Lotayef M M, Barsoum M S, Zaki O E, Nasr M A, Abdel Aziz R A, Koteb M, Radwan A
The Department Radiation Oncology, National Cancer Institute, Cairo University.
J Egypt Natl Canc Inst. 2005 Sep;17(3):203-10.
Internal mammary irradiation is still an issue of great debate. Although treatment of internal mammary lymph nodes was routinely given in the majority of randomized trials, data in its value are still limited. The aim of this study is to determine the variability of position of the internal mammary lymph nodes using lymphoscintigraphy and to compare the dose of radiation that reaches these lymph nodes, the heart and lungs if only tangential fields are used.
This is a prospective study that included 30 breast cancer patients treated in the department of radiation oncology of the Egyptian National Cancer Institute, Cairo University, planned for postoperative radiotherapy. Lymphoscintigraphy was done for all patients for detection of the exact site of the internal mammary lymph nodes. Dose volume histogram (DVH) was done to measure the dose to the heart using CT planning. Two plans were done for each patient, the first with internal mammary field (plan I), and the second without but with contralateral crossing of the midline by 1cm (plan II).
The mean percentage of the internal mammary lymph nodes included in the internal mammary field (plan I) was 70.03% while in plan II it was 3.05%. The mean dose percentage reaching the heart in plan I was 54.5% of total dose, while in plan II it was 9.16% of total dose with significant p value<0.001. The mean dose to the heart decreased as the heart volume increased, this significant difference between the 2 plans was maintained for the different heart volumes. Also, the radiation dose to the heart in plan I varied significantly (p: 0.001) between the right side vs the left side with a mean dose of 48.02% and 63.5%, respectively. The mean dose percentage reaching the lungs in plan I and plan II was 46.53% and 24.5% respectively, with significant p value<0.001.
If irradiation of internal mammary chain is intended, then a direct internal mammary field should be used. The planning of internal mammary field should be adjusted according to lymphoscintigraphy so as to include most of the draining internal mammary lymph nodes. The risk of late cardiac and pulmonary complications will increase when using direct internal mammary field, but the risk of cardiac complications will be less in irradiation of right side internal mammary lymph nodes compared to that of irradiation of the left side.
内乳照射仍是一个极具争议的问题。尽管在大多数随机试验中常规对内乳淋巴结进行治疗，但其价值的数据仍然有限。本研究的目的是使用淋巴闪烁显像术确定内乳淋巴结位置的变异性，并比较仅使用切线野时到达这些淋巴结、心脏和肺部的辐射剂量。
这是一项前瞻性研究，纳入了开罗大学埃及国家癌症研究所放射肿瘤学部门治疗的30例乳腺癌患者，计划进行术后放疗。对所有患者进行淋巴闪烁显像术以检测内乳淋巴结的确切位置。使用CT规划进行剂量体积直方图（DVH）分析以测量心脏所接受的剂量。为每位患者制定两个计划，第一个计划包括内乳野（计划I），第二个计划不包括内乳野，但对侧中线交叉1cm（计划II）。
内乳野（计划I）所包括的内乳淋巴结的平均百分比为70.03%，而在计划II中为3.05%。计划I中到达心脏的平均剂量百分比为总剂量的54.5%，而在计划II中为总剂量的9.16%，p值具有显著性差异<0.001。随着心脏体积增加，心脏所接受的平均剂量降低，这两个计划之间的显著差异在不同心脏体积情况下均保持。此外，计划I中右侧和左侧心脏所接受的辐射剂量差异显著（p：0.001），平均剂量分别为48.02%和63.5%。计划I和计划II中到达肺部的平均剂量百分比分别为46.53%和24.5%，p值具有显著性差异<0.001。
如果打算对内乳链进行照射，则应使用直接的内乳野。内乳野的规划应根据淋巴闪烁显像术进行调整，以便包括大部分引流的内乳淋巴结。使用直接内乳野时，晚期心脏和肺部并发症的风险将会增加，但与左侧内乳淋巴结照射相比，右侧内乳淋巴结照射时心脏并发症的风险更低。
