Race/Ethnicity and Late Stage Breast Cancer

Institution: University of Southern California
Investigator(s): David Delgado, Ph.D., M.P.H. -
Award Cycle: 1995 (Cycle I) Grant #: 1KB-0152 Award: $123,127
Award Type: New Investigator Awards
Research Priorities
Detection, Prognosis and Treatment>Imaging, Biomarkers, and Molecular Pathology: improving detection and diagnosis

Initial Award Abstract (1995)
Over 20 million Hispanics live in the United States, and more than 50% of them live in California. Between 1974 and 1991, over 50,000 cases of breast cancer have been diagnosed in Los Angeles White and Hispanic women, making it an issue of extreme importance. Breast cancer accounts for the largest number of incident cases of cancer among all ethnic groups in Los Angeles. With the LA Hispanic population age distribution reflecting that of third world countries, the issue of age and its impact in early breast cancer detection for the Hispanic population is also important to examine. Incidence rates for racial/ethnic groups have been published, but fail to account for socioeconomic status. Incidence rates by stage-of-diagnosis, socioeconomic status, age, and race/ethnicity are not readily available.

The State of California's Breast Cancer Early Detection Program specifically targets women of lower socioeconomic status and minority racial/ethnic groups in order to improve breast cancer survival and reduce stage-at-diagnosis. In order to measure the progress and success of this program and other similar programs attempting to encourage earlier screening, appropriate baseline data will be needed. In particular, it will be important to be able to confidently examine changes in stage-of-diagnosis over time for subgroups of the population defined by race/ethnicity, age and socioeconomic status. One of the major contributions of this research will be to use various sophisticated statistical techniques (empirical Bayes and constrained empirical Bayes methodology) to provide reliable incidence rates calculated for these sub-populations. This type of methodology will help examine the incidence of late-stage breast cancer as it relates to socioeconomic status, race/ethnicity, and time period, after adjusting for age.

Finally, this methodology will help in studying the combination of all of the above variables in order to better understand the potential impact of early detection interventions. This study can provide a geographically-defined baseline of stage-specific incidence rates from which future calculations of late stage-of-diagnosis can be compared. We will examine our data for all of Los Angeles, dividing the County for analysis purpose into 86 Medical Service Study Areas (MSSAs) to be targeted for analysis. The results will enable policy makers and community service agencies to target the worst MSSAs with programs for the early detection of breast cancer. We will identify these MSSAs of extreme poverty and estimate baseline information about the incidence of late-stage diagnosis on a racial/ethnic and age-specific basis. Not only should our analysis help to focus future health education/outreach interventions, but will also offer a baseline from which to evaluate the effectiveness of these programs in the future.

Final Report (1996)
This study is an overview of the geographic distribution of late stage breast cancer in Los Angeles County for the periods 1976-1983 and 1984-1991, for White and Latina females, aged 20-49 and 50 and older, grouped into 87 Medical Service Study Areas (MSSAs), and for MSSAs of Low, Medium and High socioeconomic status (SES) based on levels of education and income. Each MSSA has a population of approximately 100,000 persons. Cancer incidence data were obtained for 21, 318 late-staged breast cancer patients diagnosed in L.A. County, gathered by the Cancer Surveillance Program of the University of Southern California, and linked to 1970/1980/1990 population data from the U.S. Census. We used a statistical technique called constrained empirical Bayes (CEB) to stabilize or "smooth" the Race/Ethnicity and Age-Specific incidence rates within the MSSA for each time period. Such smoothing is useful in instances where comparisons made based on relatively few numbers (of late-staged breast cancer) between MSSAs or time periods could be misleading (e.g., a change from 2 to 4 while very small is a change of 100% and would show as a doubling of a rate, in this case the incidence rate—in statistical terms, such rates are considered "unstable").

MSSAs with elevated rates for both White and Latino females were identified. Some associations were observed between lower SES (socio-economic status) and higher incidence rates, but overall, there was not strong consistent relationship. For example, during the period 1976-1991, for both White women aged 20 to 49, and for 50 and older, one low-SES MSSA in central Los Angeles (Huntington-Park/Slauson-Central) had the highest CEB rates for late-staged breast cancer. Older White women had approximately three times the risk of late staged cancer compared to younger White women across most MSSAs. During the same time period, the highest rate for younger Latina women (aged 20 to 49) was found in a high-SES MSSA covering what is called "west" LA (parts of Santa Monica & Westwood Village). The highest rate among Latino women aged 50 and older was found in an high-SES MSSA in the Southwest part of Los Angeles (the beach community of Redondo Beach south and the southwest portion of Torrance).

Overall in the county, irrespective of SES, among women aged 20 to 49, Latina’s incidence rates were about 15% lower that Whites (although in 9 MSSAs Latinas had slightly higher rates than Whites). Among women aged 50 and older, Latina rates were about 23% lower than Whites.

When comparing time periods 1976-83 and 1984-91 among White women, there were increases in late-stage incidence among low-SES MSSAs that, on average, were larger than increases observed in Middle and Upper SES MSSAs. Among Latinas, there were both increases and decreases in incidence which varied according to MSSA.

We have produced color maps outlining the distribution of these incidence rates for 87 MSSAs in LA county, focussing on Race/Ethnicity, Age distribution and Time Period. Our findings are suggestive and can be used to augment other information to help policy makers with issues of resource allocation, program planning and especially breast cancer program evaluation.