Observation Of Short-term Results For Different Radiotherapy Techniques And Study Of Tumor Bed Boost Volume In Breast-conserving Surgery Patients

Objective:1. To observe the toxicities and short-term efficacy of threedifferent radiotherapy techniques after breast-conserving surgery.2. To studythe tumor bed boost volume in postoperative radiotherapy afterbreast-conserving surgery.Methods:1.Between February2007and September2011,139breastcancer patients were enrolled into this study. They all received radiationtherapy after conserving surgery at the Fourth Hospital, Hebei MedicalUniversity. All the patients met the following criteria:(1) Female;(2)T1-2N0M0in pathological stage;(3)≥70in Karnofsky Performance StatusScale;(4) Normal Liver and renal function and blood test;(5) No axillarynodes enlargement before surgery and less than positive nodes after surgery.They divided into three groups according to the way of radiotherapy. Therewere76patients receiving conventional three-dimensional Conformalradiotherapy for the whole breast (two wedged fields) and electron boost tothe tumor bed (3DCRT group),22patients receiving intensity modulatedradiotherapy for the whole breast and electron boost to the tumor bed (IMRTgroup),41patients receiving Simultaneous integrated boost intensitymodulated radiotherapy (SIB-IMRT group). All patients were positioned on acustomized supine breast board or vacuum pillow and received computedtomography (CT) simulation. The target volumes were outlined. The clinicaltarget volume (CTV) included the whole ipsilateral breast tissue without thepectoralis major,ribs and the skin in it. The former borderline was under theskin. The planning target volume (PTV) was a3D margin of0.5cm aroundCTV. A margin of1.0cm was used in the cranial and caudal directions. Thetumor bed boost volume in3DCRT group and IMRT group was2cm-3cm outside the surgical incision.5000cGy in25times was given to the wholebreast irradiation (WBI) and800-2000cGy in4-10times of7-12MeV electronwas given to the tumor bed. For the patients in SIB-IMRT group, the CTV1covered a3D margin of0.5cm around the tumor bed) and PTV1covered a3D margin of0.5cm around the breast CTV1. The organs at risk (OARs)were outlined too, such as heart, liver, lung and the contralateral breast. Totaldose were4940cGy and5980cGy was given to WBI and tumor bedrespectively in26times. The toxicities and short-term efficacy of threedifferent radiotherapy techniques after breast-conserving surgery wereevaluated.2. Thirty-one patients of139patients were included to study thetumor bed boost volume in postoperative radiotherapy after breast-conservingsurgery. There were at least3clips in their tumor bed of ipsilateral breast.During computed tomography (CT) simulation scanning, a wire equal to thelength of surgical scar on the breast was put along the scar. The surgical clipsand wires along the surgical scar were outlined in the treatment planningsystem. On the direction perpendicular to the surgical scar skin,2.0cm,2.5cmand3.0cm was expanded around the scar respectively to observe whether theexpanded tumor bed volume could cover all of clips in tumor bed.Results:(1) The median age was45years (range,23-81). Primary tumorlocated on left breast in72patients, right side66patients and bilateral breast1patient. There were107patients in stage I and32patients in stage II.(2)Theacute skin toxicities: The grade1,2and3rate were78.9%(60/76),18.4%(14/76) and2.7%(2/76) respectively in3DCRT group;86.4%(19/22),13.6(3/22)%and0respectively in IMRT group;90.2%(37/41),9.8%(4/41)and0respectively in SIB-IMRT group. No statistical difference was foundamong the three group, P=0.254. The two patients had grade3toxicity duringthe electron boost to the tumor bed after WBI.(3)Cosmesis: The good orcommon rate of breast cosmesis was64.5%(49/76),35.5%(27/76)respectively in3DCRT group;86.4%(19/22),13.6%(3/22) respectively inIMRT group;78.0%(32/41),22.0%(9/41) respectively. There was nosignificant difference among the there groups. P=0.079.(4) The related factors of acute skin toxicities:1) Age: The patients divided into three groupsaccording to the age:≤35years,36-50years and≥51years. No statisticaldifference was found among the three group, P=0.476.2) Concurrentchemotherapy or not: There was no significant difference between the patientswith concurrent chemotherapy and those without, P=0.374.3) The volumesize of ipsilateral breast: The patients were divided into three groups:＜500cm3,500～1000cm3and＞1000cm3respectively. There was statisticaldifference was found among the three group, P=0.047.(5) Overall Survivaland patterns of failure: For all patients in this study, the median follow-up31.3months (range,1.9-56.8).To the last follow-up time, all patients werealive. There was no patient with recurrence or metastasis in the IMRT groupand SIB-IMRT group. But in the3DCRT group, a local recurrence occurredoutside primary tumor bed when she was re-examined23.1months aftersurgery and one patient was with metastasis of bilateral lung, bone andipsilateral superaclavical node metastasis22.0months after surgery. The2-year local control rate was98.3%;2-year disease-free survival rate was96.6%.(6) The duration of radiotherapy: The average time was51days in3DCRT group,48days in IMRT group and40days in SIB-IMRT group,which was the shortest among the three groups. There was statisticaldifference among the three groups, P=0.000.(7)For all31were3,8and20patients with3,4,5clips in their surgical cavity respectively. There were87.1%,64.5%,41.9%of the patients with surgical clips missed whenexpanding2.0cm,2.5cm and3.0cm around the surgical scar respectively. Theratio of covering clips were65.0%,75.5%and85.8%when2.0cm,2.5cmand3.0cm was expanded around the surgical scar respectively.Conclusions:1.SIB-IMRT after breast conserving surgery had similarsurvival rate,less acute skin toxicities and better cosmesis compared to3D-CRT plus electron boost or IMRT plus electron boost. The duration ofradiotherapy was the shortest.2. The volume size of ipsilateral breast affectsthe acute skin toxicities. The bigger the breast size, the more the skin toxicities.3. The tumor bed boost volume after expanding2-3cm around the surgical scar couldn't cover all of clips in surgical cavity after breast-conservingsurgery and may result in missing of tumor bed during the boost after wholebreast irradiation. Surgical clips should be used to outline the tumor bed boostvolume.