ESTRO 2022 - Abstract Book

S1000

Abstract book

ESTRO 2022

Conclusion Our reported cohort shows that most male breast cancer patients present with advanced stages, and most are node-positive with a high incidence of ER-positive disease and LVSI. Even with a relatively high incidence of bone metastasis, good five- year DFS, and OS are expected.

PO-1179 The impact of PM2.5 on the radiation-induced pneumonitis in patients with breast cancer

D. KIM 1 , I.A. Kim 2 , B. Jang 2

1 Seoul National University Hospital , Radiation Oncology , Seoul, Korea Republic of; 2 Seoul National University Bundang Hospital , Radiation Oncology , Seongnam, Korea Republic of Purpose or Objective Exposure to particulate matter (PM) air pollution has been associated with adverse effect on respiratory disease, but no study has investigated its impact on radiation-induced pneumonitis (RIP) in patients with breast cancer who received adjuvant radiation therapy (RT). Materials and Methods We conducted a retrospective review of 2,762 breast cancer patients who received postoperative RT between 2017 and 2020 in a single institution. Particulate matter data including PM 2.5 and PM 10 were retrieved from the open dataset in the ‘Gyeonggi Data Dream’. We used the average, median and maximum values of the PM 2.5 and PM 10 measured during daytime when a patient visited to the hospital for RT. We excluded the patients when missing PM data exceeded 50% of the total treatment period (N=26). Finally, altogether 2,736 patients were analyzed. Results Overall incidence rate of RIP was 1.74%. There were no significant differences in average value of PM 2.5 and number of RT fractions between RIP (+) and RIP (-) groups, but marginal differences were found in RT techniques (3-dimentional conformal RT vs. intensity modulated RT, P =0.053) and proportion of PM 2.5 value ≥ 35 (µg/m3) ( P =0.053) between the two groups. After adjusting for age, RT technique, regional irradiation, fractionation and boost, the average value of PM 2.5 was significantly associated with a higher risk of RIP (Odds ratio [OR] 1.05, 95% confidential incidence [CI] 1.00-1.10, P =0.047) when patients received ≥ 20 fractions of RT. Especially, PM 2.5 ≥ 35 (µg/m 3 ) showed significant higher risk of RIP (OR 4.32, 95% CI 1.34-13.87, P =0.014) in patients with ≥ 20 fractions of RT after adjustment of aforementioned covariates. Other PM data (median, maximum value of PM 2.5 and all PM 10 values) were not related to the RIP regardless of the number of RT fractions. Conclusion This study is the first study to reveal the association between PM 2.5 and RIP in breast cancer patients who received 20 fractions or more of postoperative RT.

PO-1180 Incidental vs elective irradiation of internal mammary chain

L. Cardoso 1 , M.L. Del Valle 1 , L. Gómez 1 , S. Pena 2 , Á. Sanz 3 , M.I. Garavís 1 , M. Herrera 1 , J.F. Gutiérrez 1 , P. Valencia 1 , A. Casado 1 , R. Jaraíz 1 , E. Hurtado 2 , P. Alonso 1 , D. Rodríguez 1 , M. Sánchez 1 , I. Solís 1 , P. Diezhandino 1 1 Hospital Clínico Universitario de Valladolid, Radiation Oncology, Valladolid, Spain; 2 Hospital Clínico Universitario de Valladolid, Medical Physics, Valladolid, Spain; 3 Hospital Río Hortega , Medical Oncology, Valladolid, Spain

Purpose or Objective