诊断分期是癌症生存的关键预后因素。使用基于人群的数据，按国家、年龄组、日历周期和社会经济状况评估乳腺癌分期的全球分布。对 MEDLINE 和 Web of Science 数据库进行系统搜索，对2000年1月1日至2022年6月20日之间发表的文章或报告进行了登记网站和灰色文献。其中包括来自基于人群的癌症登记处的原发性乳腺癌（C50）个体诊断阶段的报告。研究特征符合条件的研究结果由两对评审员（J.D.B.F.、A.D.A.、A.M.、R.S. 和 F.G.）独立提取。提取特定阶段的比例，并评估癌症登记数据的质量和偏倚风险。使用最相关和高质量数据的分层规则计算国家汇总估计值，以避免重复。根据恶性肿瘤的 TNM 分类或监测、流行病学和最终结果，女性患乳腺癌的比例结果计划 [SEER]）阶段组。数据来自 81 个国家 240 万患有乳腺癌的女性。在全球范围内，撒哈拉以南非洲地区诊断时患有远处转移乳腺癌的病例比例较高，为 5.6% 至 30.6%，而北美则较低，为 0.0% 至 6.0%。过去20年，诊断患有远处转移性疾病的患者比例从约3.8%至35.8%（2000年代初）下降至3.2%至11.6%（2015年起），但也观察到稳定或略有增加。年龄较大和社会经济地位较低的患者被诊断为远处转移的病例所占比例最高，在较年轻的年龄组中为 2.0% 至 15.7%，在最年长的年龄组中为 4.1% 至 33.9%，在最弱势群体中为 1.7% 至 8.3%最弱势群体中的这一比例降至 2.8% 至 11.4%。有效的政策和干预措施已导致高收入国家诊断时诊断出患有转移性乳腺癌的女性比例下降，但不平等现象依然存在，需要通过提高对转移性乳腺癌的认识来解决乳腺癌症状和早期发现。提高基于人群的癌症登记的全球覆盖率和质量，包括收集标准化阶段数据，是监测进展的关键。

Stage at diagnosis is a key prognostic factor for cancer survival.To assess the global distribution of breast cancer stage by country, age group, calendar period, and socioeconomic status using population-based data.A systematic search of MEDLINE and Web of Science databases and registry websites and gray literature was conducted for articles or reports published between January 1, 2000, and June 20, 2022.Reports on stage at diagnosis for individuals with primary breast cancer (C50) from a population-based cancer registry were included.Study characteristics and results of eligible studies were independently extracted by 2 pairs of reviewers (J.D.B.F., A.D.A., A.M., R.S., and F.G.). Stage-specific proportions were extracted and cancer registry data quality and risk of bias were assessed. National pooled estimates were calculated for subnational or annual data sets using a hierarchical rule of the most relevant and high-quality data to avoid duplicates.The proportion of women with breast cancer by (TNM Classification of Malignant Tumors or the Surveillance, Epidemiology, and End Results Program [SEER]) stage group.Data were available for 2.4 million women with breast cancer from 81 countries. Globally, the proportion of cases with distant metastatic breast cancer at diagnosis was high in sub-Saharan Africa, ranging from 5.6% to 30.6% and low in North America ranging from 0.0% to 6.0%. The proportion of patients diagnosed with distant metastatic disease decreased over the past 2 decades from around 3.8% to 35.8% (early 2000s) to 3.2% to 11.6% (2015 onwards), yet stabilization or slight increases were also observed. Older age and lower socioeconomic status had the largest proportion of cases diagnosed with distant metastatic stage ranging from 2.0% to 15.7% among the younger to 4.1% to 33.9% among the oldest age group, and from 1.7% to 8.3% in the least disadvantaged groups to 2.8% to 11.4% in the most disadvantaged groups.Effective policy and interventions have resulted in decreased proportions of women diagnosed with metastatic breast cancer at diagnosis in high-income countries, yet inequality persists, which needs to be addressed through increased awareness of breast cancer symptoms and early detection. Improving global coverage and quality of population-based cancer registries, including the collection of standardized stage data, is key to monitoring progress.