ESTRO 2022 - Abstract Book

S323

Abstract book

ESTRO 2022

Figure 1. Probability of deterioration in atrophy for a patient of mean BMI and biological equivalent dose (BED) (94 Gy) for both wide local excision and segmentectomy / quadrantectomy, derived from fixed-effect logistic regression models incorporating a) rs1801260 in CLOCK, b) rs2087947 in PER3, c) rs11545787 in RASD1, d) Combined unweighted PRS score of all three SNPs. Shaded areas bounded by dashed lines show 95% confidence intervals

Mini-Oral: 10: Lung

MO-0387 Durvalumab increases the risk of radiation pneumonitis in non-small-cell lung cancer patients

R. Stoffers 1 , A.G. Niezink 1 , O. Chouvalova 1 , A.H. van der Leest 1 , J.F. Ubbels 1 , M. Woltman-van Iersel 1 , J.A. Langendijk 1 , R. Wijsman 1

1 University Medical Center Groningen, Radiation Oncology, Groningen, The Netherlands

Purpose or Objective The addition of adjuvant durvalumab to chemoradiotherapy (CRT) in locally advanced NSCLC resulted in a significant improvement of OS and PFS. Several single centre studies reported on an increase in adverse events, in particular in radiation pneumonitis (RP). However, large cohort studies presenting real-world data are lacking. The aim of this study was to investigate the incidence of RP after CRT with adjuvant durvalumab immunotherapy in patients with locally advanced NSCLC. Materials and Methods The study population was composed of all patients with NSCLC that completed CRT with curative intent between February 2013 and October 2020. From 2018 on, adjuvant durvalumab immunotherapy was administered in patients with locally advanced stage (II-III) disease, a WHO performance of 0-1 and without disease progression after completion of CRT. Patient and tumour characteristics, dosimetric RT data, chemotherapy and immunotherapy data together with RP data (CTCAE v4.0, scored up to 9 months after CRT), were prospectively collected as part of our standard follow up program. Results A total of 318 patients were enrolled, of which 97 (30.5%) received adjuvant durvalumab. Baseline patient and tumour characteristics did not differ between the two groups. Patients in the durvalumab group received proton therapy more often. A significant increase in the incidence of grade ≥ 2 RP in patients receiving durvalumab compared to CRT only was observed (17.5% vs. 8.6%; HR: 2.27, 95%CI: 1.17-4.41, p=0.016). In the first six months after ending CRT, both groups had equal cumulative RP incidences. Interestingly, after these six months, patients receiving adjuvant durvalumab developed RP more frequently compared to patients treated with only CRT (Figure 1). In multivariable logistic regression analysis, adjuvant treatment with durvalumab was significantly associated with a higher incidence of grade ≥ 2 RP (HR 2.57, 95%CI: 1.24-5.33, p=0.011). Also, the risk of RP increased with higher MLD (HR 1.16, 95%CI: 1.04-1.29, p=0.009). Treatment with