In a study reported in JAMA Network Open, Xu et al identified incidence of primary invasive breast cancer according to race/ethnicity, disease stage, and hormone receptor status among U.S. women with breast cancer aged 20 to 49 years diagnosed between 2000 and 2019.
Study Details
The study used data from 17 registries of the SEER (Surveillance, Epidemiology, and End Results) program on women aged 20 to 49 years diagnosed from 2000 to 2019.
Key Findings
Among 217,815 eligible women included in the analysis, 126,960 (58.3%) were White; 37,048 (17.0%) were Hispanic; 27,112 (12.4%) were Black; 25,210 (11.6%) were Asian or Pacific Islander; and 1,485 (0.7%) were American Indian or Alaskan Native. Regarding hormone receptor status, the majority of women had estrogen receptor (ER)-positive/progesterone receptor (PR)-positive disease (61.5%). Regarding tumor stage, the majority had stage I (37.6%) or stage II (37.3%) disease.
Overall, breast cancer incidence rates increased by 0.79% (95% confidence interval [CI] = 0.42%–1.15%) each year over the study period, with increasing trends observed in almost all racial/ethnic groups. The overall incidence increased by 0.24% (95% CI = 0.05%–0.42%) per year between 2000 and 2016, and more markedly, by 3.76% (95% CI = 1.39%–6.19%), each year from 2016 and after.
Overall, average annual incidence rates increased by 3.45% and 3.39% for stage I and IV disease, respectively, and decreased by 3.42% and 3.06% for stage II and III disease, respectively. Over the study period, age-standardized incidence rates increased for ER-positive/PR-positive (average annual percent change [AAPC] = 2.72%) and ER-positive/PR-negative tumors (AAPC = 1.43%) and decreased for ER-negative/PR-positive (AAPC = −3.25%) and ER-negative/PR-negative tumors (AAPC = −0.55%).
Age-standardized incidence rates were highest among Black women aged 20 to 29 years (incidence rate ratio [IRR] = 1.53 vs White women) and highest among Black women aged 30 to 39 years (IRR = 1.15 vs White women); among women aged 40 to 49 years, the incidence rate ratio for Black vs White women was 0.96. Age-period-cohort analysis demonstrated both cohort and period effects on breast cancer incidence (P < .001).
The investigators concluded, “In this population-based cross-sectional analysis, an increase in breast cancer incidence rates among young U.S. women and age-related crossover between non-Hispanic White and Black women were observed. Prevention efforts in young women need to adopt a targeted approach to address racial disparities in incidence rates observed at different age phases.”
Adetunji T. Toriola, MD, PhD, MPH, of the Department of Surgery, Division of Public Health Sciences, Washington University School of Medicine in St. Louis, is the corresponding author for the JAMA Network Open article.
Disclosure: The study was supported by the National Cancer Institute. For full disclosures of the study authors, visit jamanetwork.com.
