Dataset Information

Outcomes and patterns of radiation associated brain image changes after proton therapy for head and neck skull base cancers.

ABSTRACT:

Background and purpose

To characterize patterns and outcomes of brain MR image changes after proton therapy (PT) for skull base head and neck cancer (HNC).

Material and methods

Post-treatment MRIs ≥6 months were reviewed for radiation-associated image changes (RAIC) in 127 patients. All patients had received at least a point dose of 40 Gy(RBE) to the brain. The MRIs were rigidly registered to planning CTs and RAIC lesions were contoured both on T1 weighted (post-contrast) and T2 weighted sequences, and dose-volume parameters extracted. Probability of RAIC was calculated using multistate survival analysis. Univariate/multivariate analyses were performed using Cox Regression. Recursive partitioning analysis was used to investigate dose-volume correlates of RAIC development.

Results

17.3% developed RAIC. All RAIC events were asymptomatic and occurred in the temporal lobe (14), frontal lobe (6) and cerebellum (2). The median volume of the contrast enhanced RAIC lesion was 0.5 cc at their maximum size. The RAIC resolved or improved in 45.5% of the patients and were stable or progressed in 36.4%. The 3-year actuarial rate of developing RAIC was 14.3%. RAIC was observed in 63% of patients when V_{67 Gy(RBE)} of the brain ≥0.17 cc.

Conclusion

Small RAIC lesions after PT occurred in 17.3% of the patients; the majority in nasopharyngeal or sinonasal cancer. The estimated dose-volume correlations confirm the importance of minimizing focal high doses to brain when achievable.

SUBMITTER: Engeseth GM

PROVIDER: S-EPMC7674217 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Publications

Outcomes and patterns of radiation associated brain image changes after proton therapy for head and neck skull base cancers.

Engeseth Grete May GM Stieb Sonja S Mohamed Abdallah Sherif Radwan ASR He Renjie R Stokkevåg Camilla Hanquist CH Brydøy Marianne M Fuller Clifton Dave CD Garden Adam S AS Rosenthal David I DI Phan Jack J Morrison William H WH Reddy Jay P JP Wu Richard R Zhang Xiaodong X Frank Steven Jay SJ Brandon Gunn Gary G

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 20200715

<h4>Background and purpose</h4>To characterize patterns and outcomes of brain MR image changes after proton therapy (PT) for skull base head and neck cancer (HNC).<h4>Material and methods</h4>Post-treatment MRIs ≥6 months were reviewed for radiation-associated image changes (RAIC) in 127 patients. All patients had received at least a point dose of 40 Gy(RBE) to the brain. The MRIs were rigidly registered to planning CTs and RAIC lesions were contoured both on T1 weighted (post-contrast) and T2 w ...[more]

PMID: 32679304

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Project description:PurposeTo 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 methodsMedical 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.ResultsBetween 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.ConclusionThe 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.

Project description:PurposeThe clinical advantage of intensity modulated proton therapy (IMPT) may be diminished by range and patient setup uncertainties. We evaluated the effectiveness of robust optimization that incorporates uncertainties into the treatment planning optimization algorithm for treatment of base of skull cancers.Methods and materialsWe compared 2 IMPT planning methods for 10 patients with base of skull chordomas and chondrosarcomas: (1) conventional optimization, in which uncertainties are dealt with by creating a planning target volume (PTV); and (2) robust optimization, in which uncertainties are dealt with by optimizing individual spot weights without a PTV. We calculated root-mean-square deviation doses (RMSDs) for every voxel to generate RMSD volume histograms (RVHs). The area under the RVH curve was used for relative comparison of the 2 methods' plan robustness. Potential benefits of robust planning, in terms of target dose coverage and homogeneity and sparing of organs at risk (OARs) were evaluated using established clinical metrics. Then the plan evaluation metrics were averaged and compared with 2-sided paired t tests. The impact of tumor volume on the effectiveness of robust optimization was also analyzed.ResultsRelative to conventionally optimized plans, robustly optimized plans were less sensitive for both targets and OARs. In the nominal scenario, robust and conventional optimization resulted in similar D95% doses (D95% clinical target volume [CTV]: 63.3 and 64.8 Gy relative biologic effectiveness [RBE]), P <.01]) and D5%-D95% (D5%-D95% CTV: 8.0 and 7.1 Gy[RBE], [P <.01); irradiation of OARs was less with robust optimization (brainstem V60: 0.076 vs 0.26 cm(3) [P <.01], left temporal lobe V70: 0.22 vs 0.41 cm(3), [P = .068], right temporal lobe V70: 0.016 vs 0.11 cm(3), [P = .096], left cochlea Dmean: 28.1 vs 30.1 Gy[RBE], [P = .023], right cochlea Dmean: 23.7 vs 25.2 Gy[RBE], [P = .059]). Results in the worst-case scenario were analogous.ConclusionsRobust optimization is effective for creating clinically feasible IMPT plans for tumors of the base of skull.

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Dataset Information

Outcomes and patterns of radiation associated brain image changes after proton therapy for head and neck skull base cancers.

Background and purpose

Material and methods

Results

Conclusion

Publications

Outcomes and patterns of radiation associated brain image changes after proton therapy for head and neck skull base cancers.

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