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Yaping Xu



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    P2.01 - Advanced NSCLC (ID 159)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Advanced NSCLC
    • Presentations: 2
    • Now Available
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.01-89 - Feasibility of Individualized Multidisciplinary Treatment for Locally Advanced Non-Small Cell Lung Cancer Based on the Treatment Planning (Now Available) (ID 2032)

      10:15 - 18:15  |  Presenting Author(s): Yaping Xu

      • Abstract
      • Slides

      Background

      In the individualized multidisciplinary treatment of patients with locally advanced non-small cell lung cancer (LANSCLC), the feasibility of dose escalation to the patients with sequential chemoradiotherapy for increasing tumor control and dose reduction to the patients with concurrent chemoradiotherapy for mitigating the side effects of radiotherapy was analyzed in the aspect of treatment plan optimization.

      Method

      Fifty patients with LANSCLC were randomly chosen from Shanghai Pulmonary Hospital and treatment plans were replanned. These patients’ PTV was defined as CTV+0.4cm, and CTV was the extravasation of 0.6-0.8cm of GTV, at least 95% volume of the PTV receive 60Gy/30fx, and these plans were called control group. The initial GTV was taken as GTV1, and GTV2 was obtained after GTV irradiated 40Gy; PTV1 was defined as GTV1+0.4cm, and PTV2 was defined as GTV2+0.4cm. With PTV2 dose escalated, the plans with lung remaining the same dose as control group were the Test1 group, and the plans with PTV1 receiving 60Gy and PTV receiving 45Gy were the Test2 group. The feasibility of the treatment regimen for Test1 Group and Test2 Group was analyzed from the perspective of dose drop gradient and the sparing of OARs, respectively.

      Result

      By comparing Test1 group with control group, it is found that the dose PTV2 received is affected greatly by the volume ratio, VPTV-PTV1/VPTV, which will escalate when VPTV-PTV1/VPTV increases. When VPTV-PTV1/VPTV is in these range, 0.2~0.3, 0.3~0.35, 0.35~0.4, 0.4~0.45, then the dose escalated for PTV2 will be 63Gy, 66Gy, 69Gy and 72Gy. And by comparing Test2 group with control group, it is found that the dose received by OARs will be reduced in Test2 group, for example, V5, V20, V30 and MLD for lung will decrease 2.17%±1.2792%, 1.7148%±1.04733%, 1.9982%±1.165%, 1.299Gy±0.564Gy, respectively; V50 and MHD for heart will decrease 1.9128%±2.1184%, 1.229Gy±0.921Gy, respectively; V60, Dmax and MED for esophagus will decrease 5.41%±5.91%, 4.6296Gy±4.4479Gy, 2.3491Gy±1.3411Gy, respectively, and all the p values are far less than 0.05.

      Conclusion

      Individualized radiotherapy can be performed on LANSCLC, and VPTV-PTV1/VPTV can be used to predict the dose drop gradient. In Test1 group, considering not add additional dose to lung, the larger VPTV-PTV1/VPTV, the higher the PTV2 can escalate. In test2 group, reducing the initial irradiation-field dose significantly decreases the dose OARs received, and it is meaningful that more locally advanced patients can receive concurrent chemoradiotherapy. This study will facilitate the individualized multidisciplinary treatment of patients with LANSCLC, which needs further prospective studies to confirm.

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      P2.01-90 - Dosimetry Prediction of Locally Advanced Non-Small Cell Lung Cancer Based on the Tumor Location and the Volume Ratio of Tumor to Lung (ID 2052)

      10:15 - 18:15  |  Author(s): Yaping Xu

      • Abstract

      Background

      Based on the tumor location and the volume ratio of tumor to lung, we give a method to predict the lowest dose-volume histogram (DVH) curve for the locally advanced non-small cell lung cancer patients.

      Method

      Fifty locally advanced non-small cell lung cancer patients were randomly chosen from Shanghai Pulmonary Hospital, who were treated with radical radiotherapy by intensity modulated radiotherapy(IMRT) technique. The volume of the PTV for these 50 patients range from 44.65cc to 935.36cc, and they were located in different position of the lung. All of the patients received 60Gy total dose in 30 fractions, and at least 95% of the PTV were covered by the prescription dose. All the treatment plans were required to have their optimal results based on the lowest DVH curve of the lung, and the final DVH of the lung were analyzed according to the tumor location and its volume ratio relative to the lung.

      Result

      By analyzing the tumor location in lung and the volume ratio of tumor to lung, it is found that the DVH for the lung cancer can be predicted. When the tumors are in the same position, as the volume ratio of tumor to lung increases, the dose volume of the lung will increase proportionally; when the tumors are located in different positions, even if the volume ratio of tumor to lung is the same, the DVH of the lung appears differently; and moreover, it is found that the volume of the lung affects the DVH of the lung much more than the volume ratio of tumor to lung, ie, even though the volume ratio of tumor to lung has a larger value, if the lung has a larger volume, a lower DVH curve of the lung can be obtained. At last, we found that, in any case, if the volume between the 10Gy and 65Gy is in an inverse proportional relationship and the dose received by the other OAR(organ-at-risk) is inside its safe range, then the treatment plan for the patient will be the best. The inflection point (around 6~7 Gy) of the DVH curve for the lung will be obtained, which is the extreme value of the DVH curve.

      Conclusion

      By analyzing these 50 patients’ treatment plans, the DVH of lung can be predicted for any locally advanced non-small cell lung cancer patient based on the tumor location and the volume ratio of tumor to lung. The lowest DVH curve of the lung can be assessed by its obtained inflection point.