Stage 4 breast cancer diagnoses rise over decade

De novo stage 4 breast cancer diagnoses increased significantly in the U.S. from 2010 to 2021, according to a cohort study published in JAMA Network Open.

Researchers analyzed 761,471 invasive breast cancer diagnoses from the Surveillance, Epidemiology, and End Results program. Among those cases, 43,934, or 5.8%, were stage 4 at diagnosis.

Stage 4 incidence rose from 9.5 cases per 100,000 females in 2010 to 11.2 cases per 100,000 females in 2021. That represented an annual percentage change of 1.2%.

Earlier-stage disease also increased during the study period. Incidence for stages 1 to 3 rose from 163.0 cases per 100,000 females in 2010 to 177.4 cases per 100,000 females in 2021.

Stage 4 incidence increased across tumor subtypes. Annual percentage change was 2.0% for HR-positive/ERBB2-negative disease, 1.6% for HR-positive/ERBB2-positive disease, and 2.7% for triple-negative breast cancer.

Among males, stage 4 incidence increased by 3.7% per year. Dana-Farber Cancer Institute noted that men accounted for less than 1% of breast cancer diagnoses in the study.

Overall survival improved over the study period for several stage 4 tumor subtypes. Changes for triple-negative breast cancer were not statistically significant, according to the study.

Sensitivity analyses restricted to 2010 to 2019 showed similar increasing trends, suggesting that the findings were not solely attributable to pandemic-related disruption.

The authors said further research is needed to determine factors contributing to increased stage 4 incidence, including changes in breast cancer natural history, screening, and other population-level factors.