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Romaana Mir



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    FP04 - Locoregional and Oligometastatic Disease (ID 126)

    • Event: WCLC 2020
    • Type: Posters (Featured)
    • Track: Locoregional and Oligometastatic Disease
    • Presentations: 1
    • Moderators:
    • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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      FP04.02 - Feasibility of Radiotherapy Planning in the First 50 Patients Recruited to the ADSCaN Clinical Trial (ID 1884)

      00:00 - 00:00  |  Presenting Author(s): Romaana Mir

      • Abstract
      • Slides

      Introduction

      The ADSCaN clinical trial (ISRCTN47674500) randomizes patients with unresectable stage III NSCLC suitable for sequential chemo-radiotherapy to one of four accelerated dose-escalated experimental radiotherapy regimens (CHART-ED, IDEAL, I-START, and Isotoxic IMRT) or a standard radiotherapy regimen of 55Gy in 20 fractions. We present feasibility of radiotherapy planning in the first 50 patients.

      Methods

      ADSCaN was data locked and presented to the data monitoring committee (DMC) in November 2019. Dosimetric data: GTV volume (cc), PTV volume (cc), radiotherapy planning objectives, and dose to organs at risk (OAR) were recorded against the respective OAR constraints for each arm. Linear regression analysis examined the relationship between PTV volume and radiotherapy dose to the respective OAR. Adverse events (AEs) are reported for the first 50 patients.

      Results

      46 radiotherapy plans were available for review; 16 standard arm, 11 CHART-ED, 5 IDEAL, 7 I-START, and 7 Isotoxic IMRT. One of the first fifty recruited patients did not receive radiotherapy. Median GTV volume was 61.96 (cc) (IQR 36.22–91.41); median PTV volume was 285.86cc (IQR 216.65–385.45). The largest PTV volume was 1590.60cc. Radiotherapy delivery was 1-2 full arcs for 7 patients, 2-3 half arcs for 26 patients, and 4-7 static IMRT fields for 13 patients. PTV coverage achieved the mandatory planning objectives of V95% >90% and V90% >98% in all but one case in the I-START arm where the PTV spanned the hemi-thorax and mediastinum. The OAR constraints were achieved in all cases.

      Dose to respective OAR were plotted against PTV volume (figure); there was a positive correlation between lung and heart constraints and PTV volume. There was a negative correlation between PTV volume and D0.1cc oesophagus.

      dose to oar.jpg

      The strength of the correlation between PTV volume and OAR dose were weak to moderate: lung–GTV V20Gy R2=0.15944, D33% heart R2=0.14634, D67% heart R2=0.33828, D100% heart R2=0.58477, D0.1cc oesophagus R2=0.01195, indicating it is feasible to radically plan accelerated dose-escalated radiotherapy over a range of PTV and planning techniques. The overall CTCAE v4.0 grade 2 and 3 toxicity rate was 54% and 28%; specific grade 3 AE were dysphagia 2%, dyspnea 12%, fatigue 4%, oesophagitis 6%, pneumonitis 2%, and upper respiratory infection 2%. One patient developed bronchopneumonia as the sole grade 5 AE.

      Conclusion

      The recruiting ADSCaN clinical trial demonstrates feasibility of accelerated dose-escalated radiotherapy planning across treatment arms, dose objectives, and planning techniques, with no appreciable increase in AEs when compared to the contemporary NSCLC radical radiotherapy evidence base.

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