多个随机试验已经确立了早期乳腺癌中术后辅助内分泌治疗（ET）和乳腺整体照射（WBI）作为保留乳房手术（BCS）后的标准方法。多个试验研究了省略WBI的效果，结果显示缺失了局部控制，但生存率仍然保持不变，因此已经被多个指南中采用作为特定患者的治疗选择。省略WBI而不是ET也可能是一种有价值的选择，因为这两种治疗的副作用明显不同。然而，BCS + ET与BCS + WBI之间的临床结果尚未得到正式分析。我们进行了系统文献回顾，搜索并筛选了2000年以后发表的在低风险乳腺癌患者中比较BCS + ET与BCS + WBI的随机试验。我们排除了使用任何形式化疗、局部淋巴放疗和乳房切除术的试验。我们采用了两步法进行荟萃分析。首先，我们提取了所有可用的发表事件率和效应大小，作为研究终点进行了总体和乳腺癌特异性生存率（OS、BCSS）、局部（LR）和区域复发、无病生存率、远处转移无病间隔、对侧乳腺癌和除乳腺癌外的第二癌以及乳房切除术间隔的比较，通过网络荟萃分析进行了比较。其次，我们使用了早期乳腺癌试验协作组（EBCTCG）的发表的个体患者数据，以比较OS和BCSS。我们确定了三项研究，其中一项直接比较了BCS + ET与BCS + WBI（n = 1059），另外九项研究对额外的7207名患者进行了BCS或BCS + WBI + ET的随机分组，从而可以进行四组比较。在网络分析中，LR在BCS + WBI组中明显低于BCS + ET组（HR = 0.62; CI-95%：0.42-0.92; p = 0.019）。我们未发现OS（HR = 0.93; CI-95%：0.53-1.62; p = 0.785）和BCSS（OR = 1.04; CI-95%：0.45-2.41; p = 0.928）之间的任何差异。此外，我们发现在BCS + WBI组中，远处转移无病间隔更短，对侧乳腺癌的发生率更高，乳房切除术间隔更短。使用EBCTCG数据，BCS + ET与BCS + WBI在10年后的OS和BCSS之间没有显著差异（OS：OR = 0.85; CI-95%：0.59-1.22; p = 0.369）（BCSS：OR = 0.72; CI-95%：0.38-1.36; p = 0.305）。直接和间接比较的证据表明，BCS + WBI可能是一种与BCS + ET相当的逐步缩减策略，适用于低风险乳腺癌。还需进一步比较这两种方法之间的不良事件和生活质量评估。

Multiple randomized trials have established adjuvant endocrine therapy (ET) and whole breast irradiation (WBI) as the standard approach after breast-conserving surgery (BCS) in early-stage breast cancer. The omission of WBI has been studied in multiple trials and resulted in reduced local control with maintained survival rates and has therefore been adapted as a treatment option in selected patients in several guidelines. Omitting ET instead of WBI might also be a valuable option as both treatments have distinctly different side effect profiles. However, the clinical outcomes of BCS + ET vs. BCS + WBI have not been formally analyzed.We performed a systematic literature review searching for randomized trials comparing BCS + ET vs. BCS + WBI in low-risk breast cancer patients with publication dates after 2000. We excluded trials using any form of chemotherapy, regional nodal radiation and mastectomy. The meta-analysis was performed using a two-step process. First, we extracted all available published event rates and the effect sizes for overall and breast-cancer-specific survival (OS, BCSS), local (LR) and regional recurrence, disease-free survival, distant metastases-free interval, contralateral breast cancer, second cancer other than breast cancer and mastectomy-free interval as investigated endpoints and compared them in a network meta-analysis. Second, the published individual patient data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) publications were used to allow a comparison of OS and BCSS.We identified three studies, including a direct comparison of BCS + ET vs. BCS + WBI (n = 1059) and nine studies randomizing overall 7207 patients additionally to BCS only and BCS + WBI + ET resulting in a four-arm comparison. In the network analysis, LR was significantly lower in the BCS + WBI group in comparison with the BCS + ET group (HR = 0.62; CI-95%: 0.42-0.92; p = 0.019). We did not find any differences in OS (HR = 0.93; CI-95%: 0.53-1.62; p = 0.785) and BCSS (OR = 1.04; CI-95%: 0.45-2.41; p = 0.928). Further, we found a lower distant metastasis-free interval, a higher rate of contralateral breast cancer and a reduced mastectomy-free interval in the BCS + WBI-arm. Using the EBCTCG data, OS and BCSS were not significantly different between BCS + ET and BCS + WBI after 10 years (OS: OR = 0.85; CI-95%: 0.59-1.22; p = 0.369) (BCSS: OR = 0.72; CI-95%: 0.38-1.36; p = 0.305).Evidence from direct and indirect comparison suggests that BCS + WBI might be an equivalent de-escalation strategy to BCS + ET in low-risk breast cancer. Adverse events and quality of life measures have to be further compared between these approaches.