乳腺癌乳房切除术后放疗患者内乳淋巴引流区非计划性受照剂量影响因素探讨

目的 探讨乳腺癌乳房切除术后放疗患者内乳淋巴引流区(IMN)非计划性照射时IMN受照剂量的影响因素。 方法 回顾性分析我院 138例乳腺癌根治术后接受胸壁 ±锁骨上下淋巴引流区放疗(3DCRT、正向IMRT或逆向IMRT)患者资料,依据RTOG标准勾画患侧IMN,获取IMN非计划性受照剂量。分析患者IMN非计划性照射时IMN受照剂量与患者临床特征及放疗技术特定参数的相关性。 结果 IMN非计划性受照剂量平均为32.85 Gy (2.76~50.93 Gy),7.3%患者达到了治疗剂量(≥45 Gy),且达到治疗剂量组的患者体重、体重指数、体表面积以及胸廓横径(DT)指标均低于未达到治疗组的患者,而包含在胸壁PTV内的内乳PTV体积(IMNin)及IMNin占IMN计划靶区体积的比例(RIMNin)要高于未达到治疗组的患者。多元线性回归分析结果显示,患者体重、胸廓前后径(DAP)、DT、RIMNin及PTV体积均是IMN非计划性受照剂量的影响因素(P=0.000、0.000、0.001、0.000、0.034)。 结论 乳房切除术后放疗的患者,IMN作为非计划靶区时,其受照剂量变化范围较大,部分患者可以达到治疗剂量,而且IMN非计划受照剂量受到患者某些体质特征、解剖学特征及放疗技术参数的影响,在进行相关研究设计或研究结果分析时对此应予以足够重视。

Influencing factors of dose coverage of unplanned irradiation of internal mammary lymph node drainage area in patients receiving radiotherapy after mastectomy

Objective To investigate the influencing factors of the dose coverage of unplanned internal mammary lymph node (IMN) irradiation in patients receiving chemotherapy after mastectomy. Methods Clinical data of 138 patients receiving radiotherapy in the upper and lower lymph node drainage area of the thoracic wall and clavicle [three-dimensional conformal radiotherapy (3DCRT),field-in-field forward intensity-modulated radiotherapy (F-IMRT) or inverse IMRT (I-IMRT)] were retrospectively analyzed. The IMN was delineated according to the Radiation Therapy Oncology Group (RTOG) criteria. The unplanned irradiation dose of the IMN was obtained. The correlation between the IMN irradiation dose,clinical characteristics and specific parameters of radiotherapy during the unplanned irradiation was statistically analysed. Results The mean dose of unplanned IMN irradiation was 32.85 Gy (range:2.76-50.93 Gy).In total,7.3% of breast cancer patients obtained the therapeutic dose of≥ 45 Gy. Body weight,body mass index (BMI),body surface area (BSA) and thoracic transverse diameter (DT) were lower,whereas the planning target volume of IMN (VIMN) included in the chest wall PTV (IMNin) and the ratio of IMNin to VIMN were higher compared with those of their counterparts with insufficient therapeutic dose. Multivariate regression analysis demonstrated that body weight,thoracic anteroposterior diameter (DAP),DT,RIMNin and PTV volume were the influencing factors of the dose coverage of unplanned IMN irradiation (P=0.000,0.000,0.001,0.000 and 0.034). Conclusions For patients receiving chemotherapy after mastectomy,the dose coverage significantly varies when the IMN is the unplanned target. Partial patients achieve the therapeutic dose. The dose coverage of unplanned IMN irradiation is influenced by physical characteristics,anatomical features and technical parameters of radiotherapy,which should be emphasized during the study design and result analysis.