title: Effect of brain stem and dorsal vagus complex dosimetry on nausea and vomiting in head and neck intensity-modulated radiation therapy.
abstract: Intensity-modulated radiation therapy (IMRT) is becoming the treatment of choice for many head and neck cancer patients. IMRT reduces some toxicities by reducing radiation dose to uninvolved normal tissue near tumor targets; however, other tissues not irradiated using previous 3D techniques may receive clinically significant doses, causing undesirable side effects including nausea and vomiting (NV). Irradiation of the brainstem, and more specifically, the area postrema and dorsal vagal complex (DVC), has been linked to NV. We previously reported preliminary hypothesis-generating dose effects associated with NV in IMRT patients. The goal of this study is to relate brainstem dose to NV symptoms. We retrospectively studied 100 consecutive patients that were treated for oropharyngeal cancer with IMRT. We contoured the brainstem, area postrema, and DVC with the assistance of an expert diagnostic neuroradiologist. We correlated dosimetry for the 3 areas contoured with weekly NV rates during IMRT. NV rates were significantly higher for patients who received concurrent chemotherapy. Post hoc analysis demonstrated that chemoradiation cases exhibited a trend towards the same dose-response relationship with both brainstem mean dose (p = 0.0025) and area postrema mean dose (p = 0.004); however, both failed to meet statistical significance at the p ≤ 0.002 level. Duration of toxicity was also greater for chemoradiation patients, who averaged 3.3 weeks with reported Common Terminology Criteria for Adverse Events (CTC-AE), compared with an average of 2 weeks for definitive RT patients (p = 0.002). For definitive RT cases, no dose-response trend could be ascertained. The mean brainstem dose emerged as a key parameter of interest; however, no one dose parameter (mean/median/EUD) best correlated with NV. This study does not address extraneous factors that would affect NV incidence, including the use of antiemetics, nor chemotherapy dose schedule specifics before and during RT. A prospective study will be required to depict exactly how IMRT dose affects NV.
authors.affiliation: Department of Radiation Oncology, School of Health Sciences, Medical Dosimetry Program, Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Ciura
authors.forename: Michelle
authors.initials: M
authors.lastname: McBurney
authors.forename: Baongoc
authors.initials: B
authors.lastname: Nguyen
authors.forename: Mary
authors.initials: M
authors.lastname: Pham
authors.forename: Neal
authors.initials: N
authors.lastname: Rebueno
authors.forename: Clifton D
authors.initials: CD
authors.lastname: Fuller
authors.forename: Nandita
authors.initials: N
authors.lastname: Guha-Thakurta
authors.forename: David I
authors.initials: DI
authors.lastname: Rosenthal
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001933:Brain Stem / Q000528:radiation effects*; D015984:Causality; D015897:Comorbidity; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009325:Nausea / Q000453:epidemiology*; D009959:Oropharyngeal Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D015995:Prevalence; D011832:Radiation Injuries / Q000453:epidemiology*; D011874:Radiometry / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data; D020266:Radiotherapy, Conformal / Q000706:statistics & numerical data*; D018570:Risk Assessment; D012307:Risk Factors; D013781:Texas / Q000453:epidemiology; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000528:radiation effects*; D014839:Vomiting / Q000453:epidemiology*