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S. Siva
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MA 17 - Locally Advanced NSCLC (ID 671)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Locally Advanced NSCLC
- Presentations: 1
- Moderators:S. Jheon, Georgios Stamatis
- Coordinates: 10/17/2017, 15:45 - 17:30, F203 + F204 (Annex Hall)
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MA 17.12 - Comparison of EORTC, PERCIST, PeterMac & Deauville PET Response Criteria after Radical ChemoRT in Non-Small-Cell Lung Cancer (ID 8169)
17:00 - 17:05 | Author(s): S. Siva
- Abstract
- Presentation
Background:
Response criteria for 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for thoracic malignancies include European Organization for Research and Treatment of Cancer (EORTC) criteria, Positron Emission tomography Response Criteria In Solid Tumors 1.0 (PERCIST), PeterMac Metabolic Visual Criteria and Deauville Criteria. It is unknown which criteria have the highest prognostic value in NSCLC.
Method:
Between 2004 and 2016, three NSCLC prospective trials included patients treated with radical radiotherapy (RT) or chemoRT with baseline and post-treatment FDG-PET imaging. For each patient, the four FDG-PET response criteria were reported retrospectively and blinded to outcome. Responses to therapy were categorized as complete metabolic response (CMR), partial metabolic response (PMR), stable metabolic disease (SMD) or progressive metabolic disease (PMD) and correlated with subsequent survival using Cox proportional hazard models, c-statistic, r[2] and Akaike information criterion (AIC).
Result:
Eighty-seven NSCLC patients underwent FDG-PET before and after radical RT (n=7) or chemoRT (n=80). Follow-up FDG-PET scans were performed at a median of 89 days (range 47-123 days) after RT. After a median follow-up of 49 months, median survival after PET response imaging was 28 months. Both qualitative response criteria (PeterMac and Deauville) showed perfect agreement (kappa = 1.0). Both semiquantitative criteria (EORTC and PERCIST) showed almost perfect agreement (kappa = 0.96). All four response criteria showed statistically significant associations with overall survival. The PeterMac and the Deauville criteria showed stronger survival associations (AIC=357.9) compared to EORTC (AIC=362.3) and PERCIST (AIC=362.6). The two qualitative criteria also performed better in the distinction between CMR and non-CMR (HR = 1.9, CI 1.0-3.4, p=0.047) versus EORTC (HR=1.2, CI 0.6-2.3, p=0.566) and PERCIST (HR 1.2, CI 0.6-2.3, p=0.548). Only 1, 4 and 6 patients had SMD in respectively PeterMac/Deauville, EORTC and PERCIST. Figure 1
Conclusion:
The visual PeterMac and Deauville criteria showed stronger predictive capacity than EORTC and PERCIST criteria, especially for distinguishing CMR from non-CMR.
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P1.14 - Radiotherapy (ID 700)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P1.14-017 - Impact of Systematic EBUS-TBNA Mediastinal Staging on Radical Radiotherapy Planning in NSCLC (ID 8497)
09:30 - 09:30 | Author(s): S. Siva
- Abstract
Background:
Radical radiotherapy often relies solely on radiological imaging to determine treatment volumes. Systematic mediastinal staging with endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) may identify PET-occult sites of mediastinal disease, or demonstrate benign causes for PET-positive LN. This study evaluated 1) Involved nodal coverage 2) Doses to organs-at-risk when planned based on PET-CT and EBUS-TBNA and 3) Incident dose to mediastinal nodes between 3D-CRT and Intensity-Modulated-Radiotherapy (IMRT).
Method:
Radical radiotherapy plans (60Gy/30 fractions) were created for patients with stage change following EBUS-TBNA from a prospective clinical trial. We compared lung Normal-Tissue-Complication-Probability (NTCP, pneumonitis), oesophageal and heart dose for planning to targets based on PET-CT versus PET-CT+EBUS-TBNA. The incidental dose to PET-negative/EBUS-TBNA-positive nodes from 3DCRT and IMRT was evaluated using volume receiving 35Gy as a surrogate for control of sub-clinical disease (Kepka, IJROBP, 73(5) 2009).
Result:
Of 30 patients enrolled, four were upstaged by EBUS-TBNA; these patients had a significant geographic miss of nodal GTV when planned to PET-positive nodes only (Figure 1). When planned based on PET-CT alone, the incidental dose to PET-negative/EBUS-TBNA-positive nodes was higher with IMRT for two patients (v35Gy increased by 17% & 6%; Figure 1a&b) and lower with IMRT (v35Gy reduced by 16% and 6%; Figure 1c&d) for two, dependent on nodal position relative to the primary. Six patients had negative pathology for PET avid nodal stations; Inclusion of EBUS-negative, PET-positive nodes resulted in an average increased lung NTCP of 5% (range 1%-13%), mean oesophagus dose of 13Gy (range 4-23Gy) and mean heart dose of 4Gy (range -0.1-11Gy) over plans based on EBUS-positive nodes alone. Figure 1
Conclusion:
Systematic EBUS-TBNA has the potential to improve loco-regional control and limit the probability of lung and heart toxicity. The incidental dose to adjacent tissue is inherently related to involved node/tumour position and not solely dictated by the radiation delivery technique.
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P2.14 - Radiotherapy (ID 715)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Radiotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P2.14-001 - Mid-Treatment Perfusion PET/CT Is More Effective Than Ventilation PET/CT in Functionally-Adapted Radiotherapy for NSCLC (ID 8508)
09:30 - 09:30 | Author(s): S. Siva
- Abstract
Background:
To assess the utility of four-dimensional (4D) ventilation/perfusion (V/Q) PET/CT lung imaging to facilitate mid-radiotherapy treatment adaption with volumetric modulated arc radiotherapy (VMAT).
Method:
In a prospective clinical trial, patients with non-small cell lung cancer (NSCLC) underwent [68]Ga-4D-V/Q PET/CT scanning before and during a six-week (60Gy) course of definitive chemoradiation. Functional lung volumes were delineated on both datasets as ‘highly perfused’ (HPLung) and ‘highly ventilated’ (HVLung), using a 70[th] centile SUV threshold. Three VMAT plans were created on the mid-treatment datatsets: optimised to anatomical lung, HPLung, and HVLung volumes, respectively. Functional dose volumetrics were assessed using the parameters of mean lung dose (MLD), and lung volume receiving 5, 20 or 30Gy, (V5, V20, and V30). Plan quality was assessed for consistency with respect to conformity indices, and doses to critical structures.
Result:
The study cohort consisted of 10 patients resulting in a total of 30 VMAT plans. PTV volumes reduced by a mean of 5.5% between scans. HVLung volume increased between scans by a median value of 39.2%. Subsequent volumetric and spatial changes were reflected in varying DICE similarity coefficients, or DSC (ranging from 0.336-0.923). HPLung decreased by a median value of 4.5% with spatial discrepancy represented by DSC of 0.568-0.805. Increase in ventilated function was most prevalent adjacent to the target, limiting the benefit of adaptive planning (Fig 1). Plan quality was consistent with the median PTV D95 ranging from 60.6-61.3Gy, and mean conformity index ranging from 1.23-1.25. Functional MLD of HPLung decreased by a mean of 7.3%, p=0.02. Plans optimised to HPLung resulted in a reduction of perfused lung V5 by a mean of 13.2%, p<0.01, with HVlung plans yielding a decrease in ventilated lung V5 of 9.6%, p=0.02. Fig 1 Figure 1
Conclusion:
To achieve reduced irradiation of functional lung, radiotherapy adaptation is more effectively facilitated by perfusion rather than ventilation imaging.
