Harvard Radiation Oncology Program, Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA.
Breast. 2009 Oct;18 Suppl 3:S103-11. doi: 10.1016/S0960-9776(09)70284-X.
The EBCTCG has clearly demonstrated that the use of RT after either breast conserving surgery (BCS) or after mastectomy in node-positive patients not only reduces local recurrence (LR), but also improves long-term survival. The EBCTCG specifically found that the absolute reduction in the 5-year rate of LR was proportional to the absolute reduction in 15-year breast cancer mortality with a 4:1 ratio. Studies from the EBCTCG have also clearly shown that when RT for breast cancer inadvertently delivers 'excessive' dose to the heart, there is an increased rate of late cardiac deaths. Over time, LR rates with RT have decreased, particularly after BCS, and this is largely due to a favorable interaction of RT with adjuvant systemic therapy. There is new information emerging about the effectiveness of RT based on newer biologic classification of breast cancer and about how the 4:1 ratio might change in the face of increasingly effective systemic therapy and with a better understanding of the importance of biologic classification and of the competing risks of local and distant recurrence. Technical innovations in RT include the development of techniques that minimize cardiac irradiation. It is critical that CT simulation be done during which the heart should be contoured and the radiation dose-cardiac volume relationship be determined. In the EBCTCG's preliminary analysis, increased late cardiac deaths were most closely linked to mean cardiac doses >5 Gy. A number of techniques are available to minimize cardiac dose both after BCS and mastectomy and these will be described. There has also been development of fractionation and treatment techniques to complete RT faster for purposes of patient convenience and to assure its optimal level of use. There are now 10-year results from a Canadian trial showing equivalent LR and cosmetic outcome with RT using the conventional 25 treatments to the whole breast compared to 16 treatments using a higher dose per day. Few randomized patients, however, were treated with adjuvant chemotherapy and a boost was not used. The generalizability of the Canadian trial results to patients treated with adjuvant chemotherapy or requiring a boost is not known. For patients treated after BCS, there has been great interest in the use of accelerated partial breast irradiation (APBI), which can be accomplished using interstitial, intracavitary, external-beam or intraoperative techniques. Clinical trials are now underway to compare APBI to conventional techniques, but mature results from these trials will not be available for some time. In the U.S., ASTRO has developed a consensus statement based on an expert panel as to when APBI can be reasonably used outside of a clinical trial and this will be described.
EBCTCG 明确表明，在淋巴结阳性患者中，无论是在保乳手术后还是在乳房切除术后使用放疗，不仅可以降低局部复发率（LR），还可以改善长期生存。EBCTCG 特别发现，LR 五年发生率的绝对降低与 15 年乳腺癌死亡率的绝对降低成比例，比例为 4:1。EBCTCG 的研究还明确表明，当乳腺癌放疗无意中对心脏给予“过量”剂量时，晚期心脏死亡的发生率会增加。随着时间的推移，接受放疗的 LR 率下降，特别是在保乳手术后，这主要是由于放疗与辅助全身治疗的有利相互作用。基于乳腺癌新的生物学分类，以及随着对系统治疗效果的提高以及对生物学分类的重要性和局部与远处复发的竞争风险的更好理解，出现了有关放疗有效性的新信息。放疗技术的创新包括开发可最大限度减少心脏辐射的技术。在进行 CT 模拟时，至关重要的是要对心脏进行轮廓勾勒并确定辐射剂量-心脏体积关系。在 EBCTCG 的初步分析中，晚期心脏死亡的增加与平均心脏剂量>5 Gy 最密切相关。有多种技术可用于在保乳术和乳房切除术后降低心脏剂量，将对这些技术进行描述。还开发了分割和治疗技术，以便为了患者的方便并确保其最佳使用水平而更快地完成 RT。目前，加拿大的一项试验结果显示，在使用常规的 25 次全乳照射治疗与每天使用更高剂量的 16 次照射治疗相比，局部复发和美容效果相当。但是，很少有随机患者接受辅助化疗，也没有使用加量照射。加拿大试验结果对接受辅助化疗或需要加量照射的患者的普遍性尚不清楚。对于接受保乳术后治疗的患者，加速部分乳腺照射（APBI）的使用引起了极大的兴趣，APBI 可以通过间质内、腔内、外照射或术中技术来实现。目前正在进行临床试验以比较 APBI 与常规技术，但这些试验的成熟结果在一段时间内无法获得。在美国，ASTRO 根据专家组的意见制定了一份共识声明，阐述了在临床试验之外合理使用 APBI 的情况，本文将对此进行描述。
