Measures of racial/ethnic health disparities in cancer mortality rates and the influence of socioeconomic status.

OBJECTIVES: In the 1990s, U.S. cancer mortality rates declined due to reductions in tobacco use among men and beneficial cancer interventions, such as mammography and Pap smears. We examined the cancer rates by racial/ethnic group, socioeconomic status and time period to identify disparities underlying the overall mortality trend.

METHODS: We examined racial/ethnic disparities by measuring excess cancer burden [rate ratio (RR) and ratio differences (RD)] and trends in their cancer rates for nine cancer sites. The trend (T) is calculated as a ratio of the average annual cancer mortality rate for 1995-2000 relative to the rate for 1990-1994 for three levels of poverty (counties with <10% living below the poverty level, 10% - <20% and > or =20%) for the major racial/ethnic populations. We also compared the trend for each racial/ethnic SES group to the trend for lowest SES white group (TD).

RESULTS: Blacks have RR disparities relative to whites for each cancer site examined, except for female lung cancer, while the other minorities had RR disparities for cervical cancer (RR>1). There are increases in RR disparities from 1990-1994 to 1995-2000 (RD>0) for colorectal cancer, prostate cancer and breast cancer for each racial/ethnic minority. Whites and blacks had declining trends for every SES group (T<1) and positive high SES gradients (the highest SES group had the best trend and the lowest SES group had the worst trend) at each cancer site, except female lung cancer (T>1). In contrast, American Indians/Alaska natives, Hispanics and Asians/ Pacific Islanders had increasing trends for some of their cancer sites, and their trends did not have the SES gradients.

CONCLUSIONS: Increases in racial/ethnic disparities (RD>0) for colorectal, breast and prostate cancer were largest in the lowest SES groups. At some cancer sites, the highest SES group for minorities had worse trend results than the trends for the lowest SES white group (TD>0).