三维近距离膜治疗在乳腺癌上臂皮肤环周侵犯应用的初步观察

Preliminary observation of superficial brachytherapy for the upper arm skin invasion of breast cancer

目的 探讨三维近距离膜治疗在乳腺癌上臂皮肤环周侵犯中的应用。方法 乳腺癌术后同侧胸壁、腋窝及锁骨上复发,同侧上臂皮肤及皮下软组织大面积环周受侵患者1例。对其上臂病变采用192Ir高剂量率近距离膜治疗,处方剂量50 Gy分25次,并与电子线计划进行比对,治疗过程中及治疗后观察疗效及不良反应。结果 三维近距离膜治疗与电子线的靶区剂量不均匀指数分别为1.62和1.94。三维近距离膜治疗CTV的D90、D100和V150%分别为205、163 cGy和6.3%,均高于电子线计划的D90、D100和V150%（189、110 cGy和3.23%）。三维近距离膜治疗肱骨的 D0.1、D1、D2分别为155、147、145 cGy,高于电子线计划的肱骨的80、55、36 cGy,但均远低于骨耐受剂量。该患接受近距离膜治疗后病灶部分消退,不良反应主要表现为2级皮肤反应。结论 对于诸如乳腺癌上臂环周受侵的浅表、大曲度靶区的照射,对比于电子线计划,选用近距离膜治疗实施简便均匀性好,可较好达到处方剂量,是一个行之有效的方法。

Objective To investigate the application of superficial brachytherapy in the treatment of the upper arm skin invasion of breast cancer. Methods This study was conducted on a female patient with ipsilateral chest wall, axillary, and clavicle recurrence, and circumferential skin and subcutaneous soft tissue invasion in the ipsilateral upper arm after modified radical mastectomy for breast cancer. The upper arm lesions were treated with 192Ir high-dose-rate superficial brachytherapy at a dose of 50 Gy in 25 fractions. Dosimetric parameters were compared between superficial brachytherapy and electron irradiation plan. Treatment outcomes and adverse reactions were observed during and after treatment. Results The heterogeneity index （HI） for target volume was 1.62 and 1.94 in superficial brachytherapy and electron irradiation plan, respectively. The D90, D100, and V150% for clinical target volume were higher in superficial brachytherapy than in electron irradiation plan （205 vs. 189 cGy;163 vs. 110 cGy;6.3% vs. 3.23%）. The D0.1, D1, and D2 for the humerus were also higher in superficial brachytherapy than in electron irradiation plan （155 vs. 80 cGy;147 vs. 55 cGy;145 vs. 36 cGy） and much lower than the bone tolerance dose in both treatments. The lesions partially subsidedafter superficial brachytherapy. The main adverse reaction was grade 2 radiation dermatitis. Conclusions Compared with electron irradiation plan, superficial brachytherapy is a simple and effective approach for irradiation of shallow target volume with a large curvature, such as circumferential upper arm skin invasion of breast cancer. Superficial brachytherapy achieves satisfactory homogeneity and dose distribution.