An analysis of the incidental irradiation to the axillary levelsⅠ-Ⅲlymph node during radiotherapy after breast conserving surgery / 中华放射医学与防护杂志

ABSTRACT

Objective To evaluate the incidental irradiation to the axillary levels Ⅰ,Ⅱ and Ⅲduring the whole breast radiotherapy after breast conserving surgery(BCS)without axillary lymph node dissection(ALND)in breast cancer(BC)patients.Methods A retrospective analysis was performed on the consecutive 42 cases of T1-2N0M0stage BC patients with sentinel lymphnode biopsy(SLNB)and BCS but without ALND.The axillary lymph nodes of Ⅰ,Ⅱ and Ⅲ were delineated according to RTOG atlas guideline.Three radiotherapy plans including conventional tangential field(CTF),three-dimensional conformal radiotherapy(3D-CRT)and forward-planned intensity-modulated radiotherapy(IMRT)for whole breast irradiation were devised for each case.The Prescription dose was 50 Gy per 25 fractions.Doses to axillary levels(Ⅰ-Ⅲ)were evaluated.Results The mean doses delivered to axillary by the three techniques(CTF,3D-CRT and IMRT)were(40.1 ±6.8),(35.4 ±8.3),(32.9 ±7.0)Gy for level Ⅰ(F＝10.269,P＜0.05),(33.2 ±7.1),(30.6 ±6.7),(30.4 ±7.0)Gy for level Ⅱ(P＞0.05)and(9.6 ±6.8),(6.4 ±4.5),(5.2 ±3.7)Gy for level Ⅲ(F ＝8.377,P ＜0.05),respectively.V50(volume receiving 50 Gy)for the three techniques were 21.3％,27.6％,9.6％for level Ⅰ(F＝13.161,P＜0.05),12.9％,15.9％,8.3％for level Ⅱ(F＝2.750,P＜0.05)and 0.4％,0.1％and 0％for level Ⅲ(P＞0.05),respectively.Conclusions The doses coverage to axillary levelsⅠ-Ⅲwere all limited in the three techniques.Therefore,it is necessary to assess the risk of axillary lymph node metastasis adequately to develop individualized radiotherapy plans.