| Purpose:Acute myelosuppression is one of the common complications of concurrent chemoradiotherapy for rectal cancer.There are few data on the incidence of pelvic radiotherapy and acute blood toxicity（Hematologic Toxicity,HT）.Dynamic changes in the development of acute myelosuppression during pelvic radiotherapy are unclear.This study aims to explore the impact of clinical and physical factors on acute myelosuppression and attempt to find valuable indicators to predict and control the occurrence of acute hematologic toxicity.Method:A retrospective analysis of the concurrent treatment of rad iotherapy or radiotherapy in the Department of Oncology of the Third Hospital of Hebei Medical University from January 2010 to June 2017,And there are 69 cases of rectal cancer patients with complete medical records,There were 47 males and 22 females.The age range was 21 t o 87 years.The median age was 61 years and the average age was 60years;Of these,39 cases were postoperative patients（including 9 cases of postoperative recurrences）and 30 cases without surgery;All patients were diagnosed as rectal adenocarcinoma by pathology.The clinical sta ging was performed according to the eighth edition of American Joint Committee on Cancer（AJCC）staging criteria.There were 2 cases of st age I,31 cases of stage II,27 cases of stage III,and 9 cases of stage IV.KPS scores were≥70 points.Among them,40 patients received che moradiation during the same period,and 29 patients received radiotherap y alone.Before radiotherapy,all patients were evaluated for no radiothe rapy contraindications.All patients had detailed medical records,radiothe rapy plan records,and complete pelvic dose-volume data.Follow-up dat a includes blood cell count data and diagnosis and treatment.The study was informed and approved by the hospital’s ethics committee after inf ormed consent of the subjects or their families.Prior to the developmen t of the radiotherapy plan,each patient was delineated with the pelvic b one within the irradiation range（including the sacrum,the lower pelvis,and the lumbosacral vertebrae）,and the skeleton was replaced by the b one skeleton.According to different treatment methods,they were divide d into capecitabine concurrent chemoradiation（observation group）and ra diotherapy alone（control group）.The use of capecitabine was 1650 mg/m 2/day,Bid for 5 days/week until the end of radiotherapy.Both grou ps were performed three-dimensional conformal intensity modulated radia tion therapy,95%PTV,50Gy/2Gy/25f,conventional segmentation,5f/W,and the dose-volume histogram DVH was derived according to the trea tment plan,and was obtained for each patient.Bone V10-40,average d ose（Dmean）of tibiae and volume of tibia;low pelvis V10-40,average dose of low pelvis and low pelvic volume;lumbosacral vertebrae V10-40,lumbosacral The average dose of vertebral exposure and lumbosacral volume;the average dose and volume of pelvic V10-40,pelvic exposure;95%PTV dose（PTV Dose）and PTV Volume（PTV Volume）.In the DVH parameter,VX=the proportion of the volume that received X G y irradiation.This experiment uses absolute volume.Each patient’s white blood cell count（WBC）,neutrophil count（ANC）,lymphocyte count（A LC）,hemoglobin concentration（Hgb）,and platelet count（PLT）were rec orded before radiotherapy.The above counts were measured every week after radiotherapy and chemoradiation from the same period,and the bl ood cells were ranked according to the lowest one hematological toxicit y record.All patients in the acute phase of myelosuppression assessment were evaluated by the United States Radiation Oncology Cooperative O rganization（RTOG）grading standard.SPSS 21.0 statistical software was used for statistical analysis.The statistical description of the measurem ent data was expressed as mean±standard deviation（x±s）.The internal a nd intergroup comparisons in each group were based on different data t ype distributions using t-test and paired t-test respectively.Wilcoxon ran k sum test;count data using chi-square test or Fisher’s exact probability method,statistical analysis of relevant clinical factors;normal distributi on of two-sample means using t test,non-normal dose data using two i ndependent samples Non-parametric test;multivariate analysis of selected clinical factors and dosimetric factors using logistic regression analysis,screening of independent statistically significant influencing factors,sign ificance test level P<0.05;application subject working characteristic curv e（receive operating characteristic curve,ROC）evaluates dosimetric facto rs associated with acute myelosuppression and predicts bone marrow dos imetry margins for acute myelosuppression.Results:1.All patients in the whole group received WBC,ANC,PLT,AL C,RBC,and Hgb at different time intervals during radiotherapy.There was a statistically significant decrease in hematocrit and baseline before radiotherapy（P=0.000）,with white blood cell count（WBC）,neutrophil c ount（ANC）,platelet count（PLT）before radiotherapy（6.662±1.501）×10 9/L、（4.069±1.402）×10 9/L、（235.568±66.572）×10 9/L dropped to the lowest values in the second week（4.136±1.256）×10 9/L respective ly.