Objective To identify the dose-volumetric parameters associated with acute bone marrow suppression in concurrent chemoradiotherapy for cervical cancer,and provide the reference standard for the radiotherapy planning.Methods In total,155 patients concurrently receiving chemoradiotherapy for cervical cancer were enrolled in this study.The pelvis was contoured for each patient in radiotherapy treatment planning system and divided into three subsites:lumbosacral spine,ilium,and lower pelvis.The pelvic dose volume parameters were analyzed using univariate analysis (Chi-Square and t test),and multivariate analysis (Logistic regression model).Dose volume parameters include V5,V10,V15,V20,V25,V30,V35,V40,V45,V50 and the average dose (D).Results The percentage of patients that developed acute bone marrow suppression (≥ grade 2) was 87.7％ (136/155).The univariate analysis revealed that pelvic V5,V10,V15,V,0,ilium V15,lower pelvis V15 of patients with acute bone marrow suppression (≥ grade 2) were significantly higher than those of ＜ grade 2 patients (t =-2.277,-2.142,-3.475,-2.018,-2.963,-2.741,P ＜0.05).Multiple regression analysis indicated that pelvic V15 was associated with acute bone marrow suppression (OR =1.728.P ＜ 0.05).The threshold of pelvic V15 was 88％ as determined by receiver operating curve (ROC).Conclusions The results show that Pelvic V15 is associated with acute bone marrow suppression in concurrent chemoradiotherapy for cervical cancer and is thus an independent risk factor.To better predict and control acute bone marrow suppression,pelvic V15 should be carefully controlled below 88％ in treatment planning to reduce the incidence of acute bone marrow suppression.

Objective:To analyze the clinical and physical tactors associated with acute bone marrow suppression in concurrent chemo-radiotherapy for rectal cancer and to provide a reference standard for the best clinical treatment plan. Methods:Retrospective analy-sis was performed on 62 patients with rectal cancer who received concurrent radiotherapy and chemotherapy in our department. The pelvis was contoured for each patient in the radiotherapy treatment planning system and divided into three subsites: lumbosacral spine, ilium, and lower pelvis. Prognostic clinical and physical factors were analyzed by univariate and multivariate analyses. Evaluated prognostic clinical factors included sex, age, clinical stage, original hemoglobin levels, and chemotherapy, operation, and radiation modes;physical factors included V5, V10, V15, V20, V25, V30, V35, V40, V45, V50, Dmax, and Dmean of lumbosacral spine, ilium, low-er pelvis, and pelvis. Results:The percentage of patients who developed acute bone marrow suppression (≥2 grade) was 61.3%(38/62).Univariate analysis of related factors revealed statistically significant differences were sex, chemotherapy, lumbosacral spine V45, il-ium V20, and ilium V30. Multivariate logistic regression analysis indicated that chemotherapy and ilium V30 are the risk factors for acute bone marrow suppression. The receiver operating curve showed that the threshold of ilium V30 was 44%. Conclusion:Acute bone marrow suppression is influenced by more than one factor;local control rate of the tumor and acute bone marrow suppression are tradeoffs in rectal cancer treatment. An appropriate chemotherapy method should be selected, and ilium V30 must be maintained below 44%to prevent bone marrow suppression in rectal cancer patients.