Ethnic differences in cancer mortality trends in the US, 1950-1992

Objective. To describe long-term mortality trends by ethnicity, sex, and age for selected cancers and to assess the effect of age-adjustment using different standard populations on rate ratios and rate differences comparing black to white cancer mortality. Design. Mortality rates for selected cancers were obtained from published reports of the Vital Statistics of the United States (1950-1992). All ethnic- and sex-specific cancer rates were directly age-adjusted to the total 1970 US standard population and to a subset of the 1970 US standard population 40 years and older. Results. Over a 42-year period, lung cancer mortality increased in all population subgroups. Colorectal cancer mortality declined in whites, but increased in blacks. Prostate cancer mortality increased slightly in white men, but dramatically increased in black men. Breast cancer mortality stabilized in white women, but increased markedly in black women. Uterine cancer mortality declined for both ethnicities, while ovarian cancer mortality rates increased for both ethnicities. As expected, the ratios of the age-adjusted cancer mortality rates comparing blacks to whites were the same regardless of the age structure used as the standard population. In contrast, the differences in the age-adjusted rates between blacks and whites were greater when the age-truncated standard population was used. Conclusions. There are unexplained ethnic differences in the long-term mortality trends of selected cancers. Of particular concern are the increasing death rates in black individuals from colorectal, prostate, breast, and ovarian cancers. Since almost all deaths from these cancers occur in persons over 40, age-adjustment using an age-truncated standard population that includes only those age groups at risk should be considered, particularly when the question to be addressed is one dealing with the impact of a characteristic, such as ethnicity or sex, on mortality risk.