Inter- and intra-ethnic differences for female breast carcinoma incidence in the continental United States and in the state of Hawaii.
BACKGROUND: Ethnic diversity is well-documented for female breast carcinoma incidence in the continental US but is not so well-established in the state of Hawaii. METHODS: Using the Surveillance, Epidemiology, and End Results (SEER) program, we analyzed n=323,607 in situ and invasive female breast cancer cases for major ethnic groups in the continental US and in Hawaii, diagnosed during the years 1992-2002. RESULTS: In the continental US, age-specific incidence rate patterns and prognostic factor profiles were good-risk for Asian or Pacific Islanders (API), intermediate for Whites, and poor-risk for Blacks. For example, early age-at-onset, high nuclear grade, aggressive histopathologic subtypes, and hormone receptor negative expression was associated with Black race in the continental US. In Hawaii, age-specific rate and prognostic profiles were more favorable for API than for White women, albeit not so striking as in the continental US. CONCLUSION: We observed inter- and intra-ethnic differences for female breast carcinoma in the continental US and in the state of Hawaii. While inter-racial disparities were expected, intra-racial differences were somewhat unexpected and possibly due to variations in racial subgroup mixing and/or cultural assimilation. For example, API women with breast carcinoma in the continental US included 96.03% Asians and 2.4% Pacific Islanders. In contrast, API women with breast carcinoma in Hawaii included 76.52% Asians and 23.46% Pacific Islanders. Moreover, APIs were more likely to be first-generation migrants in the continental US ( approximately 92%) than in Hawaii ( approximately 34%). Future studies should attempt to disaggregate racial data to separately characterize epidemiological patterns for individual ethnic groups.