en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: We aimed to investigate the relationship between the radiation dose received by the spleen and the hematological parameters of patients who underwent chemoradiotherapy after the diagnosis of locally advanced pancreatic cancer (LAPC).Materials and Methods: Patients with LAPC who were treated with chemoradiotherapy were retrospectively reviewed. Surgical status,chemoradiotherapy details, complete blood count values (baseline, mid-treatment, and end-of-treatment), mean spleen dose, and dose-volume parameters (V5, V10, V15, V20, V25, and V30) were recorded. The relationship between spleen dose-volume parameters and the development of grade 3 lymphopenia was evaluated by Spearman&#39;s rank correlation and receiver operating characteristic (ROC) analysis. Results: All dose parameters for the spleen were significantly correlated with the mid-treatment absolute lymphocyte count. In the ROC analysis, mean spleen dose (p=0.011; area under the curve [AUC]: 0.856; 95% confidence interval [CI]: 0.675-0.995), V15 (p=0.020; AUC: 0.938; 95% CI: 0.830-0.997), and V20 (p=0.002; AUC: 0.940; 95% CI: 0.811-0.1000) were significantly associated with mid-treatment grade &ge;3 lymphopenia. Conclusion: A significant correlation was found between the dose received by the spleen during chemoradiotherapy in LAPC patients and the development of lymphopenia. Contouring the spleen as an organ at risk (OAR) and documenting doses is important to establish dose limitations.</div> Pancreatic cancer, lymphope-nia, spleen radiation dose, acute toxicity. 421 425 http://ijrr.com/browse.php?a_code=A-10-1-1061&slc_lang=en&sid=1 G.A. Inan goncaaltinisikinan@gmail.com 7900319475328460024139 7900319475328460024139 Yes Department of Radiation Oncology, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey I.P. Aral 7900319475328460024140 7900319475328460024140 No Department of Radiation Oncology, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey H.F. Ozturk 7900319475328460024141 7900319475328460024141 No Department of Radiation Oncology, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey Z. Gani 7900319475328460024142 7900319475328460024142 No Ankara City Hospital, Department of Radiation Oncology, Ankara, Turkey S.A. Arslan 7900319475328460024143 7900319475328460024143 No Department of Radiation Oncology, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey Y. Tezcan 7900319475328460024144 7900319475328460024144 No Department of Radiation Oncology, Faculty of Medicine, Ankara Yıldırım Beyazıt University, Ankara, Turkey