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S. Siva
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MINI 20 - Surgery (ID 137)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
- Moderators:G. Veronesi, R. Flores
- Coordinates: 9/08/2015, 16:45 - 18:15, 201+203
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MINI20.13 - A Prospective Comparison of FDG-PET & EBUS for Determining the Extent of Mediastinal Lymph Node Involvement in NSCLC (ID 2323)
17:55 - 18:00 | Author(s): S. Siva
- Abstract
- Presentation
Background:
Non-small cell lung cancer (NSCLC) may be treated with curative intent using radiotherapy, either as single modality or in combination with systemic chemotherapy. Most commonly, radiation treatment is planned based on findings at 18-Fluorodeoxyglucose Positron Emission Tomography (PET), following pathologic confirmation of involvement at a single mediastinal site. We hypothesized that systematic mediastinal evaluation with EBUS-TBNA in NSCLC patients considered for radical radiation therapy may identify disease extent discrepant with that indicated by PET-CT.
Methods:
This prospective ethics board-approved multi-centre cohort study in three Austrailan tertiary centres consented patients prior to mediastinal evaluation with Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) for NSCLC,where non-invasive imaging indicated the likely treatment modality would include radical radiotherapy. EBUS evaluation was performed systematically with sampling of any lymph node (LN) exceeding 6mm diameter.
Results:
Thirty eligible patients with NSCLC form the basis of this report. No procedural complications occurred during performance of EBUS-TBNA. LN sampling was performed from a mean 2.5 lymph node stations per patient (median 3,range 1–5). Adequate samples were obtained from all sites examined by EBUS-TBNA. Mean long-axis size of sampled LN was 16+7.8mm (median 13mm,range 5–36mm). 24% of sampled LN were 10mm or less. Discordant findings were observed in 10 of 30 patients (33%) (Figure 1) EBUS-TBNA identified a greater extent of mediastinal involvement than PET in four patients, with invasive sampling resulting in upstaging in three patients. In one further patient, extent of disease was greater than noted on PET due to more proximal involvement of LN disease not resulting in stage advancement. Median size of LN upstaged by EBUS was 7.5mm (range 7–9). In eleven mediastinal LN in six patients, EBUS identified a lesser extent of mediastinal disease than PET, including two patients down-staged from N3 à N2. Median size of LN down-staged by EBUS was 12mm (range 6–21). FIGURE 1. Flowchart of patients Figure 1
Conclusion:
Our findings demonstrate clinically significant discrepancy between two modalities frequently used to stage mediastinal disease extent in NSCLC patients being considered for radiotherapy. PET-based radiotherapy planning alone may not be appropriate given the risk of excessively large, or insufficiently large, radiation fields where planning is not based on invasive LN sampling. These results suggest minimally invasive comprehensive/systematic mediastinal staging should be considered for all patients prior to radiotherapy to accurately assess pathologic stage and extent of disease, and to ensure treatment fields most accurately encompass all sites of disease.
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ORAL 36 - Translational Science/Radiation (ID 151)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
- Moderators:E. Vokes, B. Kavanagh
- Coordinates: 9/09/2015, 16:45 - 18:15, Mile High Ballroom 2c-3c
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ORAL36.06 - 4D-VQ-PET/CT Imaging Allows Strong Correlation Between Radiotherapy Dose and Change in Lung Ventilation, Perfusion and Density (ID 211)
17:39 - 17:50 | Author(s): S. Siva
- Abstract
- Presentation
Background:
[68]Ga-V/Q PET/CT is a novel imaging modality for assessment of perfusion(Q), ventilation(V) and lung density changes in the context of radiotherapy (RT) for non-small cell lung cancer.
Methods:
In a prospective clinical trial, 20 patients underwent 4D-V/Q PET/CT before treatment, 4 weeks into treatment and 3 months after definitive lung RT. Eligible patients were prescribed 60 Gy in 30 fractions with or without concurrent chemotherapy. Functional images were registered to the RT planning 4D-CT and isodose volumes averaged into 10 Gy bins. Within each dose bin, relative loss in SUV was recorded for ventilation and perfusion, and loss in air-filled fraction was recorded to assess RT-induced lung fibrosis. A dose-effect relationship was described using both linear and 2-parameter logistic fit models and goodness of fit assessed using Akaike Information Criterion (AIC).
