Background: Ethnic disparities in breast cancer diagnoses and disease-specific survival (DSS) rates in the United States are well known. However, few studies have assessed differences specifically between Asians American(s) and other ethnic groups, particularly among Asian American(s) subgroups, in women aged 18-39 years.
Methods: The Surveillance, Epidemiology, and End Results database was used to identify women aged 18-39 years diagnosed with breast cancer from 1973 to 2009. Incidence rates, clinicopathologic features, and survival among broad ethnic groups and among Asian subgroups.
Results: A total of 55,153 breast cancer women aged 18-39 years were identified: 63.6% non-Hispanic white (NHW), 14.9% black, 12.8% Hispanic-white (HW), and 8.7% Asian. The overall incidence rates were stable from 1992 to 2009. Asian patients had the least advanced disease at presentation and the lowest risk of death compared with the other groups. All the Asian subgroups except the Hawaiian/Pacific Islander subgroup had better DSS than NHW, black, and HW patients. Advanced tumour stage was associated with poorer DSS in all the ethnic groups. High tumour grade was associated with poorer DSS in the NHW, black, HW, and Chinese groups. Younger age at diagnosis was associated with poorer DSS in the NHW and black groups.
Conclusion: The presenting clinical and pathologic features of breast cancer differ by ethnicity in the United States, and these differences impact survival in women younger than 40 years.