ESTRO 2020 Abstract book

S908 ESTRO 2020

(G1-4) and increase of cough during RT were related to RP≥G2 (p=0.044, p=0.008, Figure 2), while cough at baseline and increase of dyspnea during RT were not significant. Risk factors for RP were significant for infection at baseline or during RT (OR=8.087, p=0.026), GTV size (OR=1.077/10cm3, p=0.002) and PTV size (OR=1.264/100cm3, p=0.004). Smoking (OR=0.160, p=0.063) and MLD (OR=1.077/Gy, p=0.067) did not reach significance. None of the recorded pulmonary function measures were linked to RP. In the multivariate logistic regression analysis, the null model (equaling the general probability of RP≥G2 in the cohort) was within one standard deviation of the minimum deviance.

PO-1581 Prospectively scored pulmonary toxicities from a non-small cell lung cancer dose escalation trail C.M. Lutz 1 , M.M. Knap 2 , L. Hoffmann 2 , D.S. Moeller 2 , O. Hansen 3 , C. Brink 4 , T. Schytte 3 , C. Nyhus 5 , T. McCulloch 6 , S. Borissova 7 , M. Alber 8 , A. Khalil 2 1 Aarhus University Hospital, Department of Oncology, Aarhus C, Denmark ; 2 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark ; 3 Odense University Hospital, Department of Oncology, Odense, Denmark ; 4 Aarhus University Hospital, Department of Oncology, Odense, Denmark ; 5 Vejle Hospital, Department of Oncology, Vejle, Denmark ; 6 Aalborg Hospital, Department of Oncology, Aalborg, Denmark ; 7 Herlev University Hospital, Department of Oncology, Herlev, Denmark ; 8 Heidelberg University Hospital, Heidelberg Institute for Radiation Oncology, Heidelberg, Germany Purpose or Objective Local control and overall survival are poor in locally- advanced non-small cell lung cancer (LA-NSCLC). Unfortunately, intensified radiotherapy (RT) is limited by a high risk of pulmonary toxicities. This study investigated the prospectively scored pulmonary toxicities observed in a multicenter randomized phase II trial (NARLAL). Material and Methods Patients with stage IIB-IIIB histologically proven LA-NSCLC were recruited May 2009-August 2013 at five Danish RT centers. A total of 117 patients were treated with concomitant chemo-RT at 60Gy/30fx (arm A–59pts) and 66Gy/33fx (arm B–58pts). Pulmonary function tests (FEV1, FVC) were recorded. Pulmonary toxicities were reported as radiation pneumonitis (RP), dyspnea and cough (CTCAE v3.0). RP was reported when observed, while dyspnea and cough were frequently scored before, during and after RT. Toxicities in arm A and B were compared with Mann Whitney U tests and a log rank test in a time to event analysis of RP≥G2. The relationship of clinical and dosimetric parameters with RP≥Grade2 was investigated with Chi2 (binary variables) and Mann Whitney U tests. For RP≥G2, a multivariate logistic regression with regularization and a 10-fold cross-validation (Least Absolute Shrinkage and Selection Operator (LASSO) function for general linear models) was used to avoid overfitting. Results RP, dyspnea and cough were not significantly different (p- values ranged 0.348 (RP) to 0.982 (Cough pre RT)) between the two arms. Mean lung dose did not reach significance (MLD_A=14.9Gy [5.8,23.1], MLD_B=17.5Gy [8.6,24.8], p=0.075). A time to event analysis of RP≥G2 (Figure 1) indicated a tendency towards higher risk of RP in arm B but was not significant (p=0.180). The patients were henceforth analyzed as one group. Dyspnea at baseline

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