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Ming Liu,1,2 Xiaoyang Li,3 Huaidong Cheng,2 Yansu Wang,4 Ye Tian1 1Department of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Institute of Radiotherapy and Oncology, Soochow University, Suzhou, 215004, People’s Republic of China; 2Department of Oncology, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, People’s Republic of China; 3Department of Radiation Oncology, The First Affiliated Hospital of USTS, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, People’s Republic of China; 4Department of Radiation Oncology, Shanghai Tenth People’s Hospital, Shanghai, 200072, People’s Republic of ChinaCorrespondence: Ye TianDepartment of Radiotherapy and Oncology, The Second Affiliated Hospital of Soochow University, Institute of Radiotherapy and Oncology, Soochow University, Suzhou, 215004, People’s Republic of ChinaTel +86-512-67783430Fax +86-512-68284303Email dryetian@126.comPurpose: The objectives of the present study are to perform a survival analysis of patients with thoracic esophageal squamous cell carcinoma (ESCC) receiving definitive radiotherapy and to identify prognostic factors from among the hematological and dosimetric factors.Methods: Cases of thoracic ESCC treated with radical RT between 2014 and 2017 were identified. The impact of clinicopathological factors on overall survival (OS) were analyzed using the Cox proportional hazards model. Absolute lymphocyte counts (ALC) and the neutrophil-to-lymphocyte ratio (NLR = ANC/ALC) were assessed before, during, and after radiotherapy (RT). Cox regression was used to correlate clinical factors with hematologic toxicities, dosimetric parameters and overall survival. Multiple logistic regression analysis was used to identify associations between lymphopenia and dosimetric parameters. With the overall survival status and real time events, the X-tile program was utilized to determine the optimal cut-off value of pretreatment NLR, and ALC nadir.Results: Ninety-nine ESCC patients were enrolled in the present study. They had a median OS of 23 months. The median RT dose was 55.75Gy (46– 66Gy), and the mean dose (Dmean) of the thoracic vertebrae (TVB) was 27.04± 9.65Gy. Based on the multivariate analysis, the V20 of TVB, the pretreatment NLR, and the ALC nadir were associated with significantly worse OS. Concurrent CRT, which entailed increasing the mean TVB dose and V20 of TVB, was linked to a higher probability of lymphopenia risk (P< 0.05). This was ascertained through the multiple logistic regression analysis.Conclusion: In ESCC patients who received definitive RT, V20 of TVB, pretreatment NLR, and ALC nadir during RT were independent prognostic factors and chemotherapy regimen, mean TVB dose, and V20 of TVB were associated with lymphopenia.Keywords: radiotherapy, lymphopenia, esophageal cancer, dosimetric parameters, overall survival

T Kumar,1–3 A Schernberg,1,2 F Busato,1,2 M Laurans,1,2 I Fumagalli,1,2 I Dumas,1,2 E Deutsch,1,2 C Haie-Meder,1,2 C Chargari1–2,4–51Brachytherapy Unit, Gustave Roussy, Cancer Campus, Villejuif, France; 2Radiotherapy Department, Gustave Roussy, Villejuif, France; 3Radiotherapy Department, University Hospital of Grenoble, Grenoble, France; 4Departement ’Effets Biologiques des Radiations’, Institut de Recherche Biomédicale des Armées, Brétigny sur Orge, France; 5French Military Health Academy, Ecole du Val-de-Grâce, Paris, FrancePurpose: To evaluate the association between pelvic bone marrow (BM) dose volume parameters and probability of acute hematological toxicity (HT), a cohort of cervical cancer patients receiving definitive chemoradiation (CRT) was assessed.Materials and methods: Medical records of patients treated by CRT (45 Gy in 25 fractions, without dose constraints applied to the BM) were reviewed. Baseline and weekly hematological parameters were collected. BM was retrospectively delineated and divided into sub-sites: iliac crests, lower pelvis, lumbosacral region. BM volumes (V) receiving 5, 10, 20, 30, 40 Gy (V5, V10, V20, V30, V40, respectively) and mean dose (Dm) were calculated. Logistic regression was used to analyze associations between HT and dose-volume histograms parameters.Results: 114 patients were included. 75.4% were treated with 3D radiation therapy and 24.6% were receiving intensity modulated radiation therapy (IMRT). Neither age, chemotherapy regimen (cisplatin vs carboplatin), number of chemotherapy cycles, performance status, body mass index, or para-aortic irradiation were associated with HT. In univariate analysis, more frequent grade 3+ leukopenia was found in the IMRT group (odds ratio [OR]: 3.5; 95% CI, 1.4–9.1; p=0.007). In multivariate analysis, grade 4 HT was associated with lower pelvis V5>95% (OR 4.1; 95% CI, 1.6–14. p=0.02), lower pelvis V20>45% (OR 3.5; 95% CI, 1.1–13.4; p=0.05), total pelvic bone V20>65%, and iliac crests Dm >31 Gy (OR 4.5; 95% CI, 1.4–14.7; p=0.02).Conclusion: The following dose constraints could be proposed to decrease acute HT risk: lower pelvis V5

Purpose: To investigate the potential dosimetric benefits from four-dimensional computed tomography (4DCT) compared with three-dimensional computed tomography (3DCT) in radiotherapy treatment planning for external-beam partial breast irradiation (EB-PBI)., Patients and Methods: 3DCT and 4DCT scan sets were acquired for 20 patients who underwent EB-PBI. The volume of the tumor bed (TB) was determined based on seroma or surgical clips on 3DCT images (defined as TB3D) and the end inhalation (EI) and end exhalation (EE) phases of 4DCT images (defined as TBEI and TBEE, respectively). The clinical target volume (CTV) consisted of the TB plus a 1.0 cm margin. The planning target volume (PTV) was the CTV plus 0.5 cm (defined as PTV3D, PTVEI, and PTVEE). For each patient, a conventional 3D conformal plan (3D-CRT) was generated (defined as EB-PBI3D, EB-PBIEI, and EB-PBIEE)., Results: The PTV3D, PTVEI, and PTVEE were similar (P=0.549), but the PTV coverage of EB-PBI3D was significantly less than that of EB-PBIEI or EB-PBIEE (P=0.001 and P=0.025, respectively). There were no significant differences in the homogeneity or conformity indexes between the three treatment plans (P=0.125 and P=0.536, respectively). The EB-PBI3D plan resulted in the largest organs at risk dose., Conclusion: There was a significant benefit for patients when using 3D-CRT based on 4DCT for EB-PBI with regard to reducing nontarget organ exposure. Respiratory motion did not affect the dosimetric distribution during free breathing, but might result in poor dose coverage when the PTV is determined using 3DCT.