Author of

• 35188

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  P21 - Locoregional and Oligometastatic Disease - Treatment of Locally Advanced NSCLC (ID 131)

  • Event: WCLC 2020
  • Type: Posters
  • Track: Locoregional and Oligometastatic Disease
  • Presentations: 1
  • Moderators:
  • Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall

  • 35209

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    P21.15 - Sparing Preserved Lobes to Reduce Lung Dose for Operable IIIA NSCLC Patients Treated with Neoadjuvant Chemoradiotherapy (ID 2368)

    00:00 - 00:00  |  Presenting Author(s): Hengle Gu
    • Abstract
    • Slides

    Introduction
    

    For operable IIIa (N2) NSCLC patients, sparing lung irradiated dose in preoperative radiotherapy can reduce the incidence of radiation-induced lung injury and improve the efficacy of combined therapy.

    Comparing to protect the functional lung volume with SPECT lung perfusion image , reduce irradiation dose to the preserved lung lobes can simplify the treatment procedure, avoid the influence of multi-modality image registration error and no integrated definition of the functional lung contouring.

    Purpose of this study is to evaluate the effect of lobe-based lung sparing radiotherapy on target coverage and decrease of lung irradiation dose in radiotherapy followed by lobectomy, and establish a indicator to help doctors estimating which type of cases may benefit from this method.

    Methods
    

    41 IIIA pN2 non-small cell lung cancer cases were selected in this retrospective study.

    Target, total lung(minus GTV), tumor located lung lobe and other OARs were contoured

    2 IMRT plans were performed for each case, : one is conventional IMRT with total lung dose constraints，the other is a lobe-based IMRT with preserved lung lobes dose constraints. For all plans, 95% of the volume of PTV was covered by a 40Gy prescription dose.

    Dose-volume histogram (DVH) was used to assess dose distribution in target and OARs. Dose parameters of lung included V5, V10, V13, V15, V20 and mean lung dose(MLD) of ipsilateral lung, contralateral lung, total lung, resected lobe, preserved ipsilateral lung lobe and preserved total lung lobe.

    In addition, the correlation between tumor characteristics and lung dose parameters were analyzed.

    Results
    

    All plans met dose limits. Lobe-based IMRT significantly reduce the irradiated dose of Lung lobes, especially Preserved Total Lung and Preserved Ipsilateral Lung.

    For preserved total lung, V5, V10, V13, V15, V20 and MLD were decreased from 33.63 ± 12.3 Gy, 22.72 ± 7.22 Gy, 19.58 ± 6.29 Gy, 17.78 ± 5.78 Gy, 13.67 ± 4.73 Gy and 715.04 ± 227.34 Gy in conventional IMRT to 32.16±14.12 Gy, 18.32±6.56 Gy, 14.51±4.75 Gy, 12.74±4.05 Gy, 9.53±2.95 Gy and 608.2±201.23 Gy in lobe-based IMRT. The dose reduction of preserved ipsilateral lung is more significant.

    The dose of the lung lobe to be resected is increased only about 1%.

    The mean dose of Body decreased from 643.28±128.33cGy to 624.33±128.36 cGy

    Correlation of l/LoP-IL and lung dose indicates that patients with tumor in the lower and middle lobes may benefit from lobe-based IMRT.

    Conclusion
    

    For IIIa(N2)NSCLC patients treated with neoadjuvant radiotherapy , a lobe-based IMRT can effectively reduce the dose of the preserved lung lobe while ensuring the target coverage, which may lead to a reduction of of radiation pneumonitis incidence, especially in the mid-lower lobe where it is more difficult to control lung dose in conventional IMRT plan.

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