药物相关性颌骨坏死 (MRONJ) 是抗骨吸收治疗最重要的毒性之一，这是乳腺癌和骨转移患者的标准治疗方法。然而，基于人群的 MRONJ 发病率尚未明确。因此，我们进行了一项回顾性多中心研究，以评估整个奥地利联邦州（蒂罗尔州）的发病率。这项回顾性多中心研究于 2000 年至 2020 年间在奥地利蒂罗尔州的所有 9 个乳腺中心进行。利用癌症登记处，对蒂罗尔总人口中的所有乳腺癌患者进行了筛查。所有接受抗骨吸收治疗的乳腺癌和骨转移患者最终均纳入研究。从最初筛选的 8,860 名患者中，639 人符合条件并纳入我们的研究。患者每月接受一次抗骨吸收治疗，无需降级治疗。 56 名患者（8.8%，95% CI，6.6 至 11.0）被诊断为 MRONJ。仅接受狄诺塞麦治疗的个体中，MRONJ 的发生率为 11.6%（95% CI，8.0 至 15.3）；仅接受双磷酸盐治疗的个体中，MRONJ 的发生率为 2.8%（95% CI，0.7 至 4.8）；仅接受双磷酸盐治疗的个体中，MRONJ 的发生率为 16.3%（95% CI，8.8）。到 23.9）在接受双磷酸盐然后接受狄诺塞麦的组中。使用狄诺塞麦治疗时，个体出现 MRONJ 的时间明显更早。开始治疗后出现 MRONJ 的时间对于仅接受狄诺塞麦治疗的个体而言为 4.6 年，对于仅接受双磷酸盐治疗的个体而言为 5.1 年，对于连续接受两种治疗的个体而言为 8.4 年。发现患有骨转移的乳腺癌患者的 MRONJ 发生率相当高，特别是对于接受狄诺塞麦的患者，与文献中的现有数据相比。此外，接受狄诺塞麦治疗的患者明显更早出现 MRONJ。

Medication-related osteonecrosis of the jaw (MRONJ) is one of the most important toxicities of antiresorptive therapy, which is standard practice for patients with breast cancer and bone metastases. However, the population-based incidence of MRONJ is not well established. We therefore performed a retrospective multicenter study to assess the incidence for a whole Austrian federal state (Tyrol).This retrospective multicenter study was conducted between 2000 and 2020 at all nine breast centers across Tyrol, Austria. Using the cancer registry, the total Tyrolean population was screened for all patients with breast cancer. All patients with breast cancer and bone metastases receiving antiresorptive therapy were finally included in the study.From 8,860 patients initially screened, 639 individuals were eligible and included in our study. Patients received antiresorptive therapy once per month without de-escalation of therapy. MRONJ was diagnosed in 56 (8.8%, 95% CI, 6.6 to 11.0) patients. The incidence of MRONJ was 11.6% (95% CI, 8.0 to 15.3) in individuals treated with denosumab only, 2.8% (95% CI, 0.7 to 4.8) in those treated with bisphosphonates only, and 16.3% (95% CI, 8.8 to 23.9) in the group receiving bisphosphonates followed by denosumab. Individuals developed MRONJ significantly earlier when treated with denosumab. Time to MRONJ after treatment initiation was 4.6 years for individuals treated with denosumab only, 5.1 years for individuals treated with bisphosphonates only, and 8.4 years for individuals treated with both consecutively.MRONJ incidence in breast cancer patients with bone metastases was found to be considerably higher, especially for patients receiving denosumab, when compared with available data in the literature. Additionally, patients treated with denosumab developed MRONJ significantly earlier.