Increasing Rates of Distant-Stage Breast Cancer at Presentation in U.S. Women

Oncology Medicine
breast cancer distant-stage cancer incidence rates U.S. women COVID-19 screening racial disparities

Report on the Increasing Rates of Distant-Stage Breast Cancer in U.S. Women

Academic Background

Breast cancer is the second leading cause of cancer death among U.S. women, following lung cancer. Although screening mammography has been shown to significantly reduce breast cancer mortality, screening rates in the U.S. remain low, particularly among women aged 40 and older, with rates declining from 70% in 2000 to 64% in 2015, and slightly recovering to 67.5% in 2019. Early detection of breast cancer is closely linked to treatment success and survival rates, and the stage of the tumor at diagnosis significantly impacts survival. The five-year survival rate for localized invasive breast cancer is 99%, while for distant-stage (metastatic) breast cancer, it is only 31%.

In recent years, particularly during the COVID-19 pandemic in 2020, breast cancer screening and diagnostic procedures were severely disrupted, leading to a decline in breast cancer diagnosis rates. Delayed diagnosis may result in more advanced disease at the time of diagnosis, thereby affecting treatment outcomes. Therefore, studying trends in the incidence of distant-stage breast cancer, especially changes during the COVID-19 pandemic, is of significant public health importance.

Source of the Paper

This report was authored by Dr. R. Edward Hendrick and Dr. Debra L. Monticciolo, from the Department of Radiology at the University of Colorado School of Medicine and the Foundation for Imaging Research and Education, respectively. The paper was published in December 2024 in the journal Radiology, titled Surveillance, Epidemiology, and End Results Data Show Increasing Rates of Distant-Stage Breast Cancer at Presentation in U.S. Women.

Research Process

Study Design

This retrospective study utilized data from the Surveillance, Epidemiology, and End Results (SEER) 22 database of the National Cancer Institute. The database covers cancer registry data from 22 regions in the U.S. from 2004 to 2021, representing 47.9% of the U.S. population and involving approximately 71 to 80 million women annually.

Data Processing

The study analyzed stage-specific breast cancer incidence data from the SEER 22 database for the period 2004 to 2021, using Joinpoint software to evaluate trends in distant-stage breast cancer incidence among U.S. women overall, by age group, and by race and ethnicity. The data were delay-adjusted and age-adjusted to ensure accuracy.

Statistical Methods

The study used Joinpoint analysis software (version 5.0.2 or 5.2.0) to assess temporal trends in cancer incidence rates. Joinpoint analysis was used to identify points of trend change (joinpoints), calculate the annual percentage change (APC) between joinpoints, and assess the significance of trends. Standard errors were used to weight annual data, calculate 95% confidence intervals (CIs), and evaluate significance through two-tailed t-tests.

Key Findings

Overall Trends

From 2004 to 2021, the incidence of distant-stage breast cancer among U.S. women increased significantly, with an APC of 1.16% (95% CI: 0.92, 1.42; p < .001). This trend was observed across all age groups, particularly among women aged 20-39 and those aged 75 and older.

Age Group Analysis

  • Women aged 20-39: The incidence of distant-stage breast cancer increased consistently throughout the study period, with an APC of 2.91% (95% CI: 2.43, 3.45; p < .001).
  • Women aged 40-74: The incidence increased significantly from 2004 to 2010 (APC, 2.10%; p = .002), showed no significant change from 2010 to 2018, and increased again from 2018 to 2021 (APC, 2.73%; p = .01).
  • Women aged 75 and older: The incidence of distant-stage breast cancer increased significantly throughout the study period, with an APC of 1.44% (95% CI: 1.01, 1.92; p < .001).

Race and Ethnicity Analysis

  • Asian women: The incidence of distant-stage breast cancer increased significantly, with an APC of 2.90% (95% CI: 2.38, 3.54; p < .001).
  • Black women: The incidence increased significantly, with an APC of 0.86% (95% CI: 0.31, 1.46; p = .008).
  • Hispanic women: The incidence increased significantly, with an APC of 1.56% (95% CI: 1.12, 2.08; p < .001).
  • Native American women: The incidence increased significantly from 2004 to 2019 (APC, 3.86%; p = .04), but declined in 2020 and 2021 due to the impact of the COVID-19 pandemic.
  • White women: The incidence increased significantly from 2004 to 2012 (APC, 1.68%; p = .01), but showed no significant trend from 2012 to 2021.

Impact of COVID-19

In 2020, the incidence of distant-stage breast cancer decreased across all age groups, particularly among women aged 75 and older. In 2021, the incidence rebounded, suggesting that some cases may have been undiagnosed in 2020.

Conclusion

This study found that the incidence of distant-stage breast cancer among U.S. women increased significantly from 2004 to 2021, particularly among women aged 20-39, 40-74, and 75 and older. The incidence also increased significantly among Asian, Black, Hispanic, and Native American women. The disruption of breast cancer screening and diagnosis during the COVID-19 pandemic had a particularly pronounced impact on older women and women from racial and ethnic minority groups.

Research Significance

This study is the first to incorporate SEER data from the COVID-19 pandemic period, revealing long-term trends in the increasing incidence of distant-stage breast cancer. This finding underscores the importance of early screening and diagnosis, particularly among younger women and women from racial and ethnic minority groups. The results call for improvements in breast cancer screening strategies to ensure that all women have access to high-quality medical care.

Research Highlights

  • Key Findings: The incidence of distant-stage breast cancer increased significantly across all age groups and multiple racial/ethnic groups.
  • Methodological Innovation: The use of Joinpoint software for trend analysis, incorporating data from the COVID-19 pandemic period for the first time.
  • Public Health Significance: The results highlight the urgency of improving breast cancer screening and diagnostic strategies, particularly for younger women and women from racial and ethnic minority groups.

Additional Valuable Information

The study also noted that the incidence of distant-stage breast cancer among Black women was 55% higher than among White women, which may contribute to the higher breast cancer mortality rates among Black women. Additionally, the COVID-19 pandemic had a greater impact on breast cancer diagnosis among older women and women from racial and ethnic minority groups, indicating disparities in access to healthcare resources for these populations.