nederlandse Organisatie voor Wetenschappelijk Onde. Consultant; Elekta AB, Nederlandse Organisatie voor Wetenschappelijk Onde. Travel Expenses; Elekta AB, Nederlandse Organisatie voor Wetenschappelijk Onde. Reviewer; Radiological Society of North America. Associate Editor; Radiographics. Data Management Task Force Committee Member; MR-LinAc Consortium. Member; National Cancer Institute. Task Group Member; American Association of Physicists in Medicine. S. Lai: Research Grant; NIDCR.

Abdallah Mohamed, MD

MD Anderson Cancer Center

Biography:
Abdallah Sherif Radwan Mohamed, MD, MSc. Research Scientist, MD Anderson Cancer Center. My research long-term goal is to develop novel bio-imaging based platforms that allow for biologically-modulated adaptive radiation therapy for future personalized radiation therapy applications. This involves the integration of multimodality imaging methodologies, biomarkers identification and characterization, imaging-guided dose-response assessment for tumor and normal tissues, multimodality image registration, adaptive therapy planning, patterns of failure characterization and oncologic outcomes correlation. My research efforts have resulted in several contributions to science, specifically in the fields of image registration, segmentation, quality assurance, radiation planning margin assessment for radiotherapy planning purposes, radiotherapy-associated toxicity, patterns of failures, and clinical outcomes assessment, as well as imaging biomarker development.

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