3575 - Effect of Prophylactic Thrombopoietin and Magnetic Resonance Guided Bone Marrow-Sparing Concurrent Chemoradiotherapy on Thrombocytopenia for Thoracic Esophageal Cancer: Final Analysis of a Phase II Study
Presenter(s)
Y. Yuan1, S. Luo2, T. Zhang1, L. Deng1, W. Liu Jr1, W. Q. Wang1, X. Wang1, J. LV1, Z. Zhou1, F. Qinfu1, Z. Xiao1, N. Bi3, and J. Wang1; 1Cancer Hospital Chinese Academy of Medical Sciences, Beijing, China, 2Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 3State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
Purpose/Objective(s): To reduce acute thrombocytopenia in patients in thoracic esophageal cancer patients treated with concurrent chemoradiotherapy (CRT) by sparing the hematopoietical active bone marrow (BM) identified by magnetic resonance (MR) and prophylactic recombinant human thrombopoietin (rhTPO).
Materials/Methods: Thoracic esophageal cancer patients staged I-IVa (AJCC 7th) were prospectively enrolled. The MR images of thoracic vertebra were fused with the simulating CT images. Active BM identified by MR was contoured as an organ at risk in the treatment plan. The treatment regimen consisted of BM-sparing intensity modulated radiotherapy (BMS-IMRT) (=45Gy) and concurrent chemotherapy (five cycles of weekly intravenous paclitaxel [50 mg/m²] and cisplatin/nedaplatin [25 mg/m²], or two cycles of intravenous paclitaxel [135-175 mg/m²] and cisplatin [80 mg/m²]), and rhTPO (15000U ih. qw during the radiotherapy). The dose limits for active BM are: volume received more than 5 Gy (V5)<95%,V10<85%,V20<60%,V30<40%. The primary endpoint is any grade of thrombocytopenia during the radiotherapy and 1 month after the radiotherapy. In order to lower the incidence of thrombocytopenia from 40% to = 15% by BMS-IMRT plus prophylactic rhTPO, 23 patients are needed with 80% power to declare 25% absolute reduction compared with that of historical report at a 1-sided significance level of 0.05.
Results: From July 20 2023 to June 30 2024, a total of 32 patients met the inclusion criteria for this study. One patient failed to finish MR, three patients had grade 1(G1) thrombocytopenia and one patient had disease progressed during screening phase. Finally, 27 patients were enrolled. Our patient population was predominantly male (92.6% men vs. 7.4% women), with a median age of 59 years (range, 38–75 years). A majority of patients presented with stage II-IVa (70.4%). Before concurrent CRT, seven patients received inductive chemotherapy combined with or without immunotherapy. All patients finished the treatment plan with median radiation dose of 49.45Gy (range 42.8 - 66.66Gy). Concurrent chemotherapy was administered with a median cycle of 5 cycles (range 1-5 cycles). Four patients (14.8%) developed thrombocytopenia (1 pts with G1 and 3 pts with G3). 11 patients experienced leukopenia (2 pts with G1, 7 pts with G2 and 2 pts with G3). Only one patient happened anemia (G2).
Conclusion: Techniques to limit low dose radiation to active BM and prophylactic rhTPO could reduce thrombocytopenia in thoracic esophageal cancer patients treated with CRT. (registered in Clinical Trials.gov as NCT05944809)