Trends in breast cancer death rates from ductal carcinoma in situ versus invasive cancer in the United States.

Background: Breast ductal carcinoma in situ (DCIS), considered a non-obligate precursor to invasive breast cancer, has been widely studied; however, trends in death rate from DCIS remain undocumented.

Methods: To examine the trend in death rate from DCIS among women (age at death, 40 + years) in the US, we quantified annual percent changes (APCs) and average APCs in age-standardized death rates using the Surveillance, Epidemiology, and End Results Program (SEER) 8 incidence-based mortality database and Joinpoint regression. The trend was quantified from 2000 to 2021, capturing deaths among women diagnosed between 1975 and 2021 and allowing for a 25-year follow-back period before each death year. Additionally, we employed the SEER 12 to assess disparities in death rates from DCIS by race and ethnicity during 2017-2021, based on diagnoses from 1992-2021. Trends in death rates from invasive breast cancer were analysed similarly.

Results: Death rate from DCIS increased by 2.43% annually (95% confidence interval [CI] = 1.34-3.54) from 2000-2015, and then plateaued, leading to an overall statistically non-significant increase from 2000-2021 (1.01% per year; 95%CI = -0.20-2.24). This trend was in stark contrast with an average of 1.61% annual decrease in death rates for invasive breast cancer (95%CI = -1.95 to -1.27). From 2016-2021, death rate from DCIS was 87% higher among non-Hispanic Black women than non-Hispanic White women (2.98 vs 1.60 per 100,000), a relatively larger disparity than the 39% estimated for death rate from invasive cancer (55.96 vs 40.28 per 100,000).

Conclusions: Distinct epidemiologic patterns in death rates between DCIS and invasive breast cancer highlight important implications for understanding the natural history and management of these malignancies.