Dataset Information

Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients.

ABSTRACT:

Objective

To investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas.

Materials and methods

Clinically delivered photon radiosurgery treatment plans were compared to five cochlear-optimized plans: one photon and four proton plans (total of 120). A 1x12 Gy dose was prescribed. Photon plans were generated with Precision (Cyberknife, Accuray) with no PTV margin for set-up errors. Proton plans were generated using an in-house automated multi-criterial planning system with three or nine-beam arrangements, and applying 0 or 3 mm robustness for set-up errors during plan optimization and evaluation (and 3 % range robustness). The sample size was calculated based on a reduction of cochlear Dmean > 1.5 Gy(RBE) from the clinical plans, and resulted in 24 patients.

Results

Compared to the clinical photon plans, a reduction of cochlear Dmean > 1.5 Gy(RBE) could be achieved in 11/24 cochlear-optimized photon plans, 4/24 and 6/24 cochlear-optimized proton plans without set-up robustness for three and nine-beam arrangement, respectively, and in 0/24 proton plans with set-up robustness. The cochlea could best be spared in cases with a distance between tumor and cochlea. Using nine proton beams resulted in a reduced dose to most organs at risk.

Conclusion

Cochlear dose reduction is possible in vestibular schwannoma radiosurgery while maintaining tumor coverage, especially when the tumor is not adjacent to the cochlea. With current set-up robustness, proton therapy is capable of providing lower dose to organs at risk located distant to the tumor, but not for organs adjacent to it. Consequently, photon plans provided better cochlear sparing than proton plans.

SUBMITTER: Koetsier KS

PROVIDER: S-EPMC10585330 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients.

Koetsier Kimberley S KS Oud Michelle M de Klerck Erik E Hensen Erik F EF van Vulpen Marco M van Linge Anne A Paul van Benthem Peter P Slagter Cleo C Habraken Steven J M SJM Hoogeman Mischa S MS Méndez Romero A A

Clinical and translational radiation oncology 20231007

<h4>Objective</h4>To investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas.<h4>Materials and methods</h4>Clinically delivered photon radiosurgery treatment plans were compared to five cochlear-optimized plans: one photon and four proton plans (total of 120). A 1x12 Gy dose was prescribed. Photon plans were generated with Precision (Cyberknife, Accuray) with no PTV margin for set-up errors. ...[more]

PMID: 37867612

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Project description:BackgroundThe management of vestibular schwannoma has evolved over the past hundred years. In the last decades, surgery has been gradually replaced by radiation therapy as a primary treatment modality, particularly for small tumors, due to the less invasive nature and the compared reported outcomes in tumor control and hearing preservation. However, irradiation sometimes fails to stop tumor growth. In a long-term follow-up after primary fractionated stereotactic radiotherapy, the rate of treatment failure was reported as 3% and needed surgical salvage. For single-fraction modality, Hasegawa et al. reported salvage treatment after primary Gamma Knife radiosurgery in 8%, where 90% of these underwent surgery and 50% of those who were treated with a second gamma knife surgery required surgical intervention later. An increase in tumor volume by more than 10-20%, tumor growth after three years, and no return to pretreatment volume after transient swelling have been considered as tumor recurrence rather than pseudoprogression, a transient increase in tumor volume after radiotherapy that occurs up to 30% of cases. It has been reported that microsurgery after radiotherapy is more difficult, with most authors reporting a loss of defined arachnoid planes and worse cranial nerve outcomes, especially for hearing and facial nerve function.Case descriptionA 43-year-old female patient was incidentally (asymptomatic) diagnosed on a magnetic resonance imaging (MRI) scan harboring a left vestibular schwannoma, grade T2 (Hannover classification), in 2015. Neurologic examination was unremarkable, and audiometry testing was normal. She was initially treated with observation. Three years later, in 2018, the lesion had enlarged, becoming a grade T3a and reaching the cistern of the cerebellopontine angle. The tumor was then treated with fractionated stereotactic radiosurgery (5 sessions of 5 Gy). MRI scans in 2019 and 2020 showed slight tumor growth. This enlargement was attributed to a pseudoprogression after radiosurgery, and only observation was advocated. In 2022, 4 years later, after radiosurgery, the tumor was still growing, and the patient began to suffer from hearing loss. A failure treatment was considered, and microsurgery was indicated. The patient was counseled about the risk of functional nerve impairment, and surgical consent was obtained. A retro sigmoid approach was planned. A gross total resection was attempted due to the clear subperineural plane during tumor dissection and because it was the only option that would provide a cure for the patient. The adjacent neurovascular structures were firmly adhered to the tumor capsule, which represented a major challenge for microdissection. The tumor was soft, without significant bleeding. A total resection was achieved, and the facial nerve was anatomically preserved. The patient developed facial paresis (House-Brackmann III) in the immediate postoperative period, which improved at the 6-month follow-up. Hearing loss did not improve. Postoperative MRI showed total resection.ConclusionMicrosurgery after radiotherapy for vestibular schwannoma is challenging in terms of indication, when to indicate, resection target, difficulty in dissection due to local changes, and outcome. Gross total resection may be considered, as it is the only treatment that may provide a cure for the patient. However, the patient should be counseled about the risks.

