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ABSTRACT: Purpose
To demonstrate temporal lobe necrosis (TLN) rate and clinical/dose-volume factors associated with TLN in radiation-naïve patients with head and neck cancer treated with proton therapy where the field of radiation involved the skull base.Materials and methods
Medical records and dosimetric data for radiation-naïve patients with head and neck cancer receiving proton therapy to the skull base were retrospectively reviewed. Patients with <3 months of follow-up, receiving <45 GyRBE or nonconventional fractionation, and/or no follow-up magnetic resonance imaging (MRI) were excluded. TLN was determined using MRI and graded using Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Clinical (gender, age, comorbidities, concurrent chemotherapy, smoking, radiation techniques) and dose-volume parameters were analyzed for TLN correlation. The receiver operating characteristic curve and area under the curve (AUC) were performed to determine the cutoff points of significant dose-volume parameters.Results
Between 2013 and 2019, 234 patients were included. The median follow-up time was 22.5 months (range = 3.2-69.3). Overall TLN rates of any grade, ≥ grade 2, and ≥ grade 3 were 5.6% (N = 13), 2.1%, and 0.9%, respectively. The estimated 2-year TLN rate was 4.6%, and the 2-year rate of any brain necrosis was 6.8%. The median time to TLN was 20.9 months from proton completion. Absolute volume receiving 40, 50, 60, and 70 GyRBE (absolute volume [aV]); mean and maximum dose received by the temporal lobe; and dose to the 0.5, 1, and 2 cm3 volume receiving the maximum dose (D0.5cm3, D1cm3, and D2cm3, respectively) of the temporal lobe were associated with greater TLN risk while clinical parameters showed no correlation. Among volume parameters, aV50 gave maximum AUC (0.921), and D2cm3 gave the highest AUC (0.935) among dose parameters. The 11-cm3 cutoff value for aV50 and 62 GyRBE for D2cm3 showed maximum specificity and sensitivity.Conclusion
The estimated 2-year TLN rate was 4.6% with a low rate of toxicities ≥grade 3; aV50 ≤11 cm3, D2cm3 ≤62 GyRBE and other cutoff values are suggested as constraints in proton therapy planning to minimize the risk of any grade TLN. Patients whose temporal lobe(s) unavoidably receive higher doses than these thresholds should be carefully followed with MRI after proton therapy.
SUBMITTER: Kitpanit S
PROVIDER: S-EPMC7302730 | biostudies-literature | 2020
REPOSITORIES: biostudies-literature
Kitpanit Sarin S Lee Anna A Pitter Ken L KL Fan Dan D Chow James C H JCH Neal Brian B Han Zhiqiang Z Fox Pamela P Sine Kevin K Mah Dennis D Dunn Lara A LA Sherman Eric J EJ Michel Loren L Ganly Ian I Wong Richard J RJ Boyle Jay O JO Cohen Marc A MA Singh Bhuvanesh B Brennan Cameron W CW Gavrilovic Igor T IT Hatzoglou Vaios V O'Malley Bernard B Zakeri Kaveh K Yu Yao Y Chen Linda L Gelblum Daphna Y DY Kang Jung Julie JJ McBride Sean M SM Tsai Chiaojung J CJ Riaz Nadeem N Lee Nancy Y NY
International journal of particle therapy 20200528 4
<h4>Purpose</h4>To demonstrate temporal lobe necrosis (TLN) rate and clinical/dose-volume factors associated with TLN in radiation-naïve patients with head and neck cancer treated with proton therapy where the field of radiation involved the skull base.<h4>Materials and methods</h4>Medical records and dosimetric data for radiation-naïve patients with head and neck cancer receiving proton therapy to the skull base were retrospectively reviewed. Patients with <3 months of follow-up, receiving <45 ...[more]