ESTRO 2024 - Abstract Book

S2177

Clinical - Upper GI

ESTRO 2024

Results:

Among 1,337 included patients, 68% received photon-based and 32% received proton-based CRT. Median follow-up duration for the whole group was 24.9 months. In univariable analysis, significant predictors of survival included age, body mass index (BMI), sex, WHO performance status, diabetes, smoking status, tumor location, histology, and clinical TNM-stage. In multivariable analysis (adjusted for the clinical predictors), the best performing model was with the ALC in week 3 of CRT, with a corrected time-dependent c-statistic of 0.683 for PFS and of 0.662 for OS, compared to 0.677 for PFS and 0.657 for OS for lymphopenia grade 4. The models for ALC in week 3 and lymphopenia grade 4 are shown in Table 1. The optimal threshold that maximized the survival difference was determined at an ALC in week 3 of <0.5 x103/μL which corresponds to grade ≥3 lymphopenia according to CTCAE. As such, grade ≥3 lymphopenia in week 3 of CRT was independently and significantly associated with PFS (adjusted hazard ratio [aHR] 1.64; 95% confidence interval [CI] 1.27-2.13) and OS (aHR 1.56; 95%CI 1.15-2.08, respectively). In 716 patients with an ALC in week 3 of <0.5 x103/μL the 5 -year PFS and OS were 29% and 38%, respectively, (i.e. grade ≥3 lymphopenia), versus 40% and 51%, respectively, in 621 patients with ALC in week 3 of ≥0.5 x103/μL (Figure 1). For patients with lymphopenia grade 4 during CRT, the 5-year PFS and OS was 28% and 36%, versus 37% and 49% for patients without lymphopenia grade 4, respectively.