Disparities between five-year cancer survival rates for white and black Americans--63 percent versus 52 percent, respectively--have scientists searching for answers. Large epidemiological studies have found that blacks continue to have poorer survival statistics than do whites even if they are diagnosed with cancer of similar severity, fueling speculation that cancer biology may be different for the two groups. But a report published today in the Journal of the American Medical Association adds further insight. The findings suggest that if patients receive equivalent treatment, the outcomes for blacks and whites can be strikingly similar.

Peter B. Bach of the Memorial Sloan-Kettering Cancer Center and colleagues examined data from 54 articles published over the last 36 years that compared both treatment and survival rates of black and white cancer victims. The results represented 189,877 white patients and 32,004 black patients who suffered from 14 different types of the disease. The researchers found that when patients received comparable care, the risk of death for black sufferers was 16 percent greater than that for whites. But once they considered deaths due to other causes, such as heart attacks, stroke or diabetes, this difference dropped to 7 percent. Specifically, the team determined that black patients had a significantly higher risk of death for only three types of cancer--breast cancer, uterine cancer and bladder cancer. Of particular note is the 70 percent increase in risk for blacks suffering from bladder cancer, a rarer type that accounted for 1 percent of all cancer deaths. According to the authors, "these findings suggest that if biological differences do exist, they are responsible for at most a very small fraction of all cancer deaths."

Though the scientists caution that their study did not include information on all types of cancer or ensure that every group studied received similar care, they conclude that differences in cancer biology are unlikely to be responsible for most of the survival discrepancy. Indeed, study co-author Colin Begg notes that "differences in treatment, stage of disease at presentation, and mortality from other diseases--not biologic or genetic differences--seem to explain most of the disparity."