ESTRO 2020 Abstract Book

S664 ESTRO 2020

followed by palliative radiotherapy in our center and to indentify predictors related to this parameter. As a secondary endpoint, we wanted to estimate overall survival at three months (3mOS). Material and Methods We conducted a retrospective cohort study including patients treated with palliative intent in our center from January to December 2018. Data related to clinical features and radiotherapy treatment were collected and used to compare two groups defined by their condition at the cut-off of 30 days: dead or alive. Chi-square test and logistic regression model were used to assess the impact of the studied variables on 30DM. Kaplan-Meier and log- rank test were used for a survival analysis at 3 months. 30DM and 3mOS were calculated from the beginning of the treatment to the last follow-up. Results Out of 1287 treatments, 593 were of palliative intent to 394 eligible patients with a median follow-up of 4 months. 30DM rate was 15% (59 patients) with a median time to death of 18 days (range 4-30). Characteristics of the sample according to 30DM are shown in table 1. 30-day survivors were treated with a higher number of fractions and showed a higher rate of responses to treatment. Clinical features as male sex (odds ratio [OR], 3.29, 95%CI: 1.68-6.43; p<0.001), ECOG 2-3 (Eastern Cooperative Oncology Group) (OR 4.35, 95%CI 2.39-7.92; p<0.001), KPS<70% (Karnofksy Performance Status) (OR 4.06, 95%CI 2.16-7.59, p<0.001) were significantly related to 30DM in the univariate analysis. Primary site was related to 30DM in the comparative analysis (Table 1), but only gastrointestinal (OR 5.16, 95%CI 1.36-19.60, p=0.016), lung (OR 5.483, 95%CI 1.36-18.88), prostate (OR 4.033, 95%CI 1.01-16.09, p=0.048) and melanoma (OR 12.4, 95%CI 1.966-78.196, p=0.007) were predictors of 30DM. Male sex, ECOG, Karnofsky and the presence of visceral disease were identified as an independent factor related to 30DM in the multivariate analysis. 3mOS was 43.7%. Survival curves according to sex, ECOG and the most prevalent primary tumors are shown in figure 1.

Conclusion Our results are aligned to previous studies. Male sex, ECOG, Karnofsky and presence of visceral disease were identified as an independent predictor to 30-DM for patients treated with palliative radiotherapy. This data suggests that palliative radiotherapy should be chosen reflecting about the patient’s life expectancy. Our study provides more evidence of the 30DM rate in palliative radiotherapy that may help for selecting patients that could benefit. PO-1261 Radiation pneumonitis after palliative radiotherapy in patients with interstitial lung disease M. Okumura 1 , H. Hojo 1 , N. Nakamura 1 , S. Zenda 1 , A. Motegi 1 , M. Nakamura 1 , Y. Hirano 1 , S. Kageyama 1 , V.P. Raturi 1 , T. Akimoto 1 1 National Cancer Center Hospital East, Radiation Oncology, Kashiwa, Japan Purpose or Objective Many studies have reported a risk of radiation pneumonitis (RP) after definitive thoracic radiotherapy (RT) in patients with interstitial lung disease (ILD). However, the RP risk after palliative radiotherapy in patients with ILD has not been clarified. The aim of this study was to investigate the incidence, severity, and predictive factors of RP after palliative RT in patients with ILD. Material and Methods The medical records of 59 consecutive patients with ILD who received palliative RT involving the lung field at the National Cancer Center Hospital East in Japan between April 2009 and July 2019 were retrospectively reviewed.