乳腺癌保乳术后放射治疗中腋窝各站淋巴结实际覆盖剂量的研究

An analysis of the incidental irradiation to the axillary levels Ⅰ-Ⅲ lymph node during radiotherapy after breast conserving surgery

目的 研究乳腺癌保乳保腋窝术后分别采用常规切线野（CTF）、三维适形放疗（3D-CRT）和正向调强放疗（IMRT）技术放疗中Ⅰ站、Ⅱ站和Ⅲ站腋窝淋巴结覆盖剂量。方法 回顾分析连续42例仅行前哨淋巴结活检（SLNB）而未行腋窝淋巴结清扫的乳腺癌保乳术后T1-2N0M0期患者。按照放射治疗肿瘤协作组（RTOG）标准勾画Ⅰ站、Ⅱ站和Ⅲ站腋窝淋巴结引流区。每位患者均制定全乳＋腋窝CTF、3D-CRT和IMRT 3种放疗计划，处方剂量为50 Gy/25次，分析腋窝淋巴结覆盖剂量。结果 CTF、3D-CRT和IMRT放疗计划腋窝各站受照剂量不同，I站累及平均剂量分别为（40.1±6.8）、（35.4±8.3）和（32.9±7.0）Gy（F=10.269，P〈0.05），Ⅱ站分别为（33.2±7.1）、（30.6±6.7）和（30.4±7.0）Gy（P〉0.05），Ⅲ站分别为（9.6±6.8）、（6.4±4.5）和（5.2±3.7）Gy（F=8.377，P〈0.05）。腋窝各站接受相同处方剂量的体积不同，I站V50（接受50 Gy处方剂量体积）分别为21.3%、27.6%和9.6%（F=13.161，P〈0.05），Ⅱ站V50分别为12.9%、15.9%和8.3%（P〉0.05），Ⅲ站V50分别为0.4%、0.1%和0（P〉0.05）。结论 早期乳腺癌保乳保腋窝术后采用CTF、3D-CRT和IMRT 3种放疗技术时腋窝Ⅰ站、Ⅱ站和Ⅲ站淋巴结引流区覆盖剂量有限，因此对于发现腋窝微转移、但未清扫腋窝的患者，应充分评估腋窝淋巴结转移风险，制定个体化放疗计划。

Objective To evaluate the incidental irradiation to the axillary levels Ⅰ,Ⅱ and Ⅲ during 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 T1-2N0M0 stage 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 levels Ⅰ-Ⅲ were 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.