The prognostic significance of race and survival from breast cancer: a model for assessing the reliability of reported survival differences.

For more than 20 years, black women with breast cancer have been reported to have a lower survival rate than white women with breast cancer. Despite correcting for stage and socioeconomic status, some studies continue to report race-related excess mortality. A reliability scoring system was developed, based primarily on the precision of the staging system used, and the likelihood that the quality of treatment was comparable. Studies that compared the survival of blacks and whites treated for breast cancer from 1968 to 1988 were included in this study. Studies that demonstrated relatively large differences in the 5-year survival between blacks and whites were associated with low reliability scores. Studies that reported little or no difference in 5-year survival rates were associated with relatively high reliability scores. This model and the literature on which it is based suggest that the reported survival differences associated with race can be explained by differences in stage at presentation and by differences in the quality of care received. Efforts directed at early detection and improvements in the quality of care delivered are likely to reduce the excess breast cancer mortality experienced by black women.