Tumor Biology Might Account for Racial Discrepancies
Black women living with breast cancer are more likely than white or Hispanic women with breast cancer to have larger tumors at the time of diagnosis and are more likely to have estrogen receptor-negative cancer, which is more difficult to treat, according to a study that will be published in the December issue of the journal Cancer, the New York Times reports (Bakalar, New York Times, 10/24).
Wendy Woodward, assistant professor of radiation oncology at the University of Texas MD Anderson Cancer Center, and colleagues enrolled 2,140 women in the Houston area in the study with the aim of determining tumor biology differences among racial groups.
About 24% of the black patients had later-stage breast cancer and tumors larger than five centimeters, compared with 16% of whites and 18% of Hispanics (Ackerman, Houston Chronicle, 10/24). All of the participants had advanced local breast cancer but did not show signs of metastasis, according to the study.
The average age of diagnosis was 49 for whites, 47 for Hispanics and 50 for blacks, and all participants had breast surgery before enrollment in the study. In addition, the women were followed for an average of 10 years.
All of the participants -- 1,456 of whom underwent chemotherapy after mastectomy and 684 before mastectomy -- were given the "same medical attention," according to the Times.
After statistically adjusting for differences in tumor size and ER-negative tumors at the time of diagnosis, the study found that 10-year survival rates among women who received chemotherapy before mastectomy was 50% for whites and 40% for blacks. Among women who received chemotherapy after surgery, 10-year survival rates were 52% for blacks and 62% for both whites and Hispanics.
The study also found that the survival rate among women who underwent chemotherapy after mastectomy and whose cancer had not spread to other organs was lower among blacks compared with whites and Hispanics. According to the Times, researchers did not suggest a potential mechanism to account for their findings, and the study did not control for chemotherapy doses and socioeconomic status.
The researchers said that blacks and Hispanics in Houston have similar demographics, but Hispanic participants had survival rates equal to or higher than the white participants (New York Times, 10/24).
"This doesn't mean every African-American woman is going to have a bad outcome," Woodward said, adding, "But is does suggest commonality that puts some at higher risk, and that should prompt us to develop better therapies for those women" (Houston Chronicle, 10/24).
According to the researchers, the study's findings indicate that the best way to further research the effects of tumor biology and race on treatment outcomes would be to conduct randomized trials of breast cancer treatments that take into account socioeconomic status and additional factors (New York Times, 10/24).
Peggy Porter, a researcher at Seattle-based Fred Hutchinson Cancer Research Center, said, "This study adds to the growing body of evidence that both tumor biology and access to care and other important socioeconomic factors are involved in lower survival rates seen among African-American women with breast cancer" (Houston Chronicle, 10/24).
According to the American Cancer Society, 211,000 women in the U.S. are diagnosed with breast cancer annually, and 40,000 die from it (Reuters, 10/23).