Cohort study of time trends in incidence and survival of individuals diagnosed with de novo stage IV breast cancer, 2010-2021

A population-based cohort study using the SEER database evaluated incidence, percentage, and survival of individuals diagnosed with de novo stage IV breast cancer diagnosed from 2010 through 2021. Among 761 471 breast cancer diagnoses (median age at diagnosis 60 years; IQR 50-70; 99.2% female), 43 934 (5.8%) were stage IV. Stage IV incidence increased from 9.5 per 100 000 females in 2010 to 11.2 per 100 000 females in 2021, an annual percentage change of 1.2% (95% CI 0.8-1.6). The incidences of stage I to III disease also increased (163.0 to 177.4 per 100 000 females). Stage IV incidence increased across all tumor subtypes and across all ages, races and sexes. Survival of de novo stage IV breast cancer improved significantly from 2010 through 2021. The authors conclude that these findings suggest that efforts are needed to determine factors contributing to these increases in incidence and to identify breast cancer before patients present with de novo stage IV disease.