S1116
Clinical – Upper GI
ESTRO 2026
Digital Poster 4439
Impact of the Effective Dose to Circulating Immune Cells on Overall Survival and Lymphocyte Nadir in Thoracic Esophageal Cancer Nursena Çiflik, Gün Günalp, Hazan Özyurt Bayraktar, Ay ş e Sevgi Özden Radiation Oncology, Kartal Dr.Lütfi Kırdar City Hospital, istanbul, Turkey Purpose/Objective: This study aimed to investigate the relationship between the Effective Dose to Circulating Immune Cells (EDIC) and overall survival (OS) in patients with nonmetastatic thoracic esophageal cancer treated with radiotherapy, and to evaluate the correlation between EDIC and lymphocyte nadir levels. Material/Methods: Ninety-two patients (46 males, 46 females; mean age, 60 years) were retrospectively analyzed. Tumors were located in the upper, middle, and lower thoracic esophagus in 7.6%, 47.8%, and 44.6% of cases, respectively. EDIC was calculated using a previously described mathematical model incorporating mean lung, heart, and thoracic body doses. Correlations were analyzed using Spearman’s test, and survival outcomes were assessed using Kaplan–Meier and Cox regression analyses. Results: The mean EDIC was 5.43 ± 1.12 Gy. A weak, negative, and statistically non-significant correlation was observed between EDIC and lymphocyte nadir ( ρ = – 0.084, p = 0.426). Kaplan–Meier analysis showed no significant OS difference between the EDIC < 5.5 Gy and ≥ 5.5 Gy groups (p = 0.396). The 3-year overall survival rate was 54.9% in the EDIC < 5.5 Gy group and 70.1% in the ≥ 5.5 Gy group. In the Cox analysis, EDIC was not identified as an independent prognostic factor (HR = 1.045; 95% CI: 0.67–1.63; p = 0.843). Lymphocyte nadir also had no significant impact on OS (HR = 0.969; 95% CI: 0.56–1.67; p = 0.911).
Conclusion: High baseline CAC is strongly associated with cardiovascular events after radiotherapy in EC patients, especially among those receiving chemotherapy. CAC assessment can help identify high- risk patients and guide cardioprotective strategies. References: [1] Blaha MJ, et al. Coronary Artery Calcium Scoring: Is It Time for a Change in Methodology? JACC Cardiovasc Imaging. 2017;10(8):923–37. [2] Hecht HS, et al. CAC- DRS: Coronary Artery Calcium Data and Reporting System. An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT). J Cardiovasc Comput Tomogr. 2018;12(3):185–91 Keywords: Coronary artery calcification
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