Context: In recent years a theory that cancer biology is different in blacks and whites has gained prominence in reaction to epidemiologic observations that blacks have poorer survival than whites, even when diagnosed with cancer of similar severity. Yet, few studies have evaluated whether lower-quality treatment and shorter overall life expectancy due to a greater burden of other illnesses may explain the survival discrepancy.
Objective: To estimate the magnitude of overall and cancer-specific survival differences between blacks and whites who receive comparable treatment for similar-stage cancer.
Data sources: We searched MEDLINE for English-language articles published from 1966 to January 2002 that reported on overall survival for black and white patients treated similarly for cancer.
Study selection: The abstracts or titles for 891 citations were independently examined by 2 authors. The full text was retrieved if the abstract mentioned both black and white patients, made some comment regarding either similarity of treatment received or presented an analysis based on the treatment received, and commented on survival. Studies were included if they included data for at least 10 black and 10 white patients; specified the cohort ascertainment method and what measures were undertaken to minimize loss to follow-up; summarized survival of both blacks and whites using actuarial measures; presented outcomes within stage, adjusted for stage, or based on cohorts with balanced stage distributions; and specified that blacks and whites in the study received similar treatment. We identified 89 unique cohorts in 54 articles that met our inclusion criteria.
Data extraction: Overall survival rates and hazard ratios (HRs) for death for blacks relative to whites were calculated. These were subsequently adjusted for rates of death due to causes other than the cancer under study to determine cancer-specific survival and cancer-specific HRs.
Data synthesis: Results represent 189 877 white and 32 004 black patients with 14 different cancers. Compared with whites, blacks had an overall excess risk of death (HR, 1.16; 95% confidence interval [CI], 1.12-1.20). After correction for deaths due to other causes, the cancer-specific HR was 1.07 (95% CI, 1.02-1.13). Of the 14 cancers, blacks were at a significantly higher risk of cancer-specific death only for cancer of the breast, uterus, or bladder.
Conclusions: Only modest cancer-specific survival differences are evident for blacks and whites treated comparably for similar-stage cancer. Therefore, differences in cancer biology between racial groups are unlikely to be responsible for a substantial portion of the survival discrepancy. Differences in treatment, stage at presentation, and mortality from other diseases should represent the primary targets of research and interventions designed to reduce disparities in cancer outcomes.