Dataset Information

Stereotactic body proton therapy for liver tumors: Dosimetric advantages and their radiobiological and clinical implications.

ABSTRACT:

Background and purpose

Photon Stereotactic Body Radiotherapy (SBRT) for primary and metastatic tumors of the liver is challenging for larger lesions. An in silico comparison of paired SBRT and Stereotactic Body Proton Therapy (SBPT) plans was performed to understand the potential advantages of SBPT as a function of tumor size and location.

Methods and materials

Theoretical tumor volumes with maximum diameter of 1-10?cm were contoured in the dome, right inferior, left medial, and central locations. SBRT and SBPT plans were generated to deliver 50?Gy in 5 fractions, max dose?<135%. When organs-at-risk (OAR) constraints were exceeded, hypothetical plans (not clinically acceptable) were generated for comparison. Liver normal tissue complication probability (NTCP) models were applied to evaluate differences between treatment modalities.

Results

SBRT and SBPT were able to meet target goals and OAR constraints for lesions up to 7?cm and 9?cm diameter, respectively. SBPT plans resulted in a higher integral gross target dose for all lesions up to 7?cm (mean dose 57.8?±?2.3?Gy to 64.1?±?2.2?Gy, p?p?p?ConclusionThe main advantages of SBPT over SBRT is meeting plan goals and constrains for larger targets, particularly dome and central locations, and sparing dose to uninvolved liver. For such patients, SBPT may allow improvements in tumor control and treatment safety.

SUBMITTER: Arscott WT

PROVIDER: S-EPMC7807648 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Publications

Stereotactic body proton therapy for liver tumors: Dosimetric advantages and their radiobiological and clinical implications.

Arscott W Tristram WT Thompson Reid F RF Yin Lingshu L Burgdorf Brendan B Kirk Maura M Ben-Josef Edgar E

Physics and imaging in radiation oncology 20181001

<h4>Background and purpose</h4>Photon Stereotactic Body Radiotherapy (SBRT) for primary and metastatic tumors of the liver is challenging for larger lesions. An <i>in silico</i> comparison of paired SBRT and Stereotactic Body Proton Therapy (SBPT) plans was performed to understand the potential advantages of SBPT as a function of tumor size and location.<h4>Methods and materials</h4>Theoretical tumor volumes with maximum diameter of 1-10 cm were contoured in the dome, right inferior, left medial ...[more]

PMID: 33458411

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Project description:Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose-response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to potentially improve both local tumor control and survival. Indeed, accurate knowledge of the relevant parameters describing tumor biology and normal tissue response is mandatory to correctly address this issue. In this context, the role of medical physicists and the AAPM in the development of radiobiological models is crucial for the progress of developing specific tool for radiobiological-based optimization treatment planning.

Project description:PurposeTo quantitatively evaluate published experiences with hepatic stereotactic body radiation therapy (SBRT), to determine local control rates after treatment of primary and metastatic liver tumors and to examine whether outcomes are affected by SBRT dosing regimen.Methods and materialsWe identified published articles that reported local control rates after SBRT for primary or metastatic liver tumors. Biologically effective doses (BEDs) were calculated for each dosing regimen using the linear-quadratic equation. We excluded series in which a wide range of BEDs was used. Individual lesion data for local control were extracted from actuarial survival curves, and data were aggregated to form a single dataset. Actuarial local control curves were generated using the Kaplan-Meier method after grouping lesions by disease type and BED (<100 Gy10 vs >100 Gy10). Comparisons were made using log-rank testing.ResultsThirteen articles met all inclusion criteria and formed the dataset for this analysis. The 1-, 2-, and 3-year actuarial local control rates after SBRT for primary liver tumors (n = 431) were 93%, 89%, and 86%, respectively. Lower 1- (90%), 2- (79%), and 3-year (76%) actuarial local control rates were observed for liver metastases (n = 290, log-rank P = .011). Among patients treated with SBRT for primary liver tumors, there was no evidence that local control is influenced by BED within the range of schedules used. For liver metastases, on the other hand, outcomes were significantly better for lesions treated with BEDs exceeding 100 Gy10 (3-year local control 93%) than for those treated with BEDs of ≤100 Gy10 (3-year local control 65%, P < .001).ConclusionsStereotactic body radiation therapy for primary liver tumors provides high rates of durable local control, with no clear evidence for a dose-response relationship among commonly utilized schedules. Excellent local control rates are also seen after SBRT for liver metastases when BEDs of >100 Gy10 are utilized.

Project description:We present our initial experience with CyberKnife stereotactic body radiation therapy (SBRT) in a heavily pretreated group of patients with liver metastases and primary liver tumors. From October 2007 to June 2009, 48 patients were treated at the Philadelphia CyberKnife Center for liver metastases or primary liver tumors. We report on 30 patients with 41 discrete lesions (1-4 tumors per patient) who received an ablative radiation dose (BED???79.2?Gy10?=?66?Gy EQD2). The treatment goal was to achieve a high SBRT dose to the liver tumor while sparing at least 700?cc of liver from radiation doses above 15?Gy. Twenty-three patients were treated with SBRT for metastatic cancer to the liver; the remainder (n?=?7) were primary liver tumors. Eighty-seven percent of patients had prior systemic chemotherapy with a median 24?months from diagnosis to SBRT; 37% had prior liver directed therapy. Local control was assessed for 28 patients (39 tumors) with 4?months or more follow-up. At a median follow-up of 22?months (range, 10-40?months), 14/39 (36%) tumors had documented local failure. A decrease in local failure was found with higher doses of SBRT (p?=?0.0237); 55% of tumors receiving a BED???100?Gy10 (10/18) had local failure compared with 19% receiving a BED?>?100?Gy10 (4/21). The 2-year actuarial rate of local control for tumors treated with BED?>?100?Gy10 was 75% compared to 38% for those patients treated with BED???100?Gy10 (p?=?0.04). At last follow-up, 22/30 patients (73%) had distant progression of disease. Overall, seven patients remain alive with a median survival of 20?months from treatment and 57?months from diagnosis. To date, no patient experienced persistent or severe adverse effects. Despite the heavy pretreatment of these patients, SBRT was well tolerated with excellent local control rates when adequate doses (BED?>?100?Gy10) were used. Median survival was limited secondary to development of further metastatic disease in the majority of patients.

Dataset Information

Stereotactic body proton therapy for liver tumors: Dosimetric advantages and their radiobiological and clinical implications.

Background and purpose

Methods and materials

Results

Publications

Stereotactic body proton therapy for liver tumors: Dosimetric advantages and their radiobiological and clinical implications.

Similar Datasets

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