MRI指导骨髓保护IMRT对直肠癌同期放化疗血液不良反应影响

摘要

目的：通过 IMRT 降低直肠癌患者放疗区域造血活性骨髓的受照射剂量，以其减轻在同期放化疗期间的急性血液不良反应。方法前瞻性入组直肠癌初治患者，根据盆腔核磁图像确定造血活性骨髓分布并勾画，并对其进行剂量限定（V5＜95％，V10＜90％，V20＜80％，V30＜65％），新辅助治疗方案为 IMRT 同期化疗（95％PTV50 Gy 分25次，2 Gy／次），同期每周奥沙利铂50 mg／m 2，卡培他滨每天16502（放疗期间每天2次）。结果共35例Ⅱ、Ⅲ期患者完成入组和治疗方案。2—4级血液学不良反应发生率为31％，其中白细胞减少发生率为26％（9例）、中性粒细胞减少发生率为17％（6例）、红细胞减少发生率为3％（1例）、血小板减少发生率为3％（1例）。多元 Logistic 线性回归分析表明造血活性骨髓 V5与白细胞、中性粒细胞和血小板最低值均显著相关（P＝0.005、0.002、0.017）。结论根据 MR 确定的骨盆造血活性骨髓受量与直肠癌患者新辅助同期放化疗急性血液不良反应发生率和严重程度明显相关。临床试验注册ClinicalTrials．gov，注册号：NCT01863420。%Objective To reduce the radiation dose to the hematopoietic bone marrow (hBM) and acute hematologic toxicity (HT) in patients with rectal cancer undergoing intensity-modulated radiotherapy (IMRT).Methods The previously untreated patients with rectal cancer were enrolled in a prospective study.Pelvic magnetic resonance imaging ( MRI) was used to determine and delineate the distribution of hBM,and dose limitations were set (V5<95%,V10<90%,V20<80%,V30<65%).The neoadjuvant therapeutic regimen included concurrent IMRT (95% PTV 50 Gy/25 fractions,2 Gy/fractions),oxaliplatin 50 mg/m2 , qw,and capecitabine 1650 mg/m2 ,1 fractions/d (twice a day during radiotherapy).Results A total of 35 patients were enrolled and completed the therapeutic regimen.The incidence of grade 2-4 HT was 31.4%;among these patients, 9 ( 26%) experienced leucopenia, 6 ( 17%) experienced neutropenia, 1 ( 3%) experienced erythropenia,and 1(3%) experienced thrombocytopenia.No patients experienced grade ≥3 anemia.The multivariate logistic linear regression analysis showed that hBM-V5 was significantly correlated with the lowest counts of leukocytes ( P=0.005),neutrophils ( P=0.002),and platelets ( P=0.017).Conclusions The radiation dose to the hBM in the pelvis on MRI is significantly correlated with the incidence and severity of acute HT in patients with rectal cancer undergoing neoadjuvant concurrent chemoradiotherapy.Clinical Trial Registry ClinicalTrials.gov,registration number:NCT01863420.