Division of Radiation Oncology, Department of Radiology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 9518510, Japan.
Breast Cancer. 2011 Oct;18(4):244-51. doi: 10.1007/s12282-010-0207-8. Epub 2010 May 11.
Most randomized comparison trials (RCTs) investigating treatments for brain metastases (BM) have included BM from any origin; as a result, more than half (52.4-77.0%) of the BM in these trials originated from the lungs (mostly non-small-cell lung cancer, NSCLC), with the breasts being the origin in only 6.8-19.0% of cases. In addition, patients with poor systemic status (KPS < 70) were not included in these trials. Hence, before we can apply RCT-based information to the daily clinical treatment of BM from breast cancers, it will be crucial to differentiate the characteristics of BM originating from NSCLC and BM originating from breast cancer. Although stereotactic radiosurgery (SRS) is widely used in Japan, level-1 evidence suggests that the benefit of using SRS in addition to whole-brain radiation therapy (WBRT) has been proven only for patients with a single BM. Treatment with SRS alone, which is widely used in Japan, seems attractive because it could avoid the risk of long-term adverse effects of WBRT. However, level-1 evidence suggests that the omission of WBRT results in a high frequency of brain tumor recurrence (BTR). In an RCT between SRS-alone and SRS + WBRT conducted in Japan, we found that patients who had a single BM and no extracranial metastases had a low risk of developing BTR after initial brain management (low-risk group) compared with those who had 2 or more BM and extracranial metastases (high-risk group). In order to meet the criteria of "low-risk" BTR, patients also should have good systemic status (KPS ≧ 70). Epidemiologic data suggest that the prognosis is twice as likely to be poor in patients with BM from breast cancer (RPA III = KPS < 70) than in patients with BM from NSCLC (40 vs. 20%); in addition, the probability of brain-only metastases in patients with breast cancer is less than half that in patients with NSCLC (20-25 vs. 60-75%). Considering these findings, we should be aware that most patients with BM from breast cancer are not good candidates for SRS alone, and, therefore, the role of WBRT is still important in the era of modern radiation techniques.
大多数研究脑转移瘤（BM）治疗的随机对照试验（RCT）都包括了来自任何部位的 BM；结果，这些试验中超过一半（52.4-77.0%）的 BM 来源于肺部（主要是非小细胞肺癌，NSCLC），只有 6.8-19.0%的 BM 来源于乳房。此外，这些试验未纳入一般状况较差（KPS<70）的患者。因此，在将基于 RCT 的信息应用于乳腺癌脑转移瘤的日常临床治疗之前，区分 NSCLC 来源的 BM 和乳腺癌来源的 BM 的特征至关重要。虽然立体定向放射外科（SRS）在日本被广泛应用，但 1 级证据表明，在全脑放疗（WBRT）的基础上联合 SRS 的治疗益处仅在单发 BM 患者中得到证实。单独使用 SRS 治疗在日本被广泛应用，似乎具有吸引力，因为它可以避免 WBRT 长期不良反应的风险。然而，1 级证据表明，不进行 WBRT 会导致脑肿瘤复发（BTR）的频率较高。在日本进行的 SRS 单独治疗与 SRS+WBRT 的 RCT 中，我们发现对于初始脑部管理后发生 BTR 风险较低的患者（低危组），与具有 2 个或更多 BM 和颅外转移的患者（高危组）相比，单发 BM 且无颅外转移的患者发生 BTR 的风险较低。为了满足“低危”BTR 的标准，患者还应具有良好的一般状况（KPS≥70）。流行病学数据表明，乳腺癌（RPA III=KPS<70）脑转移患者的预后比 NSCLC（40 vs. 20%）患者差一倍；此外，乳腺癌患者仅有脑转移的概率不到 NSCLC 患者的一半（20-25% vs. 60-75%）。考虑到这些发现，我们应该意识到，大多数乳腺癌脑转移瘤患者不适合单独使用 SRS，因此，在现代放射技术时代，WBRT 的作用仍然重要。
