A study presented at the 2023 San Antonio Breast Cancer Symposium reported a significant increase in the incidence and proportion of Stage IV (metastatic) breast cancer diagnoses among women in the United States from 2010 to 2019, with a notable rise in younger age groups. Researchers analyzed 2,235,934 invasive breast cancer cases from the National Cancer Database during this period to identify trends.
The overall incidence of Stage IV breast cancer increased from 3.03% to 4.14% from 2010-2019, while the proportion of Stage IV cases among all breast cancer diagnoses rose from 4.2% to 6.3% over the decade. Women aged 20-29 experienced the greatest increase in incidence, from 2.9% to 4.5%, and the largest jump in proportion of Stage IV cases was observed in women aged 40-49, from 4.2% to 6.9%. The median age at Stage IV diagnosis remained stable at 60.
Stage IV diagnoses were found to be more prevalent in younger women, Black women, and those with higher socioeconomic status, larger or higher-grade tumors, and triple-negative or HER2-positive breast cancer subtypes. Significant increases in Stage IV diagnoses were observed across all racial/ethnic groups and all tumor subtypes. This study provides a critical baseline for further investigation into the factors contributing to the rising rates of metastatic breast cancer.
