Effect of MRI-guided intensity-modulated radiotherapy with bone marrow protection on hematologic toxicity in patients with rectal cancer undergoing concurrent chemoradiotherapy / 中华放射肿瘤学杂志

ABSTRACT

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 numberNCT01863420.