ESTRO 2020 Abstract book

S341 ESTRO 2020

Data for NF located in pelvic, inguinal en para-aortic (PAO) regions and separately PAO failure (NF PAO ) were collected from the international multicentre EMBRACE study cohort (www.embracestudy.dk). Analysis was done on data from a 2017 extraction, building on previously published work * . Missing data was handled using multiple imputation. Univariable and subsequently multivariable Cox-regression were performed using clinical variables potentially associated with NF: FIGO-stage (alternated with parameteria involvement), tumour width, uterine corpus involvement, Hb(including-nadir), overall treatment time (≥49 vs. <49 days), PAO-elective radiotherapy, local recurrence and nodal risk groups at diagnosis (pelvic without common iliac, any common iliac without PAO, any PAO nodes). Candidate multivariable models were compared with Akaike’s information criterion (AIC) to assess the model with the best fit. Subgroup analyses were performed for both NF and NF PAO in patients with the following sites of nodal involvement at diagnosis (excluding PAO-positive cases): 1. internal/external iliac, common iliac and parametrial sites, 2. any common iliac. * Nomden et al. Radiotherapy and Oncology (2019) 134: 185-190. Results 1338 patients with 152 NF and 104 NF PAO were available for analysis. For NF, the final model showed that at diagnosis larger tumour width, nodal risk groups and local recurrence after treatment were associated with a significantly higher risk of NF. With increasing Hb-nadir during treatment, however, the risk on NF was less (table 1). For NF PAO the same factors were found, with the addition that elective PAO irradiation independently lowered the risk of NF PAO (table 2). For subgroup 1 “any common iliac nodes without PAO” (HR=1.67, 95%-CI 1.00- 2.78; p=0.05) and local recurrence (HR=7.31, 95%-CI 4.20- 12.73; p<0.0001) remained significant for NF. For NF PAO virtually the same relation was seen, with the addition that PAO elective radiotherapy had a protective effect for NF PAO (HR 0.38, 95%-CI 0.17-0.86; p=0.02). For subgroup 2 only local recurrence was significant for NF.