Medical researchers have taken a big step toward erasing what had appeared to be a puzzling racial difference in the outcomes of black women and white women with breast cancer. According to a report in tomorrow's issue of the journal Cancer, the two groups, diagnosed with the same type of breast tumor in the same stage of development, live equally long if they receive the same treatment.
Although breast cancer is more common among white women, statistics collected over the past several decades have shown that 75% of whites survive the disease 5 years after diagnosis compared to just 60% of blacks. While most experts agree that detecting breast cancer earlier in black women could help narrow that gap, some researchers have suggested that the difference lies in some unidentified racial factors.
The new finding is based on an analysis of two clinical trials in the National Surgical Adjuvant Breast and Bowel Project involving 108 black women and 916 whites. In one trial, women with a certain type of breast cancer—early-stage tumors with receptors for the hormone estrogen—received either surgery, the drug tamoxifen, or both. Combining data from the treatments, 93% of black patients and 92% of whites had survived 5 years after diagnosis. In the other trial, women with tumors that tend to grow more aggressively—those without estrogen receptors—received surgery with or without chemotherapy. A team led by James Dignam, a biostatistician at the University of Pittsburgh in Pittsburgh, found virtually no racial difference in mortality rates: 83% of black women and 85% of whites had survived to the 5-year mark.
Experts are impressed with the work. "The expectation is that there is black breast cancer and white breast cancer, and that they merit different treatments and different screening recommendations," says Otis Brawley, director of the Office of Special Populations at the National Cancer Institute. Instead, he says, the findings suggest that racial differences in breast cancer rates don't exist. Brawley says the study also calls into question 4-year-old National Institutes of Health rules mandating that all clinical trials look for racial differences in treatments.