（2.662±1.092）×10 9/L、（167.059±44.910）×109/L significantly diffe rent from those before radiotherapy（P=0.000）,and gradually began to re cover.Multiple comparisons showed that the white blood cell count at t he fifth week of the patient（5.769±1.663）×10 9/L was still lower than t he baseline white blood cell count at the beginning of radiotherapy,and there was a statistically significant difference（P=0.001）.There was no significant difference in white blood cell count（WBC）,neutrophil count（ANC）,and platelet count（PLT）between the second and third week（P=0.317,0.124,0.770,respectively）.At the same time,we obtained red blood cell（RBC）,hemoglobin concentration（Hgb）,hematocrit,lymp hocyte count（ALC）values from（4.405±0.535）×1012/L,（136.833±16.558）g/L,（40.738±4.771）,（2.008±0.682）×10 9/L began to decline,the low est value occurred at the end of radiotherapy in the fifth week,respecti vely（3.621±0.569）×10 9/L,（115.874±16.804）g/L,（34.314±4.834）and（0.473±0.188）×10 9/L were significantly different from those b efore radiotherapy（P=0.000）.The same dynamic changes were observed in the concurrent radiotherapy and chemotherapy group and radiotherap y alone group.2.T test for the same period group and radiotherapy group of each cell type that the lowest value,white blood cell count in peripheral bl ood during the same period group（WBC）,neutrophil count（ANC）,plat elet count（PLT）,red blood cell（RBC）,hemoglobin concentration（Hgb）,hematocrit,lymphocyte count（ALC）respectively（4.009±0.947）×10 9/L、（2.593±0.827）×10 9/L、（161.690±43.638）×10 9/L、（3.588±0.602）×1012/L、115.365±15.989 g/L、34.095±5.001、（0.441±0.158）×109/L rad iotherapy group were lower than that of（4.309±1.590）×10 9/L、（2.758±1.388）×10 9/L、（174.466±46.344）×10 9/L、（3.667±0.529）×1012/L、116.242±17.564 g/L、34.616±4.665、（0.517±0.218）×109/L,but the difference was not statistically significant（P=0.331,0.54,0.246 0.577,0.832,0.662,0.098）.3.We obtained the Pearson correlation analysis of the entire sampl e,and the baseline of WBC values was linearly positively correlated wi th the lowest WBC value（R=0.714,P<0.05）,which was statistically sig nificant.4.Acute myelosuppression was 71.01%（49/69）in all patients,and the incidence of grade 2 acute myelosuppression was 27.5%（19/69）.Of these,13 were grade 2,6 were grade 3,and none were grade 4 or hi gher.Acute bone marrow suppression occurs.Acute myelosuppression in the concurrent radiochemotherapy group was 75%（30/40）,and the incid ence of grade 2 acute myelosuppression was 30%（12/40）,9 of which were grade 2,3 were grade 3,no grade 4 Acute myelosuppression occu rred.The incidence of acute myelosuppression was 65.52%（17/29）in th e pure radiotherapy group,and 24.14%（7/29）of the grade 2 acute mye losuppression occurred.Of these,4 were grade 2 and 3 were grade 3.No≥4 grade of acute bone marrow suppression occurred.5.There was no correlation between gender,age,clinical stage,ope ration status,whether or not chemoradiotherapy and other clinical factors were greater than or equal to grade 2 HT（P>0.05）,gender,clinical st age,surgical status,whether to perform concurrent radiotherapy and che motherapy,and≥2 There was no correlation between graded leukopenia（P>0.05）and age-related risk factors for leukopenia of grade≥2（P=0.02）.6.Non-parametric test results showed that the sacrum V15,V20,V25,V35,pelvic V20,V25,lumbosacral V10,V15,V20,V25,V35,and pelvic V10,V15,V20 doses were significantly higher in≥2 HT patien ts.For patients with<2 HT,there was a statistically significant differen ce（P<0.05）.Patients with≥2 grade leukocytopenia had an average dos e of tibial V20,V25,V35,V40,and iliac bone.The doses of lower pe lvis V20,V25,and pelvic V15,V20 were significantly higher than thos e with grade 2 leukopenia,and there were statistical Significance（P<0.05）.The Logistic multivariate regression analysis showed that screening o f meaningful values into the skeletal V20,low pelvic V25,lumbosacral V25 was an independent risk factor for≥2 HT,and humeral V20 was an independent risk factor for≥2 leukopenia.Using the receiver operati ng characteristic curve（ROC）,the predictive cut-off value of tibial V20for≥2 grade HT was 198.446cc,the predictive cut-off value for low p elvic V25 was 231.424cc,and the predictive cut-off value for lumbosacr al V25 was obtained.232.694cc.The predictive cut-off value of tibial V20 with≥grade 2 leukocytes was 252.482 cc.Conclusions:1.During pelvic radiotherapy,different cellular components of the p eripheral blood decrease to varying degrees.Different blood cell counts reach the lowest point in time,and the trend of change is not the same.It shows that there are differences in the radiosensitivity of different bl ood cells.2.≥2 grades of acute myelosuppression are associated with low-d ose volume parameters.Considering V20 of the sacrum,V25 of the low er pelvis,and V25 of the lumbosacral vertebrae can reduce the incidenc e of acute hematologic toxicity. |
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