A Comparative Study On The Incidence Of Lymphedema After Radiotherapy In Breast Cancer Delineated By Two Methods For Target Volume

Objective:Tocompare two methods for breast cancer target volume delineation in the axillary lymph node region irradiation dose and the occurrence of lymphedema in the upper limb after radiotherapy.Methods:Prospective cohort study method used.Breast cancer post-operation patients with radiotherapy from October 2018 to August 2019 in the department of radiation oncology,the Affiliated Hospital of North Sichuan Medical College,were collected as the study objects.They were randomly divided into 2 groups,breast cancer postoperative target volume were delineated respectively by referring to the European Society for Radiotherapy and Oncology(ESTRO)consensus guidelines and the Radiation Therapy Oncology Group(RTOG)consensus definitions,all of the axillary lymph node levels ?,? and ? were delineated as normal tissue referring to the RTOG consensus definitions.The prescription dose of 50-50.4Gy in 25-28 fractions.After the completion of the radiotherapy plan,the target volume and the axillary lymph node region irradiation dose were analyzed by using the dose-volume histogram.Regular follow-up after radiotherapy was completed to evaluate the occurrence of lymphedema in the upper limb of the study subjects.The circumferential measurement of the upper limb was for objective signs and the breast cancer lyphedema questionnaire(LBCQ)score was used for subjective symptoms.The incidence and symptom score of lymphedema were compared between the 2 groups,and the relationship between edema and the incidence of single symptom was analyzed.Results:Complete data of 127 cases were obtained finally,including 65 cases in the ESTRO group and 62 cases in the RTOG group,with an average follow-up time of 97.5 days.The volume ofP-CTV1(ipsilateral cheat wall)in the ESTRO group and RTOG group was 344.56±71.74cm3and 457.5 ±114.88cm3,respectively,and that of P-CTV2(ipsilateral supraclavicular lymph node region)was 57.5±14.89cm3 and 87.6±16.66cm3,the difference was statistically significant(P<0.001).There was no significant difference between the two groupsin the each axilly region of the mean doseandthe percentage volumes receiving different irradiation doses(V30,V35,V40,V45,V50,V55)(P>0.05).Pearson correlation analysis showed that the volume of P-CTV1 was negatively correlated with axillary level ? V30 and V35,and the volume of P-CTV1 and P-CTV2 was positively correlated with axillary level III V55.There were 21 cases of lymphedema diagnosed by measuring the circumference of the upper arm,with an incidence rate of 16.5%.The incidence rates of the ESTRO group and the RTOG group were 12.3%and 21.0%(P>0.05).The LBCQ score evaluated the ESTRO group and the RTOG group with scores of 5.55±2.82 and 4.08±3.74,respectively(P<0.05).There were 91.3%of the patients with edema related symptoms,and most of the patients had multiple symptoms.The corrected chi-square test or Fisher's accurate probability method showed that the incidence of tightness and upper limbswelling in patients with edema was higher than that in patients without edema(P<0.05).Conclusions:Two target volume delineation methods have an impact on the incidence of lymphedema after radiotherapy for breast cancer.The ESTRO consensus guidelines effectively reduce the radiotherapytarget volume,and the incidence of lymphedema showed a decreasing trend.Among the subjective symptoms of breast cancer patients,tightness and upper limb swelling can provide important information for clinical screening of lymphedema.