Abstract
BACKGROUND: After new cancer data are released in April 2021, it is important to update the incidence trend in breast cancer from 2000 to 2018 and focus on ethnic disparities in the risk of developing breast cancer. METHODS: We identified 1129,564 women who were diagnosed with incident breast cancer at age ≥ 20 in 2000-2018 from 18 SEER (Surveillance, Epidemiology, and End Results) registries. We utilized the SEER*Stat software to calculate age-adjusted incidence rates. RESULTS: Overall age-adjusted incidence rate of breast cancer was the highest in non-Hispanic white (NHW) women (190.4 cases per 100,000 women), followed by NH-black (NHB) (178.4), Asian/Pacific-Islanders (API) (141.3), Hispanic (133.3) and American-Indians/Alaska-Native (AIAN) women (128.8). Annual percentage change (APC) from 2000 to 2018 showed that annual increase was statistically significant for API (APC: 1.0, 95% CI: 0.8-1.3), NHB (APC: 0.5, 0.2-0.7), AIAN (1.6, 1.1-2.2), and Hispanic women (0.4, 0.2-0.7), but annual percentage of incidence did not significantly decrease for NHW (-0.1, -0.4 to -0.1). Incidence rates of hormone-receptor positive breast cancer increased from 2000 to 2018 in all ethnic women, while incidence rates of hormone-receptor negative breast cancer decreased. NHW and NHB women had a significantly higher risk of having breast cancer than API women. In 2012-2018, the risks of having local stage and distant stage breast cancer for NHW (1.31, 1.29-1.33 and 1.19, 1.16-1.21) and NHB (1.09, 1.07-1.11 and 1.31, 1.28-1.35) women were significantly higher than that of API women. CONCLUSIONS: The incidence of hormone-receptor positive breast cancer increased in all ethnic women from 2000 to 2018 while the incidence of hormone-receptor negative breast cancer decreased. There were still substantial racial disparities in breast cancer incidences.