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Sevilay Erdem



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    P2.01 - Advanced NSCLC (ID 159)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Advanced NSCLC
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.01-47 - Ipsilateral Lung Dose Constraints Predict Radiation Pneumonitis Better Than Conventional Ones in NSCLC Patients Treated with RCT (Now Available) (ID 337)

      10:15 - 18:15  |  Author(s): Sevilay Erdem

      • Abstract
      • Slides

      Background

      Mean lung dose (MLD) and percent of total lung volume that receive a dose greater than 20 Gy (V20) have been mostly validated parameters in prediction of radiation pneumonitis (RP). But these parameters present mean values of total lung parenchyme and predict the right and the left lung as a unique functional organ unit, not take into account the difference in function, dose density and radiosensitivity between the lungs. Also, there has been very limited data evaluating ipsilateral lung dosimetric constraints in addition to total lung parameters to predict RP in NSCLC-patients treated with radiochemotherapy (RCT).

      Method

      Between 2010-2017, clinical-radiological findings of NSCLC-patients treated with RCT were evaluated in terms of RP, retrospectively. The right and the left lung were contoured separately.The total lung was created by extracting PTV. Ipsilateral lung was described as the lung containing more than 50% of PTV and was created by extracting PTV from ipsilateral lung.

      Pulmonary toxicity was graded according to RTOG/EORTC.Clinicaly important RP was defined as ≥ grade 2 lung morbidity.

      The primary end point was to asses the relation between ipsilateral lung dose constraints and RP risk.The secondary end-point was to evaluate the predictive value of ipsilateral dose constraints in case of a relationship.

      Result

      There were 75 patients.There was ≥ grade 2 RP in 33 cases (%44).Median age at diagnosis was 59.The median follow-up was 21 months.The median RT dose was 63 Gy.There was ≥ grade 2 RP in 33 cases(%44).RP risk was 75% if the tumor was located in upper lobe(p:0.012).

      Univariate analysis was carried on clinical and dosimetric variables.The most significant ones were;ipsilateral MLD(p<0.001), ipsilateral V20(p<0.001), ipsilateral V30(p<0.001) and total lung V30(p<0.001).

      Ipsilateral MLDp<0.001(OR:1.34)(%95CI:1.16-1.55) and PTV p:0.039(OR:1.002)(%95CI:1.000-1.004) were found to be the independent risk factors for RP.

      The diagram of ROC curve analysis is shown in Figure 1.AUC values for ipsilateral MLD, ipsilateralV20, ipsilateralV30, MLD, V20 and V30 were 0.84, 0.80, 0.81, 0.64, 0.69 and 0.77, respectively.Threshold values for ipsilateral MLD, ipsilateral V20 and ipsilateral V30 were selected by ROC curve analysis and was determined as 18 Gy. 35% and 28% respectively.

      roc.jpg

      Conclusion

      In NSCLC-patients treated with CRT, MLD, V20 and V30 values of ipsilateral lung parameters might increase the predictablity of RP risk in addition to total lung parameters or even better. RT plannings might be improved by simply adding ipsilateral dose volume constraints witthout any additional test or effort to the patient

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