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Changhui Yu



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    P1.17 - Treatment of Locoregional Disease - NSCLC (Not CME Accredited Session) (ID 949)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 2
    • Moderators:
    • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
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      P1.17-09 - V30 May Better Predict Radiation Pneumonitis After Intensity-Modulated Radiation Therapy for Lung Cancer (ID 13780)

      16:45 - 18:00  |  Author(s): Changhui Yu

      • Abstract
      • Slides

      Background

      V20 and MLD are the most commonly used dose constraints for radiation pneumonitis (RP) prediction. However, intensity-modulated radiation therapy (IMRT) has unrestricted beam arrangements, an infinite number of very different dose distributions could be generated in the lung volume outside the planning target volume (PTV). Conventional dose constraints from traditional 3D conformal RT may not be valid for IMRT treatment. We hypothesize that lung dosimetric parameters may have different RP predictive values from that of traditional constraints (largely generated from 3D treatment) in IMRT treated lung cancer patients.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We retrospectively enrolled184 IMRT treated lung cancer patients from January 2014 to October 2017. The primary endpoint was acute grade 2 or higher symptomatic radiation pneumonitis (RP2), based on the National Cancer Institute’s Common Terminology Criteria for Adverse Events (version 4.03). Vdose (from V5 to V50) and MLD were generated from the lung volume outside PTV. Univariate and multivariate logistic regression analysis was used to evaluate the association between the dose parameters outside PTV to RP2. We employed area under the curve (AUC) for the receiver operating characteristic curve (ROC) to assess prediction accuracy for the single or multi-variate model.

      4c3880bb027f159e801041b1021e88e8 Result

      26 out of 184 lung cancer patients (14.1%) developed RP2 within 3 months after the end of IMRT treatment. In univariate logistic regression, although none of the clinical parameters was significantly associated with RP2, female gender (P=0.051) and chemotherapy (P=0.151) had a trend of correlation. V5 (P=0.007), V10(P=0.012) V20 (P=0.004), V30 (P=0.003) and MLD (P=0.004) were significantly associated with RP2 incidence. From ROC curve, the largest AUC of 0.67 was generated from V30, which showed a better predictive value compared with other dosimetric factors. Multivariate logistic regression analysis showed the only significant dosimetric factor is V30 (P=0.021). Combining gender and chemotherapy factors, V30 has an AUC of 0.71 which is the largest among all the other dosimetric factors.

      8eea62084ca7e541d918e823422bd82e Conclusion

      For IMRT treated lung cancer patients, V30 generated from lung volume outside PTV may predict RP more accurately than traditional dosimetric parameters.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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      P1.17-20 - Excluding PTV From Lung Volume May Better Predict Radiation Pneumonitis For IMRT Treated Lung Cancer Patients (ID 12051)

      16:45 - 18:00  |  Author(s): Changhui Yu

      • Abstract
      • Slides

      Background

      Lung dose-volume histogram(DVH) could be calculated from multiple normal lung definitions. These dose differences have a direct impact on lung cancer radiotherapy treatment planning. Earlier study from 3D conformal radiation therapy suggested dose computation from total normal lung excluding gross tumor volume (GTV) may be more accurate than that of excluding planning target volume (PTV). It is unclear which definition should be used to more accurately predict radiation pneumonitis (RP) in lung cancer patients treated with intensity-modulated radiation therapy (IMRT). We aim to determine a superior normal lung volume to more accurately predict symptomatic RP in lung cancer patients treated with IMRT.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      This is a retrospective study. All patients treated with IMRT with at least 3 months follow-up are eligible. The normal lungs are defined by total lung volume excluding GTV, PTV or directly using the total lung volume. V5, V20, and MLD have been extracted for all three definitions. RP was diagnosed and graded according to the National Cancer Institute’s Common Terminology Criteria for Adverse Events, version 4.03. The primary endpoint was grade 2 or higher RP (RP2). Correlation between RP2 and dose parameters were analyzed by logistic regression. We compared RP prediction performance of each lung volume using area under the receiver operating characteristic curve (AUC).

      4c3880bb027f159e801041b1021e88e8 Result

      A total of 184 consecutive patients treated between January 2014 and October 2017 were eligible, 26 patients (14%) developed RP2 within 3 months after treatment. Significant dosimetric difference was found between any 2-paired lung volumes (Ps<0.0001). All dose parameters from Lung-PTV method had significant correlation with RP2, with greater AUCs than the other two definitions. The best RP prediction performance was found in Lung-PTV volume MLD (AUC=0.649), which is significantly better than Lung-GTV volume MLD (AUC=0.611, P=0.006).

      8eea62084ca7e541d918e823422bd82e Conclusion

      There were significant dosimetric differences from various normal lung definitions. Excluding PTV method may accurately predict acute symptomatic radiation pneumonitis for IMRT treated lung cancer patients.

      6f8b794f3246b0c1e1780bb4d4d5dc53

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