ASPO Abstracts
Changes in racial/ethnic disparities and incidence rates of distant stage breast cancer by age, 1992-2015
Category: Cancer Health Disparities
Conference Year: 2020
Abstract Body:
Purpose of the study: Breast cancer (BC) incidence in US women under age 50 has increased in recent decades,
with the largest increase for distant stage in women <40 years old. However, it is unclear if this trend has persisted
and if it is consistent across racial/ethnic groups. Methods: We used five additional years of data from Surveillance
Epidemiology and End Results Program 13 (SEER) to update previously published age-specific distant stage BC
incidence trends from 1992-2015 by age group (25-84 years) and racial/ethnic groups (excluding American Indian
/Alaska Natives). We estimated annual percent change (APC) and average APC (AAPC) of incidence rate trends
using joinpoint software. We also used SEER Health Disparities software (HD*Calc) to calculate racial/ethnic
absolute (difference) and relative (ratio) disparity measures comparing racial/ethnic groups with the highest and
lowest incidence rates (range measures) and comparing Non-Hispanic (NH) white women to other racial/ethnic
groups (rate measures). Results: In all racial/ethnic groups, incidence rates for distant stage BC increased in
women aged 25-39 (NH White AAPC: 4.2% (95% CI: 3.5, 5.0), NH Black AAPC: 3.3% (95% CI: 2.1, 4.6), NH API
AAPC: 3.5% (95% CI: 1.2, 5.9), Hispanic AAPC: 2.5% (95% CI: 1.2, 3.9)); smaller but statistically significant
increases were also observed in women aged 40-54 across all racial/ethnic groups (range of 0.5% in NH White
and Hispanic women to 1.0% in NH API women), and in Non-Hispanic API women aged 55-69 (1.4%, 95% CI:
0.4, 2.3). In women aged 25-39, the range difference between racial/ethnic groups with the lowest and the highest
distant stage BC rates increased from 1.0 (95% CI: 0.1, 1.9) in 1992, to 2.3 (95% CI: 1.0-3.6) per 100,000 persons
in 2004. The trend over time for all other relative and absolute range disparity measures remained mostly
unchanged in all age groups, as did rate differences and ratios comparing NH white women to other racial/ethnic
groups. Conclusions: Distant stage BC incidence has increased steadily from 1992-2015 in young women of all
racial/ethnic backgrounds, and in NH API women for most age groups. Racial/ethnic disparities in distant stage BC
persist and remained relatively stable during this time interval.
Keywords: Breast cancer in the US; young women; distant stage; disparities