<p>Risk of bias in included studies.</p>

This meta-analysis aimed to determine the effect of deep inspiration breath hold (DIBH) compared with free breathing (FB) on dose to the organs at risk (OARs), such as the heart, left anterior descending (LAD) coronary artery, lungs, and contralateral breast, in patients with left-sided breast cancer treated with volumetric modulated arc therapy (VMAT). PubMed, EMBASE, and Cochrane Library electronic databases were searched for studies until March 21, 2024. Cochrane RevMan version 5.4 statistical software was used to analyze 11 eligible studies. Standard mean difference (SMD), with 95% confidence interval for OAR dose reductions, was calculated. DIBH considerably resulted in lower mean doses (Dmean) to the heart (SMD = −1.40 Gy), LAD (SMD = −1.65 Gy), ipsilateral lung (SMD = −0.57 Gy), contralateral lung (SMD = −0.46 Gy), and contralateral breast (SMD = −0.20 Gy). If VMAT was delivered with an arc of >180O, the heart Dmean reduction was even more pronounced. Subgroup analysis revealed that DIBH efficiently reduced heart Dmean, especially in patients with tumor bed boost without nodal irradiation. DIBH was effective in reducing dose to OARs in patients treated with VMAT in all subgroups, i.e., breast only, with/without tumor bed boost, and with/without nodal irradiation. Furthermore, the use of DIBH is strongly recommended for patients undergoing VMAT with a tumor bed boost or without nodal irradiation, as it is more effective in reducing heart Dmean than FB.本荟萃分析旨在探讨接受容积调强弧形治疗（volumetric modulated arc therapy, VMAT）的左侧乳腺癌患者中，深吸气屏气（deep inspiration breath hold, DIBH）相较于自由呼吸（free breathing, FB）对心脏、左前降支冠状动脉、肺脏及对侧乳腺等危及器官（organs at risk, OARs）受照剂量的影响。研究检索了PubMed、EMBASE及Cochrane Library电子数据库，检索时限截至2024年3月21日。采用Cochrane RevMan 5.4版统计软件对11项符合纳入标准的研究进行荟萃分析，计算了危及器官剂量降低的标准均数差（standard mean difference, SMD）及95%置信区间。结果显示，DIBH可显著降低心脏（SMD=−1.40 Gy）、左前降支冠状动脉（SMD=−1.65 Gy）、同侧肺（SMD=−0.57 Gy）、对侧肺（SMD=−0.46 Gy）及对侧乳腺（SMD=−0.20 Gy）的平均剂量（mean doses, Dmean）。当VMAT采用大于180°的弧野实施时，心脏平均剂量的降低效果更为显著。亚组分析表明，DIBH可有效降低心脏平均剂量，尤其在接受瘤床推量且未行淋巴结照射的患者中效果更为突出。在所有亚组（仅乳腺照射、伴/不伴瘤床推量、伴/不伴淋巴结照射）中，DIBH均可有效降低接受VMAT治疗患者的危及器官受照剂量。此外，对于接受VMAT治疗且行瘤床推量或未行淋巴结照射的患者，强烈推荐采用DIBH，因其相较于FB可更有效地降低心脏平均剂量。