Trends in Incidence of Invasive Lobular Carcinoma of the Breast by Race: Patterns by Age, Cancer Stage, and Socioeconomic Factors in the United States, 1992-2019

Purpose: There is scarce literature about the role of race/ethnicity and socioeconomic status on the incidence of invasive lobular carcinoma (ILC). We sought to assess trends in ILC incidence by race/ethnicity across age, cancer stage, and socioeconomic status subgroups in the United States from 1992 to 2019.

Methods: This population-based cross-sectional study included data from SEER12 registries. We used the NCI's Join point Regression Program to estimate longitudinal trends in age-adjusted breast cancer incidence rates from 1992 to 2019, reported as average annual percent change (AAPC) or annual percent change (APC). We evaluated incidence trends by a combination of race/ethnicity and stage, county-level poverty, county-level metro/nonmetro status, high school education, and age.

Results: From 1992 to 2019, ILC incidence rates increased across all race/ethnicity groups, with the greatest increase in non Hispanic Black (AAPC 2.6%), followed by Hispanic (AAPC 2.2%), and non Hispanic White women (AAPC 1.6%). The stronger increase in ILC incidence among Hispanic and non Hispanic Black women was predominantly seen among those living in low poverty or metropolitan areas and those older than 70. In recent years, from 2002 to 2019, the largest increase in ILC incidence was found in Hispanic women (APC 3.3%).

Conclusion: Although the incidence of ILC continues to be highest in non Hispanic White women, in recent years the largest increases are seen in non Hispanic Black women and Hispanic women. Further research is warranted to better understand these trends and appropriately target at-risk populations for screening.