Project description:ImportanceManagement of sporadic vestibular schwannoma with radiosurgery is becoming increasingly common globally; however, limited data currently characterize patient outcomes in the setting of microsurgical salvage for radiosurgical failure.ObjectiveTo describe the clinical outcomes of salvage microsurgery following failed primary stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) among patients with sporadic vestibular schwannoma.Design, setting, and participantsThis was a cohort study of adults (≥18 years old) with sporadic vestibular schwannoma who underwent salvage microsurgery following failed primary SRS/FSRT in 7 vestibular schwannoma treatment centers across the US and Norway. Data collection was performed between July 2022 and January 2023, with data analysis performed between January and July 2023.ExposureSalvage microsurgical tumor resection.Main outcomes and measuresComposite outcome of undergoing less than gross total resection (GTR) or experiencing long-term facial paresis.ResultsAmong 126 patients, the median (IQR) age at time of salvage microsurgery was 62 (53-70) years, 69 (55%) were female, and 113 of 117 (97%) had tumors that extended into the cerebellopontine angle at time of salvage. Of 125 patients, 96 (76%) underwent primary gamma knife SRS, while 24 (19%) underwent linear accelerator-based SRS; the remaining patients underwent FSRT using other modalities. Postoperative cerebrospinal fluid leak was seen in 15 of 126 patients (12%), hydrocephalus in 8 (6%), symptomatic stroke in 7 (6%), and meningitis in 2 (2%). Each 1-mm increase in cerebellopontine angle tumor size was associated with a 13% increased likelihood of foregoing GTR (64 of 102 patients [63%]) or long-term postoperative House-Brackmann grade higher than I (48 of 102 patients [47%]) (odds ratio, 1.13; 95% CI, 1.04-1.23). Following salvage microsurgery, tumor growth-free survival rates at 1, 3, and 5 years were 97% (95% CI, 94%-100%), 93% (95% CI, 87%-99%), and 91% (95% CI, 84%-98%), respectively.ConclusionsIn this cohort study, more than half of patients who received salvage microsurgery following primary SRS/FSRT underwent less than GTR or experienced some degree of facial paresis long term. These data suggest that the cumulative risk of developing facial paresis following primary SRS/FSRT by the end of the patient's journey with treatment approximates 2.5% to 7.5% when using published primary SRS/FSRT long-term tumor control rates.

Project description:BackgroundHybrid proton-photon radiotherapy (RT) can provide better plan quality than proton or photon only RT, in terms of robustness of target coverage and sparing of organs-at-risk (OAR).PurposeThis work develops a hybrid treatment planning method that can optimize the number of proton and photon fractions as well as proton and photon plan variables, so that the hybrid plans can be clinically delivered day-to-day using either proton or photon machine.MethodsIn the new hybrid treatment planning method, the total dose distribution (sum of proton dose and photon dose) is optimized for robust target coverage and optimal OAR sparing, by jointly optimizing proton spots and photon fluences, while the target dose uniformity is also enforced individually on both proton dose and photon dose, so that the hybrid plans can be separately and robustly delivered on proton or photon machine. To ensure the target dose uniformity for proton and photon plans, the number of proton and photon fractions is explicitly modeled and optimized, so that the target dose for proton and photon dose components is constrained to be a constant fraction of the total prescription dose while the plan quality based on total dose is optimized. The feasibility of hybrid planning using the proposed method is validated with representative clinical cases including abdomen, lung, head-and-neck (HN), and brain.ResultsFor all cases, hybrid plans provided better overall plan quality and OAR sparing than proton-only or photon-only plans, better target dose uniformity and robustness than proton-only plans, quantified by treatment planning objectives and dosimetric parameters. Moreover, for HN and brain cases, hybrid plans also had better target coverage than photon-only plans.ConclusionsWe have developed a new hybrid treatment planning method that optimizes number of proton and photon fractions as well as proton spots and photon fluences, for generating hybrid plans that can be separately and robustly delivered on proton or photon machines. Preliminary results have demonstrated that hybrid plans generated by the new method have better plan quality than proton-only or photon-only plans.

Project description:ObjectiveRepeated controlled studies have revealed that stereotactic radiosurgery is better than microsurgery for patients with vestibular schwannoma (VS) <3 cm in need of intervention. In this systematic review we aimed to compare results from single-fraction stereotactic radiosurgery (SRS) to fractionated stereotactic radiotherapy (FSRT) for patients with VS.Data sources and eligibility criteriaWe systematically searched MEDLINE, Web of Science, Embase and Cochrane and screened relevant articles for references. Publications from 1995 through 2014 with a minimum of 50 adult (>18 years) patients with unilateral VS, followed for a median of >5 years, were eligible for inclusion. After screening titles and abstracts of the 1094 identified articles and systematically reviewing 98 of these articles, 19 were included.InterventionPatients with unilateral VS treated with radiosurgery were compared to patients treated with fractionated stereotactic radiotherapy.ResultsNo randomized controlled trial (RCT) was identified. None of the identified controlled studies comparing SRS with FSRT were eligible according to the inclusion criteria. Nineteen case series on SRS (n = 17) and FSRT (n = 2) were included in the systematic review. Loss of tumor control necessitating a new VS-targeted intervention was found in an average of 5.0% of the patients treated with SRS and in 4.8% treated with FSRT. Mean deterioration ratio for patients with serviceable hearing before treatment was 49% for SRS and 45% for FSRT, respectively. The risk for facial nerve deterioration was 3.6% for SRS and 11.2% for FSRT and for trigeminal nerve deterioration 6.0% for SRS and 8.4% for FSRT. Since these results were obtained from case series, a regular meta-analysis was not attempted.ConclusionSRS and FSRT are both noninvasive treatment alternatives for patients with VS with low rates of treatment failure in need of rescue therapy. In this selection of patients, the progression-free survival rates were on the order of 92-100% for both treatment options. There is a lack of high-quality studies comparing radiation therapy alternatives for patients with VS. Finally, 19 articles reported long-term tumor control after SRS, while only 2 articles reported long-term FSRT results, making effect estimates more uncertain for FSRT.

Project description:PurposeTo compare the dosimetric differences in stereotactic radiosurgery between use of passively scattered protons (PSRS) versus photons (XSRS) for pituitary adenomas.Methods and materialsNine patients with pituitary adenomas were selected among patients receiving single-fraction proton stereotactic radiosurgery (PSRS) between 2016 and 2017. These cases were replanned with XSRS using volumetric-modulated arc therapy with 2.5 mm and 5 mm multileaf collimators (2.5XSRS and 5XSRS, respectively). PSRS was planned with a dedicated single scattering stereotactic proton unit delivered via 3 equally or unequally weighted isocentric fields. XSRS plans were created with optimization to spare organs at risk. Plans were generated using the original total treatment dose delivered in 1 fraction.ResultsPlans were evaluated for target volume dosimetry and estimated clinical toxicity. There was no significant difference in clinical target volume V100%, V95%, V90% or homogeneity index between treatment modalities. PSRS offered lower maximum dose (Dmax) to organs at risk and equivalent uniform dose (EUD) compared with 5XSRS and 2.5XSRS, respectively, for critical structures including optic nerve (right, Dmax 4.18, 5.32, 5.41; EUD 3.35, 4.08, 4.20) and hypothalamus (Dmax 1.71, 3.94, 3.77; EUD 0.94, 2.47, 2.39; P < .05 for PSRS vs 5XSRS and 2.5XSRS). The projected risk of secondary tumors in excess of baseline was lowest for PSRS plans (PSRS 5.28, 5XSRS 12.93, 2.5XSRS 12.66 cases per 10,000 patient-years; P = .008 for PSRS vs 5XSRS, PSRS vs 2.5XSRS, and P = .77 for 5XSRS vs 2.5XSRS).ConclusionsWe demonstrate that neither modality has empirically superior dosimetry and identify potential clinical advantages as well as limitations of each technique. PSRS, 5XSRS and 2.5XSRS demonstrate comparable target volume dosimetry for pituitary adenoma. PSRS compared with XSRS modalities offers modestly decreased maximum dose and EUD to critical proximal structures and decreases risk of radiation-induced secondary tumors by more than half.

Dataset Information

Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients.

Objective

Materials and methods

Results

Conclusion

Publications

Cochlear-optimized treatment planning in photon and proton radiosurgery for vestibular schwannoma patients.

Similar Datasets

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