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E. Dieleman
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MINI 37 - SCLC Therapy (ID 165)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Small Cell Lung Cancer
- Presentations: 1
- Moderators:D. Ettinger, G.R. Simon
- Coordinates: 9/09/2015, 18:30 - 20:00, 605+607
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MINI37.11 - Inter-Observer Variability in Hippocampus Delineation on MRI Scans for Hippocampal Avoidance Prophylactic Cranial Irradiation Trial (ID 2620)
18:30 - 20:00 | Author(s): E. Dieleman
- Abstract
- Presentation
Background:
Prophylactic cranial irradiation (PCI) is the standard treatment in patients with small-cell lung cancer (SCLC) without progression after chemo-radiotherapy in stage I-III disease and after having a remission after chemotherapy in stage IV. In an international phase III trial (NCT01780675), patients with SCLC are randomised to receive PCI with or without Hippocampal Avoidance (HA). Accurate delineation of the hippocampus is crucial for this trial. In this study we evaluate the hippocampus delineation variability among radiation oncologists in multi-institutions for SCLC patients.
Methods:
The left and right hippocampus from 5 randomly selected patients (10 structures) were delineated by 5 radiation oncologists and 2 neuroradiologist in 7 institutions according to the RTOG atlas (http://www.rtog.org/CoreLab/ContouringAtlases/HippocampalSparing.aspx), together with a questionnaire. For each patient, a high resolution 3D inversion recovery T1 weighted MRI-scan was first registered to the planning CT-scan (1mm slicing). The observer then delineated the hippocampus according to the atlas on axial slices of the MRI. The mapped delineations on the CT were then used in dose planning with a 5mm margin. The mean and standard deviation (SD) of 1) volume and 2) range in medio-lateral, superior-inferior and anterior-posterior directions were computed for each structure. The corresponding inter-observer reliability was estimated by the intra-class correlation coefficient (ICC absolute agreement) using a linear mixed model. A median surface was computed and the overall delineation variability per structure was calculated by the root-mean-square (rms) of the local SD per sampled points on the median surface, while the local SD corresponds to the perpendicular distance between each observer and a sampled point.
Results:
The standard deviation of the delineated volume per structure varied from 0.14 to 0.48cm3. The corresponding inter-observer reliability (ICC) was 0.19, implying a high variability among the observers. The overall delineation variability per structure varied from 0.6 to 1.0mm. Areas with good agreements were the superior and inferior part of the hippocampus. The difficult area (Fig.1) was in the anterior medial area, close to the amygdala and uncus. The ICC in medio-lateral, superior-inferior and anterior-posterior directions were 0.55, 0.64 and 0.80, respectively. A large spread of the SD of range in medio-lateral direction and the relative low ICC imply that a better instruction, or training is desirable to improve the delineations. Figure 1
Conclusion:
There was a substantial variability in hippocampus delineation among the observers. Stricter adherence to the RTOG guidelines and (web-based) training are needed. The implication of the variations on the dose distribution is currently verified.
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ORAL 20 - Chemoradiotherapy (ID 124)
- Event: WCLC 2015
- Type: Oral Session
- Track: Treatment of Locoregional Disease – NSCLC
- Presentations: 1
- Moderators:G. Blumenschein, J.Y. Chang
- Coordinates: 9/08/2015, 10:45 - 12:15, 201+203
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ORAL20.03 - Radiation Dose Escalation in Patients with Locally Advanced Non-Small Cell Lung Cancer; 60 Month Follow-Up of a Randomized Phase II Trial (ID 1190)
10:45 - 12:15 | Author(s): E. Dieleman
- Abstract
- Presentation
Background:
Concurrent chemoradiotherapy imposes beneficial effects on overall survival (OS) in patients with locally advanced non-small cell lung cancer (NSCLC). Nonetheless, the optimal radiation scheme still needs to be identified. The RTOG 0617 trial showed that patients receiving a high dose radiation scheme (37 x 2 Gy) had a significant shorter median OS (22.9 months) as compared to patients receiving a conventional 30 x 2 Gy radiation scheme (28.7 months). Dose escalation using hypo-fractionation however seems promising and might contribute to a better OS. We investigated long term OS in locally advanced NSCLC patients treated with concurrent chemoradiotherapy, using a hypo-fractionation scheme of 24 x 2.75 Gy +/- Cetuximab.
Methods:
A 2-armed phase II, multi-center study (NTR2230) was performed with the initial aim to assess the effect of the addition of Cetuximab to concurrent chemoradiotherapy in locally advanced NSCLC patients. Arm A received high dose radiotherapy (24 x 2.75 Gy) and concurrent daily low-dose cisplatin (6 mg/m[2]). Arm B received an identical treatment regimen with the addition of weekly Cetuximab (400 mg/m[2] loading dose one week prior to radiotherapy followed by weekly 250 mg/m[2]). Mortality follow-up information was completed until January 2015. Overall survival (OS) rates were calculated as time from randomization until death from any cause. Kaplan-Meier survival curves were plotted and 1-, 2- and 5-year OS proportions were calculated.
Results:
Between February 2009 and May 2011, 102 patients were randomly allocated in two arms; 51 patients (50%) in arm A and 51 patients (50%) in arm B. Follow-up information was available for 101 patients (99%). Median OS was 33.0 months (interquartile (IQ) range 20.0 to 46.0) and did not significantly differ between the two arms; 33.0 months (IQ-range 13.8 to 52.2) in Arm A and 30.0 months (IQ-range 15.3 to 44.7) in Arm B (Figure 1). 1-,2- and 5-year OS was 75.5%, 59.8% and 36.6%, respectively. Figure 1
Conclusion:
In this 2-armed phase II trial in NSCLC patients receiving concurrent chemoradiotherapy, the addition of Cetuximab to concurrent chemoradiotherapy did not improve 60-month OS in unselected patients with locally advanced NSCLC, in line with the RTOG 0617. However, the median OS was remarkably high when compared to the RTOG 0617: 30 and 33 months versus 23 and 29 months, respectively. Furthermore, 5-year OS was still 36.6%. Dose escalation using hypo-fractionation of 2.75 Gy per fraction might be one of the factors contributing to extended OS in patients with locally advanced NSCLC.
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