Global Stage Distribution of Breast Cancer at Diagnosis

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. Data Sources: 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. Study Selection: Reports on stage at diagnosis for individuals with primary breast cancer (C50) from a population-based cancer registry were included. Data Extraction and Synthesis: 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. Main Outcomes and Measures: The proportion of women with breast cancer by (TNM Classification of Malignant Tumors or the Surveillance, Epidemiology, and End Results Program [SEER]) stage group.