Results:
A total of 179 imaging datasets were available for analysis (1 scan unrecoverable). An almost perfectly linear dose-response relationship was observed for perfusion and air-filled fraction (r[2] = 0.99, p < 0.01), with ventilation also strongly linear (r[2] = 0.95, p < 0.01) [Figure]. Logistic models did not provide a better fit as evaluated by AIC [Table]. Perfusion, ventilation and the air-filled fraction changed by -7.5% ± 0.3%, -7.1% ± 0.6% and 4.9% ± 0.02% per 10 Gy, respectively. Within high-dose regions, higher baseline SUV was associated with greater rate of loss. At 50Gy and 60Gy the rate of loss was 1.35% (p = 0.07) and 1.73% (p = 0.05) per SUV, respectively. Of 8/20 patients with peri-tumoral reperfusion / re-ventilation during treatment, 7/8 did not sustain this effect post-treatment. Figure 1 Figure 2
Conclusion:
RT induced regional lung functional deficits occur in a dose dependent manner and can be estimated using simple linear models with 4D-V/Q PET/CT imaging. These findings may inform functional lung sparing by planning RT using this novel imaging technology.
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P2.01 - Poster Session/ Treatment of Advanced Diseases – NSCLC (ID 207)
- Event: WCLC 2015
- Type: Poster
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.01-043 - Lung Cancer Radiotherapy - Current Patterns of Practice in Australia and New Zealand (ID 801)
09:30 - 09:30 | Author(s): S. Siva
- Abstract
Background:
The RANZCR Faculty of Radiation Oncology Lung Interest Cooperative (FROLIC) surveyed patterns of lung cancer radiotherapy practice in Australasia for both non-small cell (NSCLC)and small cell lung (SCLC) cancer to evaluate current patterns of care and define gaps in optimal care requiring improvement.
Methods:
Radiation Oncologists were surveyed at all 62 departments in Australasia using a web-based survey targeting those treating lung cancer. Questions covered current radiotherapy practice as well as measures of quality
Results:
Of 62 responses received, 57 did treat lung cancer and were eligible for analysis. All Australian states and New Zealand were represented. Sixty-two percent of respondents worked at metropolitan centres, 58% were subspecialists in lung cancer and 60% participate in lung cancer trials. Ninety-four percent discuss lung cancer patients at a tumour board, 74% peer review contours for conventional fractionation and 50% for SABR. Fifty percent used a department protocol for contouring and/or prescription, 39%, an external protocol and 11% had no protocol. For radical conventional radiotherapy, 58% use 4DCT to assess tumour motion, 44% utilise breath hold or respiratory gating, 44% use PET Fusion, 35%, free-breathing CT and 23% PET-CT simulation. In palliative settings, free-breathing CT was most common (81%). For conventional treatment, 98% use 3DCRT, 34% IMRT and 18% VMAT. Image verification was primarily with cone beam CT (86%), KV imaging (72%) and MV imaging (30%). The commonest dose fractionation regime in NSCLC was 60Gy in 30 fractions used in 95% of node-positive and 82% of node-negative disease. 66Gy in 33 fractions and 50-55Gy in 20 had been used by 32% and 30%of respondents respectively. 30Gy/10 fractions was the most frequent palliative regime that had been used (by 76%), followed by 36Gy/12 (72%) . For limited stage SCLC, the majority (61%) treated with 45-50.4Gy in 25-28 fractions while 45Gy/30 twice daily had been used by 48%. In extensive stage SCLC, consolidation chest radiotherapy was used by 63% in complete response, 48% for partial response and 24% would not treat. 46% of departments provided SABR but only half treated central tumours. For peripheral tumours, 80% used 54Gy in 3 fractions and if close to chest wall, 70% used 48Gy in 4 fractions. In fit patients with synchronous solitary brain metastasis and controlled extra-thoracic disease, 37% of respondents would treat both chest and brain definitively, 43% would do so only if chest disease was equivalent to Stage I/II, and 9% would never treat radically. If three brain metastases were present, just 46% would treat definitively. In the setting of an isolated systemic metastasis only, 35% would treat definitively while 61% do not offer definitive treatment in the setting of systemic oligo-metastases.
Conclusion:
A significant proportion of radiation oncologists did not have access to 4DCT for simulation. The majority used 3D image verification and consistently prescribed evidence-based doses. Although protocols were widely used, a significant number did not participate in peer review of contours. The treatment of synchronous oligo-metastatic disease was variable, likely due to a lack of high quality evidence and should be an area of future research.
