Dosimetric comparison of accelerated partial breast irradiation and whole breast irradiation with simultaneous integrated boost intensity modulated radiotherapy after breast-conserving surgery for early breast cancer / 肿瘤研究与临床

ABSTRACT

Objective:To compare the dosimetric differences between accelerated partial breast irradiation intensity modulated radiation therapy (APBI-IMRT) and whole breast irradiation with simultaneous integrated boost intensity modulated radiotherapy (WBI-SIB-IMRT) for early-stage breast cancer after breast-conserving surgery.Methods:A total of 35 patients with early-stage breast cancer in Jilin Province Cancer Hospital between July 2009 and December 2014 after breast-conserving surgery were enrolled. The targeted regions of APBI-IMRT and WBI-SIB-IMRT were created for each patient. The dosimetric difference comparison of the targeted region and normal tissues was evaluated by using dose volume histogram (DVH).Results:There was no significant difference in the dosimetric comparison of gross tumor volume (GTVtb) and planning gross tumor volume (PGTVtb) after correction of cumulative radiation effect (CRE) between WBI-SIB-IMRT group and APBI-IMRT group (both P > 0.05). The dose of clinical target volume (CTV) and planning target volume(PTV) in APBI-IMRT group was higher than that in WBI-SIB-IMRT group [CTV (4 720±71) cGy vs. (3 889±79) cGy, t = 3.184, P = 0.027; PTV (4 675±164) cGy vs. (3 807±199) cGy, t = 2.751, P = 0.032] after CRE correction. Compared with WBI-SIB-IMRT group, the dose of ipsilateral lung tissue and left heart tissue in APBI-IMRT group was decreased after CRE correction [(558.5±8.9) cGy vs. (1 304.9±34.4) cGy, t = -7.328, P = 0.001; (35.5±5.3) cGy vs. (843.0±41.5) cGy, t = -8.137, P = 0.001]. V 5/3.6 Gy, V 10/7.3 Gy, V 15/10.9 Gy, V 20/14.6 Gy, V 25/18.2 Gy and V 30/21.9 Gy of the ipsilateral lung and V 30/21.9Gy, V 40/29.2Gy of left heart in all breast cancer patients after two chemotherapy treatments had significant differences (all P = 0.001). Conclusion:Compared with WBI-SIB, APBI-IMRT can improve the dose distribution in target area and reduce the volume of high dose irradiation in organs at